USMLE Step 1 Qs (9)

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Quizzes Created: 14 | Total Attempts: 3,043

Questions: 50 | Attempts: 211 | Updated: Mar 20, 2023

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For those of you who love all things biology and living organisms especially anatomy and how stuff works in the human body then, USMLE Step 1 Qs (9 is for you. If you are prepared to test your knowledge try it out.

Questions and Answers

1.

Emma is a 64-year-old woman who has had heart disease for many years. While carrying chemicals down the stairs of the dry-cleaning shop where she worked, she suddenly lost control of her right leg and arm. She fell down the stairs and was able to stand up with some assistance from a coworker. When attempting to walk on her own, she had a very unsteady gait, with a tendency to fall to the right side. Her supervisor asked her if she was all right, and noticed that her speech was very slurred when she tried to answer. He called an ambulance to take her to the nearest hospital. The physician who was called to see Emma in the emergency room noted that her speech was slurred as if she were intoxicated, but the grammar and meaning were intact. Her face appeared symmetric, but when asked to protrude her tongue, it deviated toward the left. She was unable to tell if her right toe was moved up or down by the physician when she closed her eyes, and she couldn't feel the buzz of a tuning fork on her right arm and leg. In addition, her right arm and leg were markedly weak. The physician could find no other abnormalities on the remainder of Emma's general medical examination. Where in the nervous system could a lesion occur that causes arm and leg weakness, but spares the face?
- A.
  
  Right corticospinal tract in the cervical spinal cord
- B.
  
  Left inferior frontal lobe
- C.
  
  Left medullary pyramids
- D.
  
  Occipital lobe
- E.
  
  Both A and C are plausible sites
Correct Answer
E. Both A and C are plausible sites

Explanation
Emma has had a stroke resulting from occlusion of medial branches of the left vertebral artery, presumably secondary to atherosclerosis (i.e., cholesterol deposits within the artery, which eventually occlude it). The resulting syndrome is called the medial medullary syndrome, because the affected structures are located in the medial portion of the medulla. These structures include: the pyramids, the medial lemniscus, the medial longitudinal fasciculus, and the nucleus of the hypoglossal nerve and its outflow tract. Emma's symptoms result from damage to the aforementioned structures, and may have been caused by the same process (atherosclerosis) that resulted in her heart disease. The weakness of her right side was caused by damage to the medullary pyramid on the left side. Her face was spared because fibers supplying the face exited above the level of infarct. However, a lesion in the corticospinal tract of the cervical spinal cord above C5 could cause arm and leg weakness, and spare the face, because facial fibers exit in the rostral medulla. A lesion in the inferior portion of the precentral gyrus of the left frontal lobe would cause right-sided weakness, but would include the face, because this area is represented more inferiorly than are the extremities. Her unsteady gait was a result of the weakness of her right side, but may also have been the result of the loss of position and vibration sense on that side from damage to the medial lemniscus (as demonstrated by the inability to identify the position of her toe with her eyes closed, and the inability to feel the vibrations of a tuning fork). Without position sense, walking becomes unsteady because it is necessary to feel the position of one's feet on the floor during normal gait. Damage to both the medial lemniscus and pyramids at this level causes problems on the contralateral side because this lesion is located rostral to the level where both of these fiber bundles cross to the opposite side of the brain. Damage to the descending component of the medial longitudinal fasciculus could only affect head and neck reflexes, but not gait. Gait is also unaffected by pain inputs. Deviation of the tongue occurs because fibers from the hypoglossal nucleus innervate the genioglossus muscle on the ipsilateral side of the tongue. This muscle normally protrudes the tongue toward the contralateral side. Therefore, if one side is weak, the tongue will deviate toward the side ipsilateral to the lesion when protruded. A lesion in the precentral gyrus causes protrusion of the tongue toward the side that is contralateral to the lesion, because it is rostral to the crossing of fibers into the hypoglossal nucleus. Emma's speech was dysarthric (slurred) because her tongue was weak on the left side. The physician saw this during the exam when her tongue deviated to the left when protruded. Since the weakness of the tongue is purely a motor problem, rather than an effect that is manifested by a lesion to higher centers in the cortex (which mediate the structure and function of speech), the grammar, content, and meaning of Emma's speech remained intact, as would be expected with an aphasia or agnosia.

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2.

Emma is a 64-year-old woman who has had heart disease for many years. While carrying chemicals down the stairs of the dry-cleaning shop where she worked, she suddenly lost control of her right leg and arm. She fell down the stairs and was able to stand up with some assistance from a coworker. When attempting to walk on her own, she had a very unsteady gait, with a tendency to fall to the right side. Her supervisor asked her if she was all right, and noticed that her speech was very slurred when she tried to answer. He called an ambulance to take her to the nearest hospital. The physician who was called to see Emma in the emergency room noted that her speech was slurred as if she were intoxicated, but the grammar and meaning were intact. Her face appeared symmetric, but when asked to protrude her tongue, it deviated toward the left. She was unable to tell if her right toe was moved up or down by the physician when she closed her eyes, and she couldn't feel the buzz of a tuning fork on her right arm and leg. In addition, her right arm and leg were markedly weak. The physician could find no other abnormalities on the remainder of Emma's general medical examination. Other than the weakness on her right side, what type of deficit could cause Emma's gait problem, and where could a lesion causing this deficit occur?
- A.
  
  Proprioceptive, left medial lemniscus
- B.
  
  Sight, left eye
- C.
  
  Descending component of the medial longitudinal fasciculus
- D.
  
  Pain, left spinothalamic tract
- E.
  
  Proprioceptive, right medial lemniscus
Correct Answer
A. Proprioceptive, left medial lemniscus

Explanation
Emma has had a stroke resulting from occlusion of medial branches of the left vertebral artery, presumably secondary to atherosclerosis (i.e., cholesterol deposits within the artery, which eventually occlude it). The resulting syndrome is called the medial medullary syndrome, because the affected structures are located in the medial portion of the medulla. These structures include: the pyramids, the medial lemniscus, the medial longitudinal fasciculus, and the nucleus of the hypoglossal nerve and its outflow tract. Emma's symptoms result from damage to the aforementioned structures, and may have been caused by the same process (atherosclerosis) that resulted in her heart disease. The weakness of her right side was caused by damage to the medullary pyramid on the left side. Her face was spared because fibers supplying the face exited above the level of infarct. However, a lesion in the corticospinal tract of the cervical spinal cord above C5 could cause arm and leg weakness, and spare the face, because facial fibers exit in the rostral medulla. A lesion in the inferior portion of the precentral gyrus of the left frontal lobe would cause right-sided weakness, but would include the face, because this area is represented more inferiorly than are the extremities. Her unsteady gait was a result of the weakness of her right side, but may also have been the result of the loss of position and vibration sense on that side from damage to the medial lemniscus (as demonstrated by the inability to identify the position of her toe with her eyes closed, and the inability to feel the vibrations of a tuning fork). Without position sense, walking becomes unsteady because it is necessary to feel the position of one's feet on the floor during normal gait. Damage to both the medial lemniscus and pyramids at this level causes problems on the contralateral side because this lesion is located rostral to the level where both of these fiber bundles cross to the opposite side of the brain. Damage to the descending component of the medial longitudinal fasciculus could only affect head and neck reflexes, but not gait. Gait is also unaffected by pain inputs. Deviation of the tongue occurs because fibers from the hypoglossal nucleus innervate the genioglossus muscle on the ipsilateral side of the tongue. This muscle normally protrudes the tongue toward the contralateral side. Therefore, if one side is weak, the tongue will deviate toward the side ipsilateral to the lesion when protruded. A lesion in the precentral gyrus causes protrusion of the tongue toward the side that is contralateral to the lesion, because it is rostral to the crossing of fibers into the hypoglossal nucleus. Emma's speech was dysarthric (slurred) because her tongue was weak on the left side. The physician saw this during the exam when her tongue deviated to the left when protruded. Since the weakness of the tongue is purely a motor problem, rather than an effect that is manifested by a lesion to higher centers in the cortex (which mediate the structure and function of speech), the grammar, content, and meaning of Emma's speech remained intact, as would be expected with an aphasia or agnosia.

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3.

Emma is a 64-year-old woman who has had heart disease for many years. While carrying chemicals down the stairs of the dry-cleaning shop where she worked, she suddenly lost control of her right leg and arm. She fell down the stairs and was able to stand up with some assistance from a coworker. When attempting to walk on her own, she had a very unsteady gait, with a tendency to fall to the right side. Her supervisor asked her if she was all right, and noticed that her speech was very slurred when she tried to answer. He called an ambulance to take her to the nearest hospital. The physician who was called to see Emma in the emergency room noted that her speech was slurred as if she were intoxicated, but the grammar and meaning were intact. Her face appeared symmetric, but when asked to protrude her tongue, it deviated toward the left. She was unable to tell if her right toe was moved up or down by the physician when she closed her eyes, and she couldn't feel the buzz of a tuning fork on her right arm and leg. In addition, her right arm and leg were markedly weak. The physician could find no other abnormalities on the remainder of Emma's general medical examination. Deviation of the tongue to the left, away from the right hemiparesis, implies a lesion in which area of the nervous system
- A.
  
  Right hypoglossal nucleus
- B.
  
  Left hypoglossal nucleus
- C.
  
  Right inferior frontal lobe
- D.
  
  Left inferior frontal lobe
- E.
  
  Right cerebral peduncle
Correct Answer
B. Left hypoglossal nucleus

Explanation
Emma has had a stroke resulting from occlusion of medial branches of the left vertebral artery, presumably secondary to atherosclerosis (i.e., cholesterol deposits within the artery, which eventually occlude it). The resulting syndrome is called the medial medullary syndrome, because the affected structures are located in the medial portion of the medulla. These structures include: the pyramids, the medial lemniscus, the medial longitudinal fasciculus, and the nucleus of the hypoglossal nerve and its outflow tract. Emma's symptoms result from damage to the aforementioned structures, and may have been caused by the same process (atherosclerosis) that resulted in her heart disease. The weakness of her right side was caused by damage to the medullary pyramid on the left side. Her face was spared because fibers supplying the face exited above the level of infarct. However, a lesion in the corticospinal tract of the cervical spinal cord above C5 could cause arm and leg weakness, and spare the face, because facial fibers exit in the rostral medulla. A lesion in the inferior portion of the precentral gyrus of the left frontal lobe would cause right-sided weakness, but would include the face, because this area is represented more inferiorly than are the extremities. Her unsteady gait was a result of the weakness of her right side, but may also have been the result of the loss of position and vibration sense on that side from damage to the medial lemniscus (as demonstrated by the inability to identify the position of her toe with her eyes closed, and the inability to feel the vibrations of a tuning fork). Without position sense, walking becomes unsteady because it is necessary to feel the position of one's feet on the floor during normal gait. Damage to both the medial lemniscus and pyramids at this level causes problems on the contralateral side because this lesion is located rostral to the level where both of these fiber bundles cross to the opposite side of the brain. Damage to the descending component of the medial longitudinal fasciculus could only affect head and neck reflexes, but not gait. Gait is also unaffected by pain inputs. Deviation of the tongue occurs because fibers from the hypoglossal nucleus innervate the genioglossus muscle on the ipsilateral side of the tongue. This muscle normally protrudes the tongue toward the contralateral side. Therefore, if one side is weak, the tongue will deviate toward the side ipsilateral to the lesion when protruded. A lesion in the precentral gyrus causes protrusion of the tongue toward the side that is contralateral to the lesion, because it is rostral to the crossing of fibers into the hypoglossal nucleus. Emma's speech was dysarthric (slurred) because her tongue was weak on the left side. The physician saw this during the exam when her tongue deviated to the left when protruded. Since the weakness of the tongue is purely a motor problem, rather than an effect that is manifested by a lesion to higher centers in the cortex (which mediate the structure and function of speech), the grammar, content, and meaning of Emma's speech remained intact, as would be expected with an aphasia or agnosia

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4.

Emma is a 64-year-old woman who has had heart disease for many years. While carrying chemicals down the stairs of the dry-cleaning shop where she worked, she suddenly lost control of her right leg and arm. She fell down the stairs and was able to stand up with some assistance from a coworker. When attempting to walk on her own, she had a very unsteady gait, with a tendency to fall to the right side. Her supervisor asked her if she was all right, and noticed that her speech was very slurred when she tried to answer. He called an ambulance to take her to the nearest hospital. The physician who was called to see Emma in the emergency room noted that her speech was slurred as if she were intoxicated, but the grammar and meaning were intact. Her face appeared symmetric, but when asked to protrude her tongue, it deviated toward the left. She was unable to tell if her right toe was moved up or down by the physician when she closed her eyes, and she couldn't feel the buzz of a tuning fork on her right arm and leg. In addition, her right arm and leg were markedly weak. The physician could find no other abnormalities on the remainder of Emma's general medical examination. What type of speech problem does Emma have?
- A.
  
  Broca's aphasia
- B.
  
  Wernicke's aphasia
- C.
  
  Mixed aphasia
- D.
  
  Dysarthria
- E.
  
  Agnosia
Correct Answer
D. Dysarthria

Explanation
Emma has had a stroke resulting from occlusion of medial branches of the left vertebral artery, presumably secondary to atherosclerosis (i.e., cholesterol deposits within the artery, which eventually occlude it). The resulting syndrome is called the medial medullary syndrome, because the affected structures are located in the medial portion of the medulla. These structures include: the pyramids, the medial lemniscus, the medial longitudinal fasciculus, and the nucleus of the hypoglossal nerve and its outflow tract. Emma's symptoms result from damage to the aforementioned structures, and may have been caused by the same process (atherosclerosis) that resulted in her heart disease. The weakness of her right side was caused by damage to the medullary pyramid on the left side. Her face was spared because fibers supplying the face exited above the level of infarct. However, a lesion in the corticospinal tract of the cervical spinal cord above C5 could cause arm and leg weakness, and spare the face, because facial fibers exit in the rostral medulla. A lesion in the inferior portion of the precentral gyrus of the left frontal lobe would cause right-sided weakness, but would include the face, because this area is represented more inferiorly than are the extremities. Her unsteady gait was a result of the weakness of her right side, but may also have been the result of the loss of position and vibration sense on that side from damage to the medial lemniscus (as demonstrated by the inability to identify the position of her toe with her eyes closed, and the inability to feel the vibrations of a tuning fork). Without position sense, walking becomes unsteady because it is necessary to feel the position of one's feet on the floor during normal gait. Damage to both the medial lemniscus and pyramids at this level causes problems on the contralateral side because this lesion is located rostral to the level where both of these fiber bundles cross to the opposite side of the brain. Damage to the descending component of the medial longitudinal fasciculus could only affect head and neck reflexes, but not gait. Gait is also unaffected by pain inputs. Deviation of the tongue occurs because fibers from the hypoglossal nucleus innervate the genioglossus muscle on the ipsilateral side of the tongue. This muscle normally protrudes the tongue toward the contralateral side. Therefore, if one side is weak, the tongue will deviate toward the side ipsilateral to the lesion when protruded. A lesion in the precentral gyrus causes protrusion of the tongue toward the side that is contralateral to the lesion, because it is rostral to the crossing of fibers into the hypoglossal nucleus. Emma's speech was dysarthric (slurred) because her tongue was weak on the left side. The physician saw this during the exam when her tongue deviated to the left when protruded. Since the weakness of the tongue is purely a motor problem, rather than an effect that is manifested by a lesion to higher centers in the cortex (which mediate the structure and function of speech), the grammar, content, and meaning of Emma's speech remained intact, as would be expected with an aphasia or agnosia.

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5.

A second-year medical student was asked to see a nursing home patient as a requirement for a physical diagnosis course. The patient was a 79-year-old man who was apparently in a coma. The student wasn't certain of how to approach this case, so he asked the patient's wife, who was sitting at the bedside, why this patient was in a coma. The wife replied: "Oh, Paul isn't in a coma. But he did have a stroke." Slightly confused, the student leaned over and asked Paul to open his eyes. He opened his eyes immediately. However, when asked to lift his arm or speak, Paul did nothing. The student then asked Paul's wife if she was certain that his eye opening was not simply a coincidence, and that he really was in a coma, since he was unable to follow any commands. Paul's wife explained that he was unable to move or speak as a result of his stroke. However, she knew that he was awake, because he could communicate with her by blinking his eyes. The student appeared rather skeptical, so Paul's wife asked her husband to blink once for "yes" and twice for "no." She then asked him if he were at home and he blinked twice. When asked if he were in a nursing home, he blinked once. The student then asked him to move his eyes, and he was able to look in his direction. However, when the student asked him if he could move his arms or legs, he blinked twice. He also blinked twice when asked if he could smile. He did the same when asked if he could feel someone moving his arm. The student thanked Paul and his wife for their time, made notes of his findings, and returned to class. Where in the nervous system could a lesion occur that can cause paralysis of the extremities bilaterally, as well as the face, but not of the eyes?
- A.
  
  High cervical spinal cord bilaterally
- B.
  
  Bilateral thalamus
- C.
  
  Bilateral basal ganglia
- D.
  
  Bilateral pontine tegmentum
- E.
  
  Bilateral frontal lobe
Correct Answer
D. Bilateral pontine tegmentum

Explanation
This is an example of the locked-in syndrome, or pseudocoma, caused by an infarction of the pontine tegmentum. Because the tracts mediating movement of the limbs and face run through this region, the patient is unable to move the face, as well as both arms and legs. Consciousness and eye movements are preserved. The pontine tegmentum is mainly supplied by the basilar artery. Complete occlusion of this artery causes deficits on both sides since this artery supplies both sides of the pons. Basilar artery occlusion causes damage to the basilar pons, where the corticospinal and corticobulbar tracts run. These tracts contain motor fibers mediating movement of the limb and face, respectively. This results in complete paralysis to both sides of the body and the face. None of the tracts in the other choices mediate conscious movement. Sensory loss, including loss of proprioception (feeling the movement of a limb), also occurs as a result of damage to the medial lemniscus bilaterally. This tract contains fibers from the dorsal columns and also runs through the pontine tegmentum. Patients with the locked-in syndrome are often mistaken for comatose patients due to their inability to move or speak. If the lesion spares the reticular formation, an area mediating consciousness in the pons, the patient will remain alert.

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6.

A second-year medical student was asked to see a nursing home patient as a requirement for a physical diagnosis course. The patient was a 79-year-old man who was apparently in a coma. The student wasn't certain of how to approach this case, so he asked the patient's wife, who was sitting at the bedside, why this patient was in a coma. The wife replied: "Oh, Paul isn't in a coma. But he did have a stroke." Slightly confused, the student leaned over and asked Paul to open his eyes. He opened his eyes immediately. However, when asked to lift his arm or speak, Paul did nothing. The student then asked Paul's wife if she was certain that his eye opening was not simply a coincidence, and that he really was in a coma, since he was unable to follow any commands. Paul's wife explained that he was unable to move or speak as a result of his stroke. However, she knew that he was awake, because he could communicate with her by blinking his eyes. The student appeared rather skeptical, so Paul's wife asked her husband to blink once for "yes" and twice for "no." She then asked him if he were at home and he blinked twice. When asked if he were in a nursing home, he blinked once. The student then asked him to move his eyes, and he was able to look in his direction. However, when the student asked him if he could move his arms or legs, he blinked twice. He also blinked twice when asked if he could smile. He did the same when asked if he could feel someone moving his arm. The student thanked Paul and his wife for their time, made notes of his findings, and returned to class. An infarct in what vascular distribution could cause this lesion
- A.
  
  Anterior spinal artery
- B.
  
  Vertebral artery
- C.
  
  Basilar artery
- D.
  
  Middle cerebral artery
- E.
  
  Posterior cerebral artery
Correct Answer
C. Basilar artery

Explanation
This is an example of the locked-in syndrome, or pseudocoma, caused by an infarction of the pontine tegmentum. Because the tracts mediating movement of the limbs and face run through this region, the patient is unable to move the face, as well as both arms and legs. Consciousness and eye movements are preserved. The pontine tegmentum is mainly supplied by the basilar artery. Complete occlusion of this artery causes deficits on both sides since this artery supplies both sides of the pons. Basilar artery occlusion causes damage to the basilar pons, where the corticospinal and corticobulbar tracts run. These tracts contain motor fibers mediating movement of the limb and face, respectively. This results in complete paralysis to both sides of the body and the face. None of the tracts in the other choices mediate conscious movement. Sensory loss, including loss of proprioception (feeling the movement of a limb), also occurs as a result of damage to the medial lemniscus bilaterally. This tract contains fibers from the dorsal columns and also runs through the pontine tegmentum. Patients with the locked-in syndrome are often mistaken for comatose patients due to their inability to move or speak. If the lesion spares the reticular formation, an area mediating consciousness in the pons, the patient will remain alert.

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7.

A second-year medical student was asked to see a nursing home patient as a requirement for a physical diagnosis course. The patient was a 79-year-old man who was apparently in a coma. The student wasn't certain of how to approach this case, so he asked the patient's wife, who was sitting at the bedside, why this patient was in a coma. The wife replied: "Oh, Paul isn't in a coma. But he did have a stroke." Slightly confused, the student leaned over and asked Paul to open his eyes. He opened his eyes immediately. However, when asked to lift his arm or speak, Paul did nothing. The student then asked Paul's wife if she was certain that his eye opening was not simply a coincidence, and that he really was in a coma, since he was unable to follow any commands. Paul's wife explained that he was unable to move or speak as a result of his stroke. However, she knew that he was awake, because he could communicate with her by blinking his eyes. The student appeared rather skeptical, so Paul's wife asked her husband to blink once for "yes" and twice for "no." She then asked him if he were at home and he blinked twice. When asked if he were in a nursing home, he blinked once. The student then asked him to move his eyes, and he was able to look in his direction. However, when the student asked him if he could move his arms or legs, he blinked twice. He also blinked twice when asked if he could smile. He did the same when asked if he could feel someone moving his arm. The student thanked Paul and his wife for their time, made notes of his findings, and returned to class. Damage to which tracts caused Paul's inability to move his arms and legs?
- A.
  
  Corticospinal and corticobulbar tracts
- B.
  
  Spinothalamic tract
- C.
  
  Solitary tract
- D.
  
  Superior cerebellar peduncle
- E.
  
  Inferior cerebellar peduncle
Correct Answer
A. Corticospinal and corticobulbar tracts

Explanation
This is an example of the locked-in syndrome, or pseudocoma, caused by an infarction of the pontine tegmentum. Because the tracts mediating movement of the limbs and face run through this region, the patient is unable to move the face, as well as both arms and legs. Consciousness and eye movements are preserved. The pontine tegmentum is mainly supplied by the basilar artery. Complete occlusion of this artery causes deficits on both sides since this artery supplies both sides of the pons. Basilar artery occlusion causes damage to the basilar pons, where the corticospinal and corticobulbar tracts run. These tracts contain motor fibers mediating movement of the limb and face, respectively. This results in complete paralysis to both sides of the body and the face. None of the tracts in the other choices mediate conscious movement. Sensory loss, including loss of proprioception (feeling the movement of a limb), also occurs as a result of damage to the medial lemniscus bilaterally. This tract contains fibers from the dorsal columns and also runs through the pontine tegmentum. Patients with the locked-in syndrome are often mistaken for comatose patients due to their inability to move or speak. If the lesion spares the reticular formation, an area mediating consciousness in the pons, the patient will remain alert.

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8.

A second-year medical student was asked to see a nursing home patient as a requirement for a physical diagnosis course. The patient was a 79-year-old man who was apparently in a coma. The student wasn't certain of how to approach this case, so he asked the patient's wife, who was sitting at the bedside, why this patient was in a coma. The wife replied: "Oh, Paul isn't in a coma. But he did have a stroke." Slightly confused, the student leaned over and asked Paul to open his eyes. He opened his eyes immediately. However, when asked to lift his arm or speak, Paul did nothing. The student then asked Paul's wife if she was certain that his eye opening was not simply a coincidence, and that he really was in a coma, since he was unable to follow any commands. Paul's wife explained that he was unable to move or speak as a result of his stroke. However, she knew that he was awake, because he could communicate with her by blinking his eyes. The student appeared rather skeptical, so Paul's wife asked her husband to blink once for "yes" and twice for "no." She then asked him if he were at home and he blinked twice. When asked if he were in a nursing home, he blinked once. The student then asked him to move his eyes, and he was able to look in his direction. However, when the student asked him if he could move his arms or legs, he blinked twice. He also blinked twice when asked if he could smile. He did the same when asked if he could feel someone moving his arm. The student thanked Paul and his wife for their time, made notes of his findings, and returned to class. Damage to which tract caused Paul's lack of perception of someone moving his arm?
- A.
  
  Corticospinal and corticobulbar
- B.
  
  Middle cerebellar peduncle
- C.
  
  Spinothalamic tract
- D.
  
  Rubrospinal tract
- E.
  
  Medial lemniscus
Correct Answer
E. Medial lemniscus

Explanation
This is an example of the locked-in syndrome, or pseudocoma, caused by an infarction of the pontine tegmentum. Because the tracts mediating movement of the limbs and face run through this region, the patient is unable to move the face, as well as both arms and legs. Consciousness and eye movements are preserved. The pontine tegmentum is mainly supplied by the basilar artery. Complete occlusion of this artery causes deficits on both sides since this artery supplies both sides of the pons. Basilar artery occlusion causes damage to the basilar pons, where the corticospinal and corticobulbar tracts run. These tracts contain motor fibers mediating movement of the limb and face, respectively. This results in complete paralysis to both sides of the body and the face. None of the tracts in the other choices mediate conscious movement. Sensory loss, including loss of proprioception (feeling the movement of a limb), also occurs as a result of damage to the medial lemniscus bilaterally. This tract contains fibers from the dorsal columns and also runs through the pontine tegmentum. Patients with the locked-in syndrome are often mistaken for comatose patients due to their inability to move or speak. If the lesion spares the reticular formation, an area mediating consciousness in the pons, the patient will remain alert.

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9.

A second-year medical student was asked to see a nursing home patient as a requirement for a physical diagnosis course. The patient was a 79-year-old man who was apparently in a coma. The student wasn't certain of how to approach this case, so he asked the patient's wife, who was sitting at the bedside, why this patient was in a coma. The wife replied: "Oh, Paul isn't in a coma. But he did have a stroke." Slightly confused, the student leaned over and asked Paul to open his eyes. He opened his eyes immediately. However, when asked to lift his arm or speak, Paul did nothing. The student then asked Paul's wife if she was certain that his eye opening was not simply a coincidence, and that he really was in a coma, since he was unable to follow any commands. Paul's wife explained that he was unable to move or speak as a result of his stroke. However, she knew that he was awake, because he could communicate with her by blinking his eyes. The student appeared rather skeptical, so Paul's wife asked her husband to blink once for "yes" and twice for "no." She then asked him if he were at home and he blinked twice. When asked if he were in a nursing home, he blinked once. The student then asked him to move his eyes, and he was able to look in his direction. However, when the student asked him if he could move his arms or legs, he blinked twice. He also blinked twice when asked if he could smile. He did the same when asked if he could feel someone moving his arm. The student thanked Paul and his wife for their time, made notes of his findings, and returned to class. What area is spared to preserve consciousness?
- A.
  
  Deep frontal white matter
- B.
  
  Pontine reticular formation
- C.
  
  Temporal lobes
- D.
  
  Prefrontal cortex
- E.
  
  Occipital lobe
Correct Answer
B. Pontine reticular formation

Explanation
This is an example of the locked-in syndrome, or pseudocoma, caused by an infarction of the pontine tegmentum. Because the tracts mediating movement of the limbs and face run through this region, the patient is unable to move the face, as well as both arms and legs. Consciousness and eye movements are preserved. The pontine tegmentum is mainly supplied by the basilar artery. Complete occlusion of this artery causes deficits on both sides since this artery supplies both sides of the pons. Basilar artery occlusion causes damage to the basilar pons, where the corticospinal and corticobulbar tracts run. These tracts contain motor fibers mediating movement of the limb and face, respectively. This results in complete paralysis to both sides of the body and the face. None of the tracts in the other choices mediate conscious movement. Sensory loss, including loss of proprioception (feeling the movement of a limb), also occurs as a result of damage to the medial lemniscus bilaterally. This tract contains fibers from the dorsal columns and also runs through the pontine tegmentum. Patients with the locked-in syndrome are often mistaken for comatose patients due to their inability to move or speak. If the lesion spares the reticular formation, an area mediating consciousness in the pons, the patient will remain alert.

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10.

Norma is a 75-year-old woman who had a stroke several months ago, manifested by numbness on her right side, including her arm, face, trunk, and leg. The numbness had improved somewhat over time, but did not completely disappear. One day, she noticed that brushing her right arm against a door was very painful. Thinking that perhaps this was "in her mind," she tried touching the right arm with her left hand, and this, too, was painful. Fearful that she may be having another stroke, she went immediately to see her neurologist at her local hospital. Norma's neurologist examined her and found that sensation for a pin, temperature, and vibration were diminished on the entire right side of her body. The degree of sensory loss was unchanged from an examination several months before. However, she had a large amount of discomfort with any type of stimulus, accompanied by some emotional disturbance. The discomfort was far out of proportion to the degree of the stimulus (e.g., a light touch to her right arm would engender a scream similar to that elicited by a knife). The remainder of her examination was normal. The neurologist told Norma that he didn't think that she had had a new stroke, but would order a head CT to be sure that there was no tumor or bleeding. In addition, he told her that if the head CT showed nothing new, she could begin a new medication that would help with the pain. Which of the following is the most likely location of the old stroke? Norma is a 75-year-old woman who had a stroke several months ago, manifested by numbness on her right side, including her arm, face, trunk, and leg. The numbness had improved somewhat over time, but did not completely disappear. One day, she noticed that brushing her right arm against a door was very painful. Thinking that perhaps this was "in her mind," she tried touching the right arm with her left hand, and this, too, was painful. Fearful that she may be having another stroke, she went immediately to see her neurologist at her local hospital. Norma's neurologist examined her and found that sensation for a pin, temperature, and vibration were diminished on the entire right side of her body. The degree of sensory loss was unchanged from an examination several months before. However, she had a large amount of discomfort with any type of stimulus, accompanied by some emotional disturbance. The discomfort was far out of proportion to the degree of the stimulus (e.g., a light touch to her right arm would engender a scream similar to that elicited by a knife). The remainder of her examination was normal. The neurologist told Norma that he didn't think that she had had a new stroke, but would order a head CT to be sure that there was no tumor or bleeding. In addition, he told her that if the head CT showed nothing new, she could begin a new medication that would help with the pain. Which of the following is the most likely location of the old stroke?
- A.
  
  Right precentral gyrus
- B.
  
  Left precentral gyrus
- C.
  
  Right ventral thalamus
- D.
  
  Left ventral thalamus
- E.
  
  Left cerebral peduncle
Correct Answer
D. Left ventral thalamus

Explanation
Norma's head CT showed an old stroke in her left ventral thalamus and no new lesions. A stroke involving the ventral posterolateral nucleus of the thalamus, especially several months after the stroke can produce an entity called the Déjérine-Roussy syndrome, or thalamic pain syndrome. Although there is sensory loss on the contralateral side, there is pain or discomfort out of proportion to the stimulus on the affected side of the body. Emotional disturbance aggravates the response. Some patients describe the sensation as knifelike or hot. As the deficit (numbness) resolves, the pain may lessen. This syndrome may also occur in lesions of the parietal white matter, and is thought to occur as a result of an imbalance of afferent sensory impulses. Sensation of the limbs and trunk are projected through the ventral posterior lateral nucleus of the thalamus to the somatosensory cortex. Sensory information from the face is carried through the trigeminal system to the ventral posteromedial nucleus, from which it is projected to the somatosensory cortex. The spinothalamic tract is the only sensory pathway listed that mediates pain. The periaqueductal gray is one area of many that produces analgesia when stimulated in both animals and in humans. It is an area with a high density of opiate receptors and opioidergic neurons, and is thought to represent a key area in gating pain. Many neurotransmitters have been implicated as pain modulators, including the opiates and enkephalins, norepinephrine, serotonin, substance P, GABA, and acetylcholine. Most analgesic medications are designed to target a particular aspect of the pain pathway. In more recent years, the advent of a class of drugs called tricyclic antidepressants has added another dimension to medical pain treatment. The methylated forms of these medications are useful blockers of serotonin reuptake. Since serotonin is known to be a pain modulator, it is thought that blocking the reuptake of serotonin enhances its action and facilitates the action of intrinsic opiates to relieve pain. This is a common class of drugs used to treat chronic pain, since these medications are not addictive.

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11.

Norma is a 75-year-old woman who had a stroke several months ago, manifested by numbness on her right side, including her arm, face, trunk, and leg. The numbness had improved somewhat over time, but did not completely disappear. One day, she noticed that brushing her right arm against a door was very painful. Thinking that perhaps this was "in her mind," she tried touching the right arm with her left hand, and this, too, was painful. Fearful that she may be having another stroke, she went immediately to see her neurologist at her local hospital. Norma's neurologist examined her and found that sensation for a pin, temperature, and vibration were diminished on the entire right side of her body. The degree of sensory loss was unchanged from an examination several months before. However, she had a large amount of discomfort with any type of stimulus, accompanied by some emotional disturbance. The discomfort was far out of proportion to the degree of the stimulus (e.g., a light touch to her right arm would engender a scream similar to that elicited by a knife). The remainder of her examination was normal. The neurologist told Norma that he didn't think that she had had a new stroke, but would order a head CT to be sure that there was no tumor or bleeding. In addition, he told her that if the head CT showed nothing new, she could begin a new medication that would help with the pain. Which two nuclei mediating sensation of the arms, face, legs, and trunk may have sustained damage from the original stroke?
- A.
  
  Lateral and medial geniculate nuclei of the thalamus
- B.
  
  Ventral posterior lateral and ventral posterior medial nuclei of the thalamus
- C.
  
  Putamen and globus pallidus
- D.
  
  Caudate and putamen
- E.
  
  Anterior and lateral dorsal nuclei of the thalamus
Correct Answer
B. Ventral posterior lateral and ventral posterior medial nuclei of the thalamus

Explanation
Norma's head CT showed an old stroke in her left ventral thalamus and no new lesions. A stroke involving the ventral posterolateral nucleus of the thalamus, especially several months after the stroke can produce an entity called the Déjérine-Roussy syndrome, or thalamic pain syndrome. Although there is sensory loss on the contralateral side, there is pain or discomfort out of proportion to the stimulus on the affected side of the body. Emotional disturbance aggravates the response. Some patients describe the sensation as knifelike or hot. As the deficit (numbness) resolves, the pain may lessen. This syndrome may also occur in lesions of the parietal white matter, and is thought to occur as a result of an imbalance of afferent sensory impulses. Sensation of the limbs and trunk are projected through the ventral posterior lateral nucleus of the thalamus to the somatosensory cortex. Sensory information from the face is carried through the trigeminal system to the ventral posteromedial nucleus, from which it is projected to the somatosensory cortex. The spinothalamic tract is the only sensory pathway listed that mediates pain. The periaqueductal gray is one area of many that produces analgesia when stimulated in both animals and in humans. It is an area with a high density of opiate receptors and opioidergic neurons, and is thought to represent a key area in gating pain. Many neurotransmitters have been implicated as pain modulators, including the opiates and enkephalins, norepinephrine, serotonin, substance P, GABA, and acetylcholine. Most analgesic medications are designed to target a particular aspect of the pain pathway. In more recent years, the advent of a class of drugs called tricyclic antidepressants has added another dimension to medical pain treatment. The methylated forms of these medications are useful blockers of serotonin reuptake. Since serotonin is known to be a pain modulator, it is thought that blocking the reuptake of serotonin enhances its action and facilitates the action of intrinsic opiates to relieve pain. This is a common class of drugs used to treat chronic pain, since these medications are not addictive.

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12.

Norma is a 75-year-old woman who had a stroke several months ago, manifested by numbness on her right side, including her arm, face, trunk, and leg. The numbness had improved somewhat over time, but did not completely disappear. One day, she noticed that brushing her right arm against a door was very painful. Thinking that perhaps this was "in her mind," she tried touching the right arm with her left hand, and this, too, was painful. Fearful that she may be having another stroke, she went immediately to see her neurologist at her local hospital. Norma's neurologist examined her and found that sensation for a pin, temperature, and vibration were diminished on the entire right side of her body. The degree of sensory loss was unchanged from an examination several months before. However, she had a large amount of discomfort with any type of stimulus, accompanied by some emotional disturbance. The discomfort was far out of proportion to the degree of the stimulus (e.g., a light touch to her right arm would engender a scream similar to that elicited by a knife). The remainder of her examination was normal. The neurologist told Norma that he didn't think that she had had a new stroke, but would order a head CT to be sure that there was no tumor or bleeding. In addition, he told her that if the head CT showed nothing new, she could begin a new medication that would help with the pain. Which pathway mediating pain is the afferent input into the infarcted area?
- A.
  
  Fasciculus gracilis
- B.
  
  Fasciculus cuneatus
- C.
  
  Spinocerebellar tract
- D.
  
  Spinothalamic tract
- E.
  
  Corticospinal tract
Correct Answer
D. Spinothalamic tract

Explanation
Norma's head CT showed an old stroke in her left ventral thalamus and no new lesions. A stroke involving the ventral posterolateral nucleus of the thalamus, especially several months after the stroke can produce an entity called the Déjérine-Roussy syndrome, or thalamic pain syndrome. Although there is sensory loss on the contralateral side, there is pain or discomfort out of proportion to the stimulus on the affected side of the body. Emotional disturbance aggravates the response. Some patients describe the sensation as knifelike or hot. As the deficit (numbness) resolves, the pain may lessen. This syndrome may also occur in lesions of the parietal white matter, and is thought to occur as a result of an imbalance of afferent sensory impulses. Sensation of the limbs and trunk are projected through the ventral posterior lateral nucleus of the thalamus to the somatosensory cortex. Sensory information from the face is carried through the trigeminal system to the ventral posteromedial nucleus, from which it is projected to the somatosensory cortex. The spinothalamic tract is the only sensory pathway listed that mediates pain. The periaqueductal gray is one area of many that produces analgesia when stimulated in both animals and in humans. It is an area with a high density of opiate receptors and opioidergic neurons, and is thought to represent a key area in gating pain. Many neurotransmitters have been implicated as pain modulators, including the opiates and enkephalins, norepinephrine, serotonin, substance P, GABA, and acetylcholine. Most analgesic medications are designed to target a particular aspect of the pain pathway. In more recent years, the advent of a class of drugs called tricyclic antidepressants has added another dimension to medical pain treatment. The methylated forms of these medications are useful blockers of serotonin reuptake. Since serotonin is known to be a pain modulator, it is thought that blocking the reuptake of serotonin enhances its action and facilitates the action of intrinsic opiates to relieve pain. This is a common class of drugs used to treat chronic pain, since these medications are not addictive.

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13.

Norma is a 75-year-old woman who had a stroke several months ago, manifested by numbness on her right side, including her arm, face, trunk, and leg. The numbness had improved somewhat over time, but did not completely disappear. One day, she noticed that brushing her right arm against a door was very painful. Thinking that perhaps this was "in her mind," she tried touching the right arm with her left hand, and this, too, was painful. Fearful that she may be having another stroke, she went immediately to see her neurologist at her local hospital. Norma's neurologist examined her and found that sensation for a pin, temperature, and vibration were diminished on the entire right side of her body. The degree of sensory loss was unchanged from an examination several months before. However, she had a large amount of discomfort with any type of stimulus, accompanied by some emotional disturbance. The discomfort was far out of proportion to the degree of the stimulus (e.g., a light touch to her right arm would engender a scream similar to that elicited by a knife). The remainder of her examination was normal. The neurologist told Norma that he didn't think that she had had a new stroke, but would order a head CT to be sure that there was no tumor or bleeding. In addition, he told her that if the head CT showed nothing new, she could begin a new medication that would help with the pain. Surgical stimulation of various regions of the central nervous system (CNS) has been shown to alleviate pain. What is the location of one of these areas producing analgesia?
- A.
  
  Anterior nucleus of the thalamus
- B.
  
  Caudate nucleus
- C.
  
  Anterior horn of the spinal cord
- D.
  
  Globus pallidus
- E.
  
  Periaqueductal gray
Correct Answer
E. Periaqueductal gray

Explanation
Norma's head CT showed an old stroke in her left ventral thalamus and no new lesions. A stroke involving the ventral posterolateral nucleus of the thalamus, especially several months after the stroke can produce an entity called the Déjérine-Roussy syndrome, or thalamic pain syndrome. Although there is sensory loss on the contralateral side, there is pain or discomfort out of proportion to the stimulus on the affected side of the body. Emotional disturbance aggravates the response. Some patients describe the sensation as knifelike or hot. As the deficit (numbness) resolves, the pain may lessen. This syndrome may also occur in lesions of the parietal white matter, and is thought to occur as a result of an imbalance of afferent sensory impulses. Sensation of the limbs and trunk are projected through the ventral posterior lateral nucleus of the thalamus to the somatosensory cortex. Sensory information from the face is carried through the trigeminal system to the ventral posteromedial nucleus, from which it is projected to the somatosensory cortex. The spinothalamic tract is the only sensory pathway listed that mediates pain. The periaqueductal gray is one area of many that produces analgesia when stimulated in both animals and in humans. It is an area with a high density of opiate receptors and opioidergic neurons, and is thought to represent a key area in gating pain. Many neurotransmitters have been implicated as pain modulators, including the opiates and enkephalins, norepinephrine, serotonin, substance P, GABA, and acetylcholine. Most analgesic medications are designed to target a particular aspect of the pain pathway. In more recent years, the advent of a class of drugs called tricyclic antidepressants has added another dimension to medical pain treatment. The methylated forms of these medications are useful blockers of serotonin reuptake. Since serotonin is known to be a pain modulator, it is thought that blocking the reuptake of serotonin enhances its action and facilitates the action of intrinsic opiates to relieve pain. This is a common class of drugs used to treat chronic pain, since these medications are not addictive.

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14.

Norma is a 75-year-old woman who had a stroke several months ago, manifested by numbness on her right side, including her arm, face, trunk, and leg. The numbness had improved somewhat over time, but did not completely disappear. One day, she noticed that brushing her right arm against a door was very painful. Thinking that perhaps this was "in her mind," she tried touching the right arm with her left hand, and this, too, was painful. Fearful that she may be having another stroke, she went immediately to see her neurologist at her local hospital. Norma's neurologist examined her and found that sensation for a pin, temperature, and vibration were diminished on the entire right side of her body. The degree of sensory loss was unchanged from an examination several months before. However, she had a large amount of discomfort with any type of stimulus, accompanied by some emotional disturbance. The discomfort was far out of proportion to the degree of the stimulus (e.g., a light touch to her right arm would engender a scream similar to that elicited by a knife). The remainder of her examination was normal. The neurologist told Norma that he didn't think that she had had a new stroke, but would order a head CT to be sure that there was no tumor or bleeding. In addition, he told her that if the head CT showed nothing new, she could begin a new medication that would help with the pain. Neurotransmitters implicated in pain modulation, which may be the targets of pain-alleviating drugs, include which of the following
- A.
  
  Aspartate
- B.
  
  Glutamate
- C.
  
  Epinephrine
- D.
  
  Dopamine and norepinephrine
- E.
  
  Opiates and serotonin
Correct Answer
E. Opiates and serotonin

Explanation
Norma's head CT showed an old stroke in her left ventral thalamus and no new lesions. A stroke involving the ventral posterolateral nucleus of the thalamus, especially several months after the stroke can produce an entity called the Déjérine-Roussy syndrome, or thalamic pain syndrome. Although there is sensory loss on the contralateral side, there is pain or discomfort out of proportion to the stimulus on the affected side of the body. Emotional disturbance aggravates the response. Some patients describe the sensation as knifelike or hot. As the deficit (numbness) resolves, the pain may lessen. This syndrome may also occur in lesions of the parietal white matter, and is thought to occur as a result of an imbalance of afferent sensory impulses. Sensation of the limbs and trunk are projected through the ventral posterior lateral nucleus of the thalamus to the somatosensory cortex. Sensory information from the face is carried through the trigeminal system to the ventral posteromedial nucleus, from which it is projected to the somatosensory cortex. The spinothalamic tract is the only sensory pathway listed that mediates pain. The periaqueductal gray is one area of many that produces analgesia when stimulated in both animals and in humans. It is an area with a high density of opiate receptors and opioidergic neurons, and is thought to represent a key area in gating pain. Many neurotransmitters have been implicated as pain modulators, including the opiates and enkephalins, norepinephrine, serotonin, substance P, GABA, and acetylcholine. Most analgesic medications are designed to target a particular aspect of the pain pathway. In more recent years, the advent of a class of drugs called tricyclic antidepressants has added another dimension to medical pain treatment. The methylated forms of these medications are useful blockers of serotonin reuptake. Since serotonin is known to be a pain modulator, it is thought that blocking the reuptake of serotonin enhances its action and facilitates the action of intrinsic opiates to relieve pain. This is a common class of drugs used to treat chronic pain, since these medications are not addictive.

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15.

Louise is an 86-year-old woman who has had difficulty with high blood pressure, high cholesterol, diabetes, strokes, and blood clots in her legs for many years. One day, her grandson arrived at her apartment in a senior citizen center for his weekly visit, only to find her lying unconscious on the floor. He immediately called an ambulance to bring her to the nearest emergency room. The paramedics in the ambulance gave Louise some medications, including glucose, but she did not awaken. She was brought to the nearest emergency room, where a physician was called to evaluate her. She was breathing on her own and had a pulse, but could not be aroused to any stimulus. Her arms and legs were stiff, and would not move in response to a painful stimulus. Her eyes moved in response to moving her head. Finally, in response to a very loud shout and pinch on the arm, she briefly opened her eyes; however, she immediately shut them again. Further attempts to arouse Louise were unsuccessful. She was taken for a CT scan of her head, and then brought to an intensive care unit. An acute stroke in which portion of the CNS could cause this picture?
- A.
  
  Right frontal lobe
- B.
  
  Left frontal lobe
- C.
  
  Right temporal lobe
- D.
  
  Pons and midbrain
- E.
  
  Right occipital lobe
Correct Answer
D. Pons and midbrain

Explanation
The CT scan of Louise's brain revealed a large, acute stroke of her upper pons and midbrain. Strokes of these areas often result from occlusion of the basilar artery and can produce coma, or a variant of hypersomnia called akinetic mutism or coma vigil. An EEG of a patient like this shows a pattern associated with slow-wave sleep, but eye movements are preserved. It is likely that the corticospinal tracts within the pons were damaged during this very large stroke, causing the increased tone from lack of inhibition, as well as the lack of movement in Louise's arms and legs. Infarctions of perforators of the basilar artery, supplying the reticular formation of the pons may cause coma. These perforators also supply the corticospinal tracts, causing the increased tone and weakness of Louise's legs, so a large stroke may involve both functions. Coma occurs because there is damage to the brainstem tegmentum, which is a major component of the ascending reticular activating system. Although it is not known exactly which area is precisely responsible for consciousness, lesions of this region, as well as projections from the medial regions of the midbrain reticular formation can produce coma. The two main monoaminergic systems of the reticular formation are the noradrenergic and serotonergic systems, originating in the locus ceruleus and raphe nuclei, respectively. The mesolimbic, mesostriatal, and mesocortical dopaminergic systems are located within the ventrorostral aspect of the brainstem, but not within the reticular formation.

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16.

Louise is an 86-year-old woman who has had difficulty with high blood pressure, high cholesterol, diabetes, strokes, and blood clots in her legs for many years. One day, her grandson arrived at her apartment in a senior citizen center for his weekly visit, only to find her lying unconscious on the floor. He immediately called an ambulance to bring her to the nearest emergency room. The paramedics in the ambulance gave Louise some medications, including glucose, but she did not awaken. She was brought to the nearest emergency room, where a physician was called to evaluate her. She was breathing on her own and had a pulse, but could not be aroused to any stimulus. Her arms and legs were stiff, and would not move in response to a painful stimulus. Her eyes moved in response to moving her head. Finally, in response to a very loud shout and pinch on the arm, she briefly opened her eyes; however, she immediately shut them again. Further attempts to arouse Louise were unsuccessful. She was taken for a CT scan of her head, and then brought to an intensive care unit. Which of the following is the most likely cause of the stiffness in Louise's arms and legs?
- A.
  
  Infarction of the corticospinal tracts bilaterally in the pons
- B.
  
  Damage to the basal ganglia
- C.
  
  Infarction of the precentral gyrus
- D.
  
  Infarction of the internal capsules bilaterally
- E.
  
  Thalamic infarction
Correct Answer
A. Infarction of the corticospinal tracts bilaterally in the pons

Explanation
The CT scan of Louise's brain revealed a large, acute stroke of her upper pons and midbrain. Strokes of these areas often result from occlusion of the basilar artery and can produce coma, or a variant of hypersomnia called akinetic mutism or coma vigil. An EEG of a patient like this shows a pattern associated with slow-wave sleep, but eye movements are preserved. It is likely that the corticospinal tracts within the pons were damaged during this very large stroke, causing the increased tone from lack of inhibition, as well as the lack of movement in Louise's arms and legs. Infarctions of perforators of the basilar artery, supplying the reticular formation of the pons may cause coma. These perforators also supply the corticospinal tracts, causing the increased tone and weakness of Louise's legs, so a large stroke may involve both functions. Coma occurs because there is damage to the brainstem tegmentum, which is a major component of the ascending reticular activating system. Although it is not known exactly which area is precisely responsible for consciousness, lesions of this region, as well as projections from the medial regions of the midbrain reticular formation can produce coma. The two main monoaminergic systems of the reticular formation are the noradrenergic and serotonergic systems, originating in the locus ceruleus and raphe nuclei, respectively. The mesolimbic, mesostriatal, and mesocortical dopaminergic systems are located within the ventrorostral aspect of the brainstem, but not within the reticular formation.

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17.

Louise is an 86-year-old woman who has had difficulty with high blood pressure, high cholesterol, diabetes, strokes, and blood clots in her legs for many years. One day, her grandson arrived at her apartment in a senior citizen center for his weekly visit, only to find her lying unconscious on the floor. He immediately called an ambulance to bring her to the nearest emergency room. The paramedics in the ambulance gave Louise some medications, including glucose, but she did not awaken. She was brought to the nearest emergency room, where a physician was called to evaluate her. She was breathing on her own and had a pulse, but could not be aroused to any stimulus. Her arms and legs were stiff, and would not move in response to a painful stimulus. Her eyes moved in response to moving her head. Finally, in response to a very loud shout and pinch on the arm, she briefly opened her eyes; however, she immediately shut them again. Further attempts to arouse Louise were unsuccessful. She was taken for a CT scan of her head, and then brought to an intensive care unit. Infarction of which artery may cause this picture
- A.
  
  Anterior cerebral artery
- B.
  
  Middle cerebral artery
- C.
  
  Anterior choroidal artery
- D.
  
  Basilar artery
- E.
  
  Lenticulostriate branches of the middle cerebral artery
Correct Answer
D. Basilar artery

Explanation
The CT scan of Louise's brain revealed a large, acute stroke of her upper pons and midbrain. Strokes of these areas often result from occlusion of the basilar artery and can produce coma, or a variant of hypersomnia called akinetic mutism or coma vigil. An EEG of a patient like this shows a pattern associated with slow-wave sleep, but eye movements are preserved. It is likely that the corticospinal tracts within the pons were damaged during this very large stroke, causing the increased tone from lack of inhibition, as well as the lack of movement in Louise's arms and legs. Infarctions of perforators of the basilar artery, supplying the reticular formation of the pons may cause coma. These perforators also supply the corticospinal tracts, causing the increased tone and weakness of Louise's legs, so a large stroke may involve both functions. Coma occurs because there is damage to the brainstem tegmentum, which is a major component of the ascending reticular activating system. Although it is not known exactly which area is precisely responsible for consciousness, lesions of this region, as well as projections from the medial regions of the midbrain reticular formation can produce coma. The two main monoaminergic systems of the reticular formation are the noradrenergic and serotonergic systems, originating in the locus ceruleus and raphe nuclei, respectively. The mesolimbic, mesostriatal, and mesocortical dopaminergic systems are located within the ventrorostral aspect of the brainstem, but not within the reticular formation.

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18.

Louise is an 86-year-old woman who has had difficulty with high blood pressure, high cholesterol, diabetes, strokes, and blood clots in her legs for many years. One day, her grandson arrived at her apartment in a senior citizen center for his weekly visit, only to find her lying unconscious on the floor. He immediately called an ambulance to bring her to the nearest emergency room. The paramedics in the ambulance gave Louise some medications, including glucose, but she did not awaken. She was brought to the nearest emergency room, where a physician was called to evaluate her. She was breathing on her own and had a pulse, but could not be aroused to any stimulus. Her arms and legs were stiff, and would not move in response to a painful stimulus. Her eyes moved in response to moving her head. Finally, in response to a very loud shout and pinch on the arm, she briefly opened her eyes; however, she immediately shut them again. Further attempts to arouse Louise were unsuccessful. She was taken for a CT scan of her head, and then brought to an intensive care unit. If the stroke occurred in the brainstem, which of the following regions is most likely affected
- A.
  
  Facial nerve nucleus
- B.
  
  Trochlear nerve nucleus
- C.
  
  Reticular formation
- D.
  
  Trigeminal system
- E.
  
  Medial longitudinal fasciculus
Correct Answer
C. Reticular formation

Explanation
The CT scan of Louise's brain revealed a large, acute stroke of her upper pons and midbrain. Strokes of these areas often result from occlusion of the basilar artery and can produce coma, or a variant of hypersomnia called akinetic mutism or coma vigil. An EEG of a patient like this shows a pattern associated with slow-wave sleep, but eye movements are preserved. It is likely that the corticospinal tracts within the pons were damaged during this very large stroke, causing the increased tone from lack of inhibition, as well as the lack of movement in Louise's arms and legs. Infarctions of perforators of the basilar artery, supplying the reticular formation of the pons may cause coma. These perforators also supply the corticospinal tracts, causing the increased tone and weakness of Louise's legs, so a large stroke may involve both functions. Coma occurs because there is damage to the brainstem tegmentum, which is a major component of the ascending reticular activating system. Although it is not known exactly which area is precisely responsible for consciousness, lesions of this region, as well as projections from the medial regions of the midbrain reticular formation can produce coma. The two main monoaminergic systems of the reticular formation are the noradrenergic and serotonergic systems, originating in the locus ceruleus and raphe nuclei, respectively. The mesolimbic, mesostriatal, and mesocortical dopaminergic systems are located within the ventrorostral aspect of the brainstem, but not within the reticular formation.

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19.

Louise is an 86-year-old woman who has had difficulty with high blood pressure, high cholesterol, diabetes, strokes, and blood clots in her legs for many years. One day, her grandson arrived at her apartment in a senior citizen center for his weekly visit, only to find her lying unconscious on the floor. He immediately called an ambulance to bring her to the nearest emergency room. The paramedics in the ambulance gave Louise some medications, including glucose, but she did not awaken. She was brought to the nearest emergency room, where a physician was called to evaluate her. She was breathing on her own and had a pulse, but could not be aroused to any stimulus. Her arms and legs were stiff, and would not move in response to a painful stimulus. Her eyes moved in response to moving her head. Finally, in response to a very loud shout and pinch on the arm, she briefly opened her eyes; however, she immediately shut them again. Further attempts to arouse Louise were unsuccessful. She was taken for a CT scan of her head, and then brought to an intensive care unit. Which of the following are the main monoaminergic systems of the region infarcted?
- A.
  
  Dopamine
- B.
  
  Norepinephrine
- C.
  
  Serotonin
- D.
  
  GABA
- E.
  
  Norepinephrine and serotonin
Correct Answer
E. Norepinephrine and serotonin

Explanation
The CT scan of Louise's brain revealed a large, acute stroke of her upper pons and midbrain. Strokes of these areas often result from occlusion of the basilar artery and can produce coma, or a variant of hypersomnia called akinetic mutism or coma vigil. An EEG of a patient like this shows a pattern associated with slow-wave sleep, but eye movements are preserved. It is likely that the corticospinal tracts within the pons were damaged during this very large stroke, causing the increased tone from lack of inhibition, as well as the lack of movement in Louise's arms and legs. Infarctions of perforators of the basilar artery, supplying the reticular formation of the pons may cause coma. These perforators also supply the corticospinal tracts, causing the increased tone and weakness of Louise's legs, so a large stroke may involve both functions. Coma occurs because there is damage to the brainstem tegmentum, which is a major component of the ascending reticular activating system. Although it is not known exactly which area is precisely responsible for consciousness, lesions of this region, as well as projections from the medial regions of the midbrain reticular formation can produce coma. The two main monoaminergic systems of the reticular formation are the noradrenergic and serotonergic systems, originating in the locus ceruleus and raphe nuclei, respectively. The mesolimbic, mesostriatal, and mesocortical dopaminergic systems are located within the ventrorostral aspect of the brainstem, but not within the reticular formation.

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20.

A 67-year-old man suffers an infarct of the geniculothalamic branch of the posterior cerebral artery. In particular, there is involvement of nuclei of the posterior thalamus. Which of the following is the most likely effect of such an infarct
- A.
  
  Emotional volatility in response to an innocuous statement
- B.
  
  Short-term memory loss that occurs about 1 week following the infarct
- C.
  
  Long-term memory loss that occurs about 1 month following the infarct
- D.
  
  Severe pain triggered by cutaneous stimuli applied to the patient
- E.
  
  Spastic paralysis of the contralateral limbs
Correct Answer
D. Severe pain triggered by cutaneous stimuli applied to the patient

Explanation
The infarct caused damage to posterior thalamic nuclei. When these structures are damaged, a disorder referred to as thalamic pain can ensue. In this condition, light cutaneous stimulation is sufficient to produce severe pain. The projections from nuclei situated in this region project principally to the parietal and occipital lobes and play a role in the regulation of pain (although the precise mechanisms remain unknown). The other processes offered as alternate choices have not been shown to be related to functions of the posterior thalamus

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21.

A 67-year-old man suffers an infarct of the geniculothalamic branch of the posterior cerebral artery. In particular, there is involvement of nuclei of the posterior thalamus. The neurons affected by this infarction project primarily to which of the following?
- A.
  
  Hypothalamus and midbrain
- B.
  
  Parietal and occipital cortices
- C.
  
  Precentral and postcentral gyri
- D.
  
  Basal ganglia and premotor cortex
- E.
  
  Prefrontal cortex and medial aspect of the frontal lobe
Correct Answer
B. Parietal and occipital cortices

Explanation
The infarct caused damage to posterior thalamic nuclei. When these structures are damaged, a disorder referred to as thalamic pain can ensue. In this condition, light cutaneous stimulation is sufficient to produce severe pain. The projections from nuclei situated in this region project principally to the parietal and occipital lobes and play a role in the regulation of pain (although the precise mechanisms remain unknown). The other processes offered as alternate choices have not been shown to be related to functions of the posterior thalamus.

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22.

A 52-year-old woman has an infarct involving a branch of the posterior communicating artery, causing damage to the ventral anterior (VA), ventrolateral (VL), dorsomedial, and anterior thalamic nuclei. Which of the following is the most likely clinical manifestations of this infarct
- A.
  
  Hemiparesis and neuropsychological impairment
- B.
  
  Loss of sleep and apnea
- C.
  
  Loss of appetite and thermoregulation
- D.
  
  Total blindness of the contralateral eye
- E.
  
  Marked endocrine dysfunction
Correct Answer
A. Hemiparesis and neuropsychological impairment

Explanation
Damage to the VA, VL, dorsomedial, and anterior thalamic nuclei would most likely result in motor impairment such as a hemiparesis (because of the connections of these nuclei with the motor and premotor cortices). Damage to the dorsomedial nucleus could also be linked with neuropsychological impairment, because of its connections with the prefrontal cortex and adjoining regions of the frontal lobe. The other processes mentioned in the question have not been shown to be related to these groups of nuclei. As noted earlier, the VA nucleus is associated with motor functions, not only in its projections to motor regions of the cerebral cortex—the premotor and prefrontal cortices—but also in the inputs that it receives from structures associated with motor functions such as the globus pallidus and substantia nigra.

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23.

A 52-year-old woman has an infarct involving a branch of the posterior communicating artery, causing damage to the ventral anterior (VA), ventrolateral (VL), dorsomedial, and anterior thalamic nuclei. The VA nucleus receives inputs primarily from structures associated with which of the following?
- A.
  
  Somatosensory functions
- B.
  
  Motor functions
- C.
  
  Autonomic functions
- D.
  
  Auditory and taste functions
- E.
  
  The regulation of sleep
Correct Answer
B. Motor functions

Explanation
Damage to the VA, VL, dorsomedial, and anterior thalamic nuclei would most likely result in motor impairment such as a hemiparesis (because of the connections of these nuclei with the motor and premotor cortices). Damage to the dorsomedial nucleus could also be linked with neuropsychological impairment, because of its connections with the prefrontal cortex and adjoining regions of the frontal lobe. The other processes mentioned in the question have not been shown to be related to these groups of nuclei. As noted earlier, the VA nucleus is associated with motor functions, not only in its projections to motor regions of the cerebral cortex—the premotor and prefrontal cortices—but also in the inputs that it receives from structures associated with motor functions such as the globus pallidus and substantia nigra.

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24.

A 52-year-old woman has an infarct involving a branch of the posterior communicating artery, causing damage to the ventral anterior (VA), ventrolateral (VL), dorsomedial, and anterior thalamic nuclei. The primary outputs of the VA nucleus include which of the following?
- A.
  
  Prefrontal and premotor cortices
- B.
  
  Precentral and postcentral gyri
- C.
  
  Posterior parietal lobe
- D.
  
  Middle temporal gyrus
- E.
  
  Wernicke's area
Correct Answer
A. Prefrontal and premotor cortices

Explanation
Damage to the VA, VL, dorsomedial, and anterior thalamic nuclei would most likely result in motor impairment such as a hemiparesis (because of the connections of these nuclei with the motor and premotor cortices). Damage to the dorsomedial nucleus could also be linked with neuropsychological impairment, because of its connections with the prefrontal cortex and adjoining regions of the frontal lobe. The other processes mentioned in the question have not been shown to be related to these groups of nuclei. As noted earlier, the VA nucleus is associated with motor functions, not only in its projections to motor regions of the cerebral cortex—the premotor and prefrontal cortices—but also in the inputs that it receives from structures associated with motor functions such as the globus pallidus and substantia nigra.

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25.

A patient is confused and displays localized jerks in his right hand, which progress to jerks of the entire arm with a brief loss of consciousness. This disorder can best be characterized as which type of seizure?
- A.
  
  Generalized seizure
- B.
  
  Absence seizure
- C.
  
  Simple partial seizure
- D.
  
  Complex partial seizure
- E.
  
  Petit mal seizure
Correct Answer
D. Complex partial seizure

Explanation
This person displays a complex partial seizure, which is characterized by a confusional state with brief losses of consciousness. It is called a partial seizure because the seizure involves a localized region, reflected by jerks of the muscles of a specific part of the body. The focus of this seizure is typically in the temporal lobe, such as the amygdala, hippocampal formation, or adjoining cortical regions. A simple partial seizure does not involve loss of consciousness. Absence seizures are nonconvulsive seizures and are also called petit mal seizures. Generalized seizures typically involve all of the limbs. The patient falls to the ground and loses consciousness.

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26.

The display shown by this patient is then followed by his falling to the ground with a further loss of consciousness in which all of his extremities are extended and are rigid, and jerks of these limbs are displayed as well. This disorder would best be characterized as which type of seizure?
- A.
  
  Generalized seizure
- B.
  
  Absence seizure
- C.
  
  Simple partial seizure
- D.
  
  Complex partial seizure
- E.
  
  Petit mal seizure
Correct Answer
A. Generalized seizure

Explanation
The seizure described in this patient has progressed from a complex partial seizure to a generalized seizure. As indicated previously, this type of seizure involves all of the limbs. The patient falls to the ground and typically loses consciousness. The other choices involve seizures that are characterized differently than what was described in the progression of this case.

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27.

June is a 65-year-old woman who was previously healthy. One day, while taking a walk in the park, she noticed her right fingers twitching, then her right hand, then her arm and shoulder, followed by a march of twitches down her leg. She did not remember any more than this, because she lost consciousness. An onlooker saw her drop to the ground and deviate her neck backward, while making a high-pitched noise. Then, both of her arms and legs began to jerk for approximately 1 to 2 minutes, then stopped abruptly. She had lost control of her bladder during this event. When the onlooker attempted to speak to June to ask her if she was okay, she was unresponsive. The onlooker called an ambulance, which brought June to the nearest hospital. A doctor met June at the emergency room entrance, and asked her what had happened. By this time, June was slightly drowsy, but able to answer questions appropriately. Her speech was fluent and grammatically correct. She knew the month, but not the day of the week, or where she was. She moved the left side of her body better than her right, but had too much difficulty following commands for an effective motor examination. The remainder of her examination was normal. The doctor ordered a CT of June's head, and drew some blood. From which area of the brain did June's seizure begin?
- A.
  
  Left precentral gyrus
- B.
  
  Right precentral gyrus
- C.
  
  Right temporal lobe
- D.
  
  Left temporal lobe
- E.
  
  Thalamus
Correct Answer
A. Left precentral gyrus

Explanation
June had a seizure, which began focally on the left motor strip (the left precentral gyrus), moved up the motor strip, then secondarily generalized, or spread throughout the cortex. The phenomenon whereby there is twitching of an extremity that spreads to other areas on that extremity or other areas of the body is called a Jacksonian march. This phenomenon is named for Hughlings Jackson, a neurosurgeon who was instrumental in mapping out the cerebral cortex and describing the somatotopic organization of the cortex of the prefrontal gyrus called a homunculus (meaning little man). Observing patients with a Jacksonian march helped him to identify areas represented at each location of the motor strip.

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28.

June is a 65-year-old woman who was previously healthy. One day, while taking a walk in the park, she noticed her right fingers twitching, then her right hand, then her arm and shoulder, followed by a march of twitches down her leg. She did not remember any more than this, because she lost consciousness. An onlooker saw her drop to the ground and deviate her neck backward, while making a high-pitched noise. Then, both of her arms and legs began to jerk for approximately 1 to 2 minutes, then stopped abruptly. She had lost control of her bladder during this event. When the onlooker attempted to speak to June to ask her if she was okay, she was unresponsive. The onlooker called an ambulance, which brought June to the nearest hospital. A doctor met June at the emergency room entrance, and asked her what had happened. By this time, June was slightly drowsy, but able to answer questions appropriately. Her speech was fluent and grammatically correct. She knew the month, but not the day of the week, or where she was. She moved the left side of her body better than her right, but had too much difficulty following commands for an effective motor examination. The remainder of her examination was normal. The doctor ordered a CT of June's head, and drew some blood. What could account for June's loss of consciousness following the seizure?
- A.
  
  Involvement of the reticular activating system
- B.
  
  Head trauma
- C.
  
  Bilateral postictal suppression
- D.
  
  Thalamic involvement
- E.
  
  Brain hemorrhage from the seizure
Correct Answer
C. Bilateral postictal suppression

Explanation
Very often, there is inhibition following a seizure, which accounts for drowsiness or a postictal state after the seizure has finished. Sometimes, epileptic discharges spread to other areas of the cortex, recruiting contiguous areas of the cortex through callosal, commissural, and sometimes thalamic circuits to eventually involve a large area of the cortex, causing the movements of the entire body. This occurs with a generalized seizure. If the cortices of both hemispheres become involved, there may be impairment or loss of consciousness. The cells (often pyramidal cells) in the cortex can generate a seizure through high-frequency, synchronous discharges in large groups. If the seizure begins focally, as this one did, there may be a Todd's paralysis, as June had, where there is transient paralysis of the involved motor area during the postictal period.

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29.

June is a 65-year-old woman who was previously healthy. One day, while taking a walk in the park, she noticed her right fingers twitching, then her right hand, then her arm and shoulder, followed by a march of twitches down her leg. She did not remember any more than this, because she lost consciousness. An onlooker saw her drop to the ground and deviate her neck backward, while making a high-pitched noise. Then, both of her arms and legs began to jerk for approximately 1 to 2 minutes, then stopped abruptly. She had lost control of her bladder during this event. When the onlooker attempted to speak to June to ask her if she was okay, she was unresponsive. The onlooker called an ambulance, which brought June to the nearest hospital. A doctor met June at the emergency room entrance, and asked her what had happened. By this time, June was slightly drowsy, but able to answer questions appropriately. Her speech was fluent and grammatically correct. She knew the month, but not the day of the week, or where she was. She moved the left side of her body better than her right, but had too much difficulty following commands for an effective motor examination. The remainder of her examination was normal. The doctor ordered a CT of June's head, and drew some blood. The "march" of twitching that June experienced can be explained by which of the following
- A.
  
  Proximity of the body part to the spinal cord
- B.
  
  Proximity of the body part to the cerebral cortex
- C.
  
  Somatotopic representation within the brainstem
- D.
  
  Somatotopic representation within the basal ganglia
- E.
  
  Somatotopic representation within the precentral gyrus
Correct Answer
E. Somatotopic representation within the precentral gyrus

Explanation
There is somatotopic organization of the motor strip, and cortical neurons are included among the most likely to generate seizures, making this area the most likely to cause such a pattern

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30.

June is a 65-year-old woman who was previously healthy. One day, while taking a walk in the park, she noticed her right fingers twitching, then her right hand, then her arm and shoulder, followed by a march of twitches down her leg. She did not remember any more than this, because she lost consciousness. An onlooker saw her drop to the ground and deviate her neck backward, while making a high-pitched noise. Then, both of her arms and legs began to jerk for approximately 1 to 2 minutes, then stopped abruptly. She had lost control of her bladder during this event. When the onlooker attempted to speak to June to ask her if she was okay, she was unresponsive. The onlooker called an ambulance, which brought June to the nearest hospital. A doctor met June at the emergency room entrance, and asked her what had happened. By this time, June was slightly drowsy, but able to answer questions appropriately. Her speech was fluent and grammatically correct. She knew the month, but not the day of the week, or where she was. She moved the left side of her body better than her right, but had too much difficulty following commands for an effective motor examination. The remainder of her examination was normal. The doctor ordered a CT of June's head, and drew some blood. Which cell type is the predominant cause of the seizure
- A.
  
  Basket cell
- B.
  
  Purkinje cell
- C.
  
  Stellate cell
- D.
  
  Schwann cell
- E.
  
  Pyramidal cell
Correct Answer
E. Pyramidal cell

Explanation
The pyramidal cell is a cell in the cortex that uses glutamate, an excitatory neurotransmitter, whereas most other types of cortical neurons use GABA, an inhibitory neurotransmitter. The spike, one identifying feature of an epileptic seizure seen on an EEG recorded on the scalp, is initiated by a depolarization shift, which is thought to be generated by EPSPs.

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31.

June is a 65-year-old woman who was previously healthy. One day, while taking a walk in the park, she noticed her right fingers twitching, then her right hand, then her arm and shoulder, followed by a march of twitches down her leg. She did not remember any more than this, because she lost consciousness. An onlooker saw her drop to the ground and deviate her neck backward, while making a high-pitched noise. Then, both of her arms and legs began to jerk for approximately 1 to 2 minutes, then stopped abruptly. She had lost control of her bladder during this event. When the onlooker attempted to speak to June to ask her if she was okay, she was unresponsive. The onlooker called an ambulance, which brought June to the nearest hospital. A doctor met June at the emergency room entrance, and asked her what had happened. By this time, June was slightly drowsy, but able to answer questions appropriately. Her speech was fluent and grammatically correct. She knew the month, but not the day of the week, or where she was. She moved the left side of her body better than her right, but had too much difficulty following commands for an effective motor examination. The remainder of her examination was normal. The doctor ordered a CT of June's head, and drew some blood. A burst of what type of potentials may initiate an epileptic seizure?
- A.
  
  Inhibitory postsynaptic potentials (IPSPs)
- B.
  
  Membrane potentials
- C.
  
  Resting potentials
- D.
  
  Excitatory postsynaptic potentials (EPSPs)
- E.
  
  Nernst potential
Correct Answer
D. Excitatory postsynaptic potentials (EPSPs)

Explanation
Excitatory postsynaptic potentials are considered to be an initiating cellular event for a seizure. To become a seizure, however, the cellular discharges require enhancement and synchronization.

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32.

June is a 65-year-old woman who was previously healthy. One day, while taking a walk in the park, she noticed her right fingers twitching, then her right hand, then her arm and shoulder, followed by a march of twitches down her leg. She did not remember any more than this, because she lost consciousness. An onlooker saw her drop to the ground and deviate her neck backward, while making a high-pitched noise. Then, both of her arms and legs began to jerk for approximately 1 to 2 minutes, then stopped abruptly. She had lost control of her bladder during this event. When the onlooker attempted to speak to June to ask her if she was okay, she was unresponsive. The onlooker called an ambulance, which brought June to the nearest hospital. A doctor met June at the emergency room entrance, and asked her what had happened. By this time, June was slightly drowsy, but able to answer questions appropriately. Her speech was fluent and grammatically correct. She knew the month, but not the day of the week, or where she was. She moved the left side of her body better than her right, but had too much difficulty following commands for an effective motor examination. The remainder of her examination was normal. The doctor ordered a CT of June's head, and drew some blood. Which of the following chemical mechanisms could underlie seizure generation
- A.
  
  Na+ channel blockade
- B.
  
  Gamma -aminobutyric acid (GABA) inhibition
- C.
  
  Glutamate inhibition
- D.
  
  Aspartate inhibition
- E.
  
  Substance P inhibition
Correct Answer
B. Gamma -aminobutyric acid (GABA) inhibition

Explanation
Since seizure generation requires excitation, or a loss of inhibition, the only correct choice is the inhibition of GABA, an inhibitory neurotransmitter. All the other choices cause inhibition only. Many new anticonvulsant medications are currently being designed to either enhance GABA activity, or inhibit the excitatory neurotransmitter, glutamate.

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33.

Helen is a 76-year-old woman who has had high blood pressure and diabetes for more than 10 years. One day, as she was reaching for a jar of flour to make an apple pie, her right side suddenly gave out, and she collapsed. While trying to get up from the floor, she noticed that she was unable to move her right arm or leg. Helen attempted to cry for help because she was unable to reach the telephone; however, her speech was slurred and rather unintelligible. She lay on the floor and waited for help to arrive. Helen's son began to worry about his usually prompt mother when she didn't arrive with her apple pie. After several attempts at telephoning her apartment without an answer, he drove to her apartment and found her lying on the floor. She attempted to tell him what had happened, but her speech was too slurred to comprehend, so assuming that his mother had had a stroke, her son called an ambulance to bring her to the nearest emergency room. A neurology resident was called to see Helen in the emergency room because the physicians there, too, felt that she had had a stroke. The resident noted that Helen followed commands very well, and, although her speech was very slurred, it was fluent and grammatically correct. The lower two-thirds of her face drooped on the right, but when asked to raise her eyebrows, her forehead appeared symmetric. Her tongue pointed to the right side when she was asked to protrude it. Her right arm and leg were severely, but equally, weak; her left side had normal strength. She felt a pin and a vibrating tuning fork equally on both sides. Where in the central nervous system (CNS) did Helen's stroke occur
- A.
  
  Left precentral gyrus
- B.
  
  Right precentral gyrus
- C.
  
  Left basilar pons or left internal capsule
- D.
  
  Right putamen or globus pallidus
- E.
  
  Left thalamus
Correct Answer
C. Left basilar pons or left internal capsule

Explanation
A CT scan of Helen's head was done in the emergency room, which showed a new infarct or stroke in the genu and anterior portion of the posterior limb of the left internal capsule. This is the region of the internal capsule through which most of the fibers of the corticospinal and corticobulbar tracts pass in a somatotopically organized fashion before entering the brainstem. Because most of these fibers pass through a very small region, a small infarct can cause deficits in a wide distribution of areas. In this case, Helen has weakness in her face and tongue, causing her slurred speech, in addition to weakness of her arm and leg. In addition, since somatosensory fibers destined for the postcentral gyrus occupy a position in the internal capsule caudal to the corticospinal tract fibers, these fibers are spared and Helen has no sensory deficits. The only other area in the CNS that can cause a pure motor hemiparesis is the basilar pons, an area through which corticospinal and corticobulbar fibers also run. The vascular supply of this region consists of perforators from the basilar artery, which are small and subject to atherosclerotic disease.

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34.

Helen is a 76-year-old woman who has had high blood pressure and diabetes for more than 10 years. One day, as she was reaching for a jar of flour to make an apple pie, her right side suddenly gave out, and she collapsed. While trying to get up from the floor, she noticed that she was unable to move her right arm or leg. Helen attempted to cry for help because she was unable to reach the telephone; however, her speech was slurred and rather unintelligible. She lay on the floor and waited for help to arrive. Helen's son began to worry about his usually prompt mother when she didn't arrive with her apple pie. After several attempts at telephoning her apartment without an answer, he drove to her apartment and found her lying on the floor. She attempted to tell him what had happened, but her speech was too slurred to comprehend, so assuming that his mother had had a stroke, her son called an ambulance to bring her to the nearest emergency room. A neurology resident was called to see Helen in the emergency room because the physicians there, too, felt that she had had a stroke. The resident noted that Helen followed commands very well, and, although her speech was very slurred, it was fluent and grammatically correct. The lower two-thirds of her face drooped on the right, but when asked to raise her eyebrows, her forehead appeared symmetric. Her tongue pointed to the right side when she was asked to protrude it. Her right arm and leg were severely, but equally, weak; her left side had normal strength. She felt a pin and a vibrating tuning fork equally on both sides. A computerized tomography (CT) scan revealed a new infarct in the left internal capsule. Which artery was occluded, causing the stroke?
- A.
  
  Lenticulostriate branches of the middle cerebral artery
- B.
  
  Posterior cerebral artery
- C.
  
  Anterior cerebral artery
- D.
  
  Vertebral artery
- E.
  
  Posterior choroidal artery
Correct Answer
A. Lenticulostriate branches of the middle cerebral artery

Explanation
The internal capsule is supplied primarily by the lenticulostriate branches of the middle cerebral artery. In addition, portions of the posterior limb of the internal capsule are supplied by the anterior choroidal artery, a branch of the internal carotid artery. Both the lateral striate branches and the anterior choroidal artery are small branches of larger arteries, and are more susceptible to damage (atherosclerosis) from high blood pressure and diabetes than the larger vessels.

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35.

Helen is a 76-year-old woman who has had high blood pressure and diabetes for more than 10 years. One day, as she was reaching for a jar of flour to make an apple pie, her right side suddenly gave out, and she collapsed. While trying to get up from the floor, she noticed that she was unable to move her right arm or leg. Helen attempted to cry for help because she was unable to reach the telephone; however, her speech was slurred and rather unintelligible. She lay on the floor and waited for help to arrive. Helen's son began to worry about his usually prompt mother when she didn't arrive with her apple pie. After several attempts at telephoning her apartment without an answer, he drove to her apartment and found her lying on the floor. She attempted to tell him what had happened, but her speech was too slurred to comprehend, so assuming that his mother had had a stroke, her son called an ambulance to bring her to the nearest emergency room. A neurology resident was called to see Helen in the emergency room because the physicians there, too, felt that she had had a stroke. The resident noted that Helen followed commands very well, and, although her speech was very slurred, it was fluent and grammatically correct. The lower two-thirds of her face drooped on the right, but when asked to raise her eyebrows, her forehead appeared symmetric. Her tongue pointed to the right side when she was asked to protrude it. Her right arm and leg were severely, but equally, weak; her left side had normal strength. She felt a pin and a vibrating tuning fork equally on both sides. Damage to which two tracts caused Helen to be weak on her right side?
- A.
  
  Spinothalamic and corticospinal tracts
- B.
  
  Spinothalamic and corticobulbar tracts
- C.
  
  Corticospinal and corticobulbar tracts
- D.
  
  Corticospinal and spinocerebellar tracts
- E.
  
  Corticospinal and rubrospinal tracts
Correct Answer
C. Corticospinal and corticobulbar tracts

Explanation
The corticospinal and corticobulbar tracts contain motor fibers originating in the precentral gyrus, mediating voluntary motor function of the face, arms, legs, and trunk. They pass through the internal capsule to the crus cerebri in the midbrain. The spinothalamic tract is a sensory tract, and could not cause the observed deficits. The rubrospinal tract only affects the spinal cord.

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36.

Helen is a 76-year-old woman who has had high blood pressure and diabetes for more than 10 years. One day, as she was reaching for a jar of flour to make an apple pie, her right side suddenly gave out, and she collapsed. While trying to get up from the floor, she noticed that she was unable to move her right arm or leg. Helen attempted to cry for help because she was unable to reach the telephone; however, her speech was slurred and rather unintelligible. She lay on the floor and waited for help to arrive. Helen's son began to worry about his usually prompt mother when she didn't arrive with her apple pie. After several attempts at telephoning her apartment without an answer, he drove to her apartment and found her lying on the floor. She attempted to tell him what had happened, but her speech was too slurred to comprehend, so assuming that his mother had had a stroke, her son called an ambulance to bring her to the nearest emergency room. A neurology resident was called to see Helen in the emergency room because the physicians there, too, felt that she had had a stroke. The resident noted that Helen followed commands very well, and, although her speech was very slurred, it was fluent and grammatically correct. The lower two-thirds of her face drooped on the right, but when asked to raise her eyebrows, her forehead appeared symmetric. Her tongue pointed to the right side when she was asked to protrude it. Her right arm and leg were severely, but equally, weak; her left side had normal strength. She felt a pin and a vibrating tuning fork equally on both sides. How can Helen's speech deficit be classified
- A.
  
  Wernicke's aphasia
- B.
  
  Broca's aphasia
- C.
  
  Anomia
- D.
  
  Dysarthria
- E.
  
  Conduction aphasia
Correct Answer
D. Dysarthria

Explanation
Dysarthria is slurred speech, occurring from lesions affecting innervation of the tongue, lips, and palate. We are given evidence that her tongue is weak in that her tongue points to the right. The interruption of fibers traveling to the hypoglossal nerve from the left side eventually innervates the right genioglossus muscle, which pulls the tongue to the left. Dysarthria is a motor phenomenon, unlike aphasia, which is a disruption of language. Language is primarily generated in the cerebral cortex; therefore, because the lesion spares the cortex, there were no signs of aphasia.

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37.

Lindsey is a 12-year-old girl who has never had medical problems. One day, while in the kitchen with her mother, she told her mother that she felt very frightened all of a sudden and had a funny feeling in her stomach. Immediately after this, she turned her head to the right, stared persistently, and began to chew. Her mother called her name several times, but Lindsey, who was usually a very obedient child, did not answer. After approximately 1 minute of staring, Lindsey slowly turned her head back to her mother. Apparently confused, she asked her mother where she was. Over the next 10 to 15 minutes, she became less and less confused, and by the time she was in the car being driven to the pediatrician by her mother, she felt like she was back to normal. The pediatrician listened to Lindsey's mother's story when they arrived. He examined Lindsey and could find no abnormalities on general physical examination or on neurologic examination. The pediatrician told her mother that he would refer Lindsey to a pediatric neurologist for further evaluation, as well as further evaluation for the need for medication. What type of problem did Lindsey most likely have
- A.
  
  Attention deficit disorder (ADD)
- B.
  
  Temporary psychosis
- C.
  
  Conversion disorder
- D.
  
  Epilepsy
- E.
  
  Schizophrenia
Correct Answer
D. Epilepsy

Explanation
This is an example of a complex partial seizure, most likely originating in the temporal lobe. A seizure is a paroxysmal derangment of the CNS due to rhythmic, synchronous discharges from cerebral neurons, causing changes in consciousness, sensation, and/or behavior. Complex partial seizures often start with a warning, or "aura." Since limbic structures are often involved, the seizure can include emotions, feelings of deja vu or jamais vu, or gastrointestinal sensations. Because olfactory pathways end in the temporal lobe, patients may experience smells as well. The seizure, itself, involves impairment of consciousness of some form, often manifested as staring, in addition to various stereotyped, automatic behaviors called automatisms. The latter may be manifested as chewing, repetitive swallowing, hand gestures, or vocalizations. These usually occur during the seizure, but may occur after it. After the seizure ends (the seizures usually last 1 to 2 minutes), the patient is often in a confused or postictal state for several minutes, or even up to several hours. Occasionally, a patient may manifest aggressive behavior while in the postictal state. Unless a structural lesion, such as a tumor, is present, the physical examination is usually normal. Verification of the diagnosis of epilepsy is done with the help of an EEG, which records potential differences of summed cortical action potentials over the scalp of a patient. Often, an epileptic spike, or sharp wave, is seen over the area from which the seizures arise. Epilepsy patients usually also have a CT scan or MRI to make certain that there is no structural lesion causing the seizures.

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38.

Lindsey is a 12-year-old girl who has never had medical problems. One day, while in the kitchen with her mother, she told her mother that she felt very frightened all of a sudden and had a funny feeling in her stomach. Immediately after this, she turned her head to the right, stared persistently, and began to chew. Her mother called her name several times, but Lindsey, who was usually a very obedient child, did not answer. After approximately 1 minute of staring, Lindsey slowly turned her head back to her mother. Apparently confused, she asked her mother where she was. Over the next 10 to 15 minutes, she became less and less confused, and by the time she was in the car being driven to the pediatrician by her mother, she felt like she was back to normal. The pediatrician listened to Lindsey's mother's story when they arrived. He examined Lindsey and could find no abnormalities on general physical examination or on neurologic examination. The pediatrician told her mother that he would refer Lindsey to a pediatric neurologist for further evaluation, as well as further evaluation for the need for medication. From which area of the brain is this problem most likely emanating
- A.
  
  Medulla
- B.
  
  Occipital lobe
- C.
  
  Temporal lobe
- D.
  
  Thalamus
- E.
  
  Midbrain
Correct Answer
C. Temporal lobe

Explanation
Seizures similar to this one often begin with abnormal neuronal discharges in temporal lobe structures, which include the amygdala or hippocampus. These structures tend to have a lower threshold for this type of activity than other structures in the brain.

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39.

Lindsey is a 12-year-old girl who has never had medical problems. One day, while in the kitchen with her mother, she told her mother that she felt very frightened all of a sudden and had a funny feeling in her stomach. Immediately after this, she turned her head to the right, stared persistently, and began to chew. Her mother called her name several times, but Lindsey, who was usually a very obedient child, did not answer. After approximately 1 minute of staring, Lindsey slowly turned her head back to her mother. Apparently confused, she asked her mother where she was. Over the next 10 to 15 minutes, she became less and less confused, and by the time she was in the car being driven to the pediatrician by her mother, she felt like she was back to normal. The pediatrician listened to Lindsey's mother's story when they arrived. He examined Lindsey and could find no abnormalities on general physical examination or on neurologic examination. The pediatrician told her mother that he would refer Lindsey to a pediatric neurologist for further evaluation, as well as further evaluation for the need for medication. If the amygdala is involved with this problem, which two major efferent pathways from this structure may be affected
- A.
  
  Corticospinal tract and stria terminalis
- B.
  
  Mamillothalamic tract and stria terminalis
- C.
  
  Medial forebrain bundle and stria terminalis
- D.
  
  Ventral amygdalofugal pathway and stria terminalis
- E.
  
  Corticospinal tract and mamillothalamic tract
Correct Answer
D. Ventral amygdalofugal pathway and stria terminalis

Explanation
The major descending pathways from the amygdala are the stria terminalis and the ventral amygdalofugal pathway. The medial forebrain bundle is a major pathway of the lateral hypothalamus. The mamillothalamic and corticospinal tracts do not involve the amygdala.

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40.

Lindsey is a 12-year-old girl who has never had medical problems. One day, while in the kitchen with her mother, she told her mother that she felt very frightened all of a sudden and had a funny feeling in her stomach. Immediately after this, she turned her head to the right, stared persistently, and began to chew. Her mother called her name several times, but Lindsey, who was usually a very obedient child, did not answer. After approximately 1 minute of staring, Lindsey slowly turned her head back to her mother. Apparently confused, she asked her mother where she was. Over the next 10 to 15 minutes, she became less and less confused, and by the time she was in the car being driven to the pediatrician by her mother, she felt like she was back to normal. The pediatrician listened to Lindsey's mother's story when they arrived. He examined Lindsey and could find no abnormalities on general physical examination or on neurologic examination. The pediatrician told her mother that he would refer Lindsey to a pediatric neurologist for further evaluation, as well as further evaluation for the need for medication. If the hippocampal formation is involved in this problem, which structures may be damaged?
- A.
  
  Hippocampus, dentate gyrus, and subiculum
- B.
  
  Hippocampus, amygdala, and subiculum
- C.
  
  Hippocampus, fornix, and amygdala
- D.
  
  Hippocampus, fornix, and habenulae
- E.
  
  Hippocampus, dentate gyrus, and fornix
Correct Answer
A. Hippocampus, dentate gyrus, and subiculum

Explanation
The hippocampal formation includes the hippocampus, the dentate gyrus, and the subiculum. All of the other structures listed are within the limbic system, but do not lie within the hippocampal formation

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41.

Lindsey is a 12-year-old girl who has never had medical problems. One day, while in the kitchen with her mother, she told her mother that she felt very frightened all of a sudden and had a funny feeling in her stomach. Immediately after this, she turned her head to the right, stared persistently, and began to chew. Her mother called her name several times, but Lindsey, who was usually a very obedient child, did not answer. After approximately 1 minute of staring, Lindsey slowly turned her head back to her mother. Apparently confused, she asked her mother where she was. Over the next 10 to 15 minutes, she became less and less confused, and by the time she was in the car being driven to the pediatrician by her mother, she felt like she was back to normal. The pediatrician listened to Lindsey's mother's story when they arrived. He examined Lindsey and could find no abnormalities on general physical examination or on neurologic examination. The pediatrician told her mother that he would refer Lindsey to a pediatric neurologist for further evaluation, as well as further evaluation for the need for medication. If Lindsey develops this problem with a high frequency, what ongoing problem may she eventually develop
- A.
  
  Hemiparesis
- B.
  
  Diminished memory function
- C.
  
  Diminished sensation
- D.
  
  Improved attention
- E.
  
  Dyslexia
Correct Answer
B. Diminished memory function

Explanation
Since memory is a function that is mediated by the limbic system, a structure most likely involved in the generation of these seizures, it is possible that Lindsey will have memory problems in the future if she has frequent seizures. Early studies of patients who have undergone resection of portions of one or both temporal lobes have demonstrated the presence of memory deficits.

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42.

Morris is a 79-year-old man who was brought to the emergency room (ER) because his family was worried that he suddenly was not using his right arm and leg, and seemed to have a simultaneous behavior change. He was unable to write a reminder note to himself, even with his left hand, and he put his shoes on the wrong feet. A neurologist was called to the ER to examine the patient. A loud bruit (pronounced as bru-¯e; a rumbling sound) was heard with a stethoscope over the left carotid artery in his neck. When asked to show the neurologist his left hand, he pointed to his right hand, since it could not move. The neurologist asked him to add numbers, and he was unable to do this, despite having spent his life as a bookkeeper. Morris was unable to name the fingers on either hand, and he could not form any semblance of a letter, using his left hand. His eyes did not blink when the neurologist waved his hands close to Morris' eyes in the left temporal and right nasal visual fields. The right lower two-thirds of his face drooped. There was some asymmetry of his reflexes between the right and left sides, and there was a positive Babinski response of his right toe. Where in the CNS is the damage?
- A.
  
  Right frontal and parietal lobes
- B.
  
  Left frontal and parietal lobes
- C.
  
  Right frontal lobe
- D.
  
  Left frontal lobe
- E.
  
  Right temporal lobe
Correct Answer
B. Left frontal and parietal lobes

Explanation
This case is an example of a lesion of the left (usually dominant) parietal lobe, most often in the angular gyrus, with some involvement of the precentral gyrus in the posterior frontal lobe. There is contralateral UMN weakness (with a positive Babinski sign), as well as several cortical sensory defects—specifically, right-left confusion, agraphia (inability to write, independent of motor weakness), acalculia (the inability to calculate), and finger agnosia (the inability to designate the fingers). The latter four elements are sometimes referred to as the Gerstmann syndrome by neurologists, and all represent spatial discriminatory functions of the parietal lobe (often the dominant parietal lobe, which is usually the left). The parietal lobe also subserves other visual-spatial functions such as construction of complex drawings. There are other locations within the CNS where UMN weakness can occur; however, the combination with parietal lobe signs can only occur in this location. If the damage was slightly more extensive, it may have involved Broca's area, causing aphasia.

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43.

Morris is a 79-year-old man who was brought to the emergency room (ER) because his family was worried that he suddenly was not using his right arm and leg, and seemed to have a simultaneous behavior change. He was unable to write a reminder note to himself, even with his left hand, and he put his shoes on the wrong feet. A neurologist was called to the ER to examine the patient. A loud bruit (pronounced as bru-¯e; a rumbling sound) was heard with a stethoscope over the left carotid artery in his neck. When asked to show the neurologist his left hand, he pointed to his right hand, since it could not move. The neurologist asked him to add numbers, and he was unable to do this, despite having spent his life as a bookkeeper. Morris was unable to name the fingers on either hand, and he could not form any semblance of a letter, using his left hand. His eyes did not blink when the neurologist waved his hands close to Morris' eyes in the left temporal and right nasal visual fields. The right lower two-thirds of his face drooped. There was some asymmetry of his reflexes between the right and left sides, and there was a positive Babinski response of his right toe. Assuming that Morris had a stroke, which artery has become occluded?
- A.
  
  Left anterior cerebral
- B.
  
  Right anterior cerebral
- C.
  
  Left middle cerebral
- D.
  
  Right middle cerebral
- E.
  
  Left posterior cerebral
Correct Answer
D. Right middle cerebral

Explanation
The artery serving this region (both posterior frontal and parietal lobes) is the right middle cerebral artery, which originates at Willis's circle. Because it continues in a nearly straight line from the internal carotid artery, it is a common route for small emboli formed from blood clots in the internal carotid artery. The bruit noted over the right common carotid artery in this patient is most likely a result of a thrombus (clot) that occludes part of the lumen of the artery. These emboli can occlude the middle cerebral artery because it is considerably smaller than the internal carotid artery. Since the middle cerebral artery has many branches through which an embolus may travel, but the territory of this stroke is large, it is likely that the embolus lodged in a more proximal location in this case.

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44.

Morris is a 79-year-old man who was brought to the emergency room (ER) because his family was worried that he suddenly was not using his right arm and leg, and seemed to have a simultaneous behavior change. He was unable to write a reminder note to himself, even with his left hand, and he put his shoes on the wrong feet. A neurologist was called to the ER to examine the patient. A loud bruit (pronounced as bru-¯e; a rumbling sound) was heard with a stethoscope over the left carotid artery in his neck. When asked to show the neurologist his left hand, he pointed to his right hand, since it could not move. The neurologist asked him to add numbers, and he was unable to do this, despite having spent his life as a bookkeeper. Morris was unable to name the fingers on either hand, and he could not form any semblance of a letter, using his left hand. His eyes did not blink when the neurologist waved his hands close to Morris' eyes in the left temporal and right nasal visual fields. The right lower two-thirds of his face drooped. There was some asymmetry of his reflexes between the right and left sides, and there was a positive Babinski response of his right toe. Damage to which area of the brain caused Morris' inability to move his right side?
- A.
  
  Right precentral gyrus
- B.
  
  Left precentral gyrus
- C.
  
  Right angular gyrus
- D.
  
  Left angular gyrus
- E.
  
  Left supramarginal gyrus
Correct Answer
B. Left precentral gyrus

Explanation
Morris' leg weakness includes a positive Babinski sign, which is a UMN sign. Although this type of weakness may occur in several locations in the CNS, the combination with the cortical parietal signs can only occur in the left precentral gyrus if there is to be one lesion.

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45.

Morris is a 79-year-old man who was brought to the emergency room (ER) because his family was worried that he suddenly was not using his right arm and leg, and seemed to have a simultaneous behavior change. He was unable to write a reminder note to himself, even with his left hand, and he put his shoes on the wrong feet. A neurologist was called to the ER to examine the patient. A loud bruit (pronounced as bru-¯e; a rumbling sound) was heard with a stethoscope over the left carotid artery in his neck. When asked to show the neurologist his left hand, he pointed to his right hand, since it could not move. The neurologist asked him to add numbers, and he was unable to do this, despite having spent his life as a bookkeeper. Morris was unable to name the fingers on either hand, and he could not form any semblance of a letter, using his left hand. His eyes did not blink when the neurologist waved his hands close to Morris' eyes in the left temporal and right nasal visual fields. The right lower two-thirds of his face drooped. There was some asymmetry of his reflexes between the right and left sides, and there was a positive Babinski response of his right toe. Damage to which region caused Morris' inability to tell right from left and inability to write, even with his nondominant hand?
- A.
  
  Left parietal
- B.
  
  Left frontal
- C.
  
  Right frontal
- D.
  
  Left temporal
- E.
  
  Right temporal
Correct Answer
A. Left parietal

Explanation
These deficits are visual-spatial in nature, and are characteristic of damage to the dominant parietal lobe.

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46.

Morris is a 79-year-old man who was brought to the emergency room (ER) because his family was worried that he suddenly was not using his right arm and leg, and seemed to have a simultaneous behavior change. He was unable to write a reminder note to himself, even with his left hand, and he put his shoes on the wrong feet. A neurologist was called to the ER to examine the patient. A loud bruit (pronounced as bru-¯e; a rumbling sound) was heard with a stethoscope over the left carotid artery in his neck. When asked to show the neurologist his left hand, he pointed to his right hand, since it could not move. The neurologist asked him to add numbers, and he was unable to do this, despite having spent his life as a bookkeeper. Morris was unable to name the fingers on either hand, and he could not form any semblance of a letter, using his left hand. His eyes did not blink when the neurologist waved his hands close to Morris' eyes in the left temporal and right nasal visual fields. The right lower two-thirds of his face drooped. There was some asymmetry of his reflexes between the right and left sides, and there was a positive Babinski response of his right toe. Damage to which structure caused the visual defect?
- A.
  
  Right optic nerve
- B.
  
  Left optic nerve
- C.
  
  Optic chiasm
- D.
  
  Right optic radiations
- E.
  
  Left optic radiations
Correct Answer
E. Left optic radiations

Explanation
The visual defect that Morris experiences is a homonymous hemianopsia, resulting from damage to the optic radiations traveling from the lateral geniculate nucleus to the visual cortex in the occipital lobe. These split so that inferior images are carried through the parietal lobe and superior images through the temporal lobes, but in large infarcts, the defect is more likely to involve more fibers of this tract. Since the optic radiations carry representations of the ipsilateral temporal field and the contralateral nasal field (only the nasal field fibers cross), this defect is noted clinically as the inability to detect objects in the regions described. Often, the patient will only notice bumping into objects on the side ipsilateral to the stroke, since turning of the eyes can compensate for the nasal field defect.

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47.

Joe is a 75-year-old man who is right-handed and was told in the past by his internist that he had an irregular heartbeat. Unfortunately, Joe decided that he didn't wish to learn anything further about this condition, so he didn't return to this physician, and it remained untreated. One morning, he awoke to find that his face drooped on the right side, and that he couldn't move his right arm or right leg. When he tried to call an ambulance for help, he had a great deal of difficulty communicating with the operator because his speech was slurred, nonfluent, and missing some pronouns. The call was traced by the police, and an ambulance arrived at his house and brought him to an emergency room. A neurologist was called to see Joe in the emergency room. When he listened to Joe's heart, he detected an irregular heartbeat. It was very difficult to understand Joe's speech, because it was halting, with a tendency to repeat the same phrases over and over. He had a great deal of difficulty repeating specific sentences given to him by the neurologist, but he was able to follow simple commands, such as: "Touch your right ear with your left hand." His mouth drooped on the right when he attempted to smile, but his forehead remained symmetric when he wrinkled it. He couldn't move his right arm at all, but was able to wiggle his right leg a little bit. What kind of language problem does Joe have?
- A.
  
  Dysarthria
- B.
  
  Wernicke's aphasia
- C.
  
  Broca's aphasia
- D.
  
  Alexia
- E.
  
  Pure word deafness
Correct Answer
C. Broca's aphasia

Explanation
The language problem is an example of Broca's aphasia, a deficit seen with lesions of Broca's area and manifested by defects in the motor aspect of speech, leaving the patient's speech halting and nonfluent. People with Broca's aphasia tend to repeat certain phrases, as well as leave out pronouns. Since the language centers are usually located on the dominant side of the brain (the left side for a right-handed person), this lesion must be on the left side of Joe's brain. Wernicke's aphasia is a problem with the sensory aspect of speech, where the patient can speak fluently, but the speech sounds like gibberish. The area of disruption in this type of aphasia is usually in Wernicke's area, a region of the posterior superior temporal lobe. Dysarthria is slurred speech, but makes grammatical sense. Alexia is the inability to read. Pure-word deafness is a type of sensory aphasia where language, reading, and writing are only mildly disturbed, but auditory comprehension of words is very abnormal. This arises from lesions of the posterior temporal lobe.

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48.

Joe is a 75-year-old man who is right-handed and was told in the past by his internist that he had an irregular heartbeat. Unfortunately, Joe decided that he didn't wish to learn anything further about this condition, so he didn't return to this physician, and it remained untreated. One morning, he awoke to find that his face drooped on the right side, and that he couldn't move his right arm or right leg. When he tried to call an ambulance for help, he had a great deal of difficulty communicating with the operator because his speech was slurred, nonfluent, and missing some pronouns. The call was traced by the police, and an ambulance arrived at his house and brought him to an emergency room. A neurologist was called to see Joe in the emergency room. When he listened to Joe's heart, he detected an irregular heartbeat. It was very difficult to understand Joe's speech, because it was halting, with a tendency to repeat the same phrases over and over. He had a great deal of difficulty repeating specific sentences given to him by the neurologist, but he was able to follow simple commands, such as: "Touch your right ear with your left hand." His mouth drooped on the right when he attempted to smile, but his forehead remained symmetric when he wrinkled it. He couldn't move his right arm at all, but was able to wiggle his right leg a little bit. Which area of the brain is damaged?
- A.
  
  Internal capsule and thalamus
- B.
  
  Right occipital lobe
- C.
  
  Pontine reticular formation
- D.
  
  Corpus callosum
- E.
  
  Left precentral gyrus and Broca's area
Correct Answer
E. Left precentral gyrus and Broca's area

Explanation
Joe's condition is an example of a left inferior frontal lobe cortical stroke, including the region of Broca's area and the left precentral gyrus. The weakness on his right side confirms this, since the left side of the brain controls the right side of the body. The right leg is most likely less involved than the arm because the leg area of the precentral gyrus extends onto the medial aspect of the frontal lobe, an area served by a different artery than that serving the arm and face areas. The internal capsule contains motor fibers traveling to the cortex, but usually does not involve language. The thalamus contains many sensory, motor, and association areas, but only rarely causes language problems. Functions of the pontine reticular formation do not include language. The corpus callosum is a white matter structure that connects the hemispheres. Lesions of the posterior aspect may cause language problems, such as alexia without agraphia (the ability to write, but not to read), but would not cause both an aphasia as well as weakness.

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49.

Joe is a 75-year-old man who is right-handed and was told in the past by his internist that he had an irregular heartbeat. Unfortunately, Joe decided that he didn't wish to learn anything further about this condition, so he didn't return to this physician, and it remained untreated. One morning, he awoke to find that his face drooped on the right side, and that he couldn't move his right arm or right leg. When he tried to call an ambulance for help, he had a great deal of difficulty communicating with the operator because his speech was slurred, nonfluent, and missing some pronouns. The call was traced by the police, and an ambulance arrived at his house and brought him to an emergency room. A neurologist was called to see Joe in the emergency room. When he listened to Joe's heart, he detected an irregular heartbeat. It was very difficult to understand Joe's speech, because it was halting, with a tendency to repeat the same phrases over and over. He had a great deal of difficulty repeating specific sentences given to him by the neurologist, but he was able to follow simple commands, such as: "Touch your right ear with your left hand." His mouth drooped on the right when he attempted to smile, but his forehead remained symmetric when he wrinkled it. He couldn't move his right arm at all, but was able to wiggle his right leg a little bit. Which artery was blocked when the event occurred
- A.
  
  Anterior cerebral artery
- B.
  
  Posterior cerebral artery
- C.
  
  Anterior inferior cerebellar artery
- D.
  
  Middle cerebral artery
- E.
  
  Basilar artery
Correct Answer
D. Middle cerebral artery

Explanation
The middle cerebral artery subserves the precentral gyrus, the area which has been damaged. The damage can be more widespread, depending upon which portion of the vessel becomes occluded. The anterior cerebral artery supplies the orbitofrontal cortex, deep limbic structures, as well as the cingulate gyrus. The posterior cerebral artery supplies the thalamus, portions of the temporal lobes, and portions of the midbrain. The anterior inferior cerebellar artery supplies the lateral inferior pons and portions of the cerebellum. Perforating branches of the basilar artery supply medial portions of the brainstem. The irregular heartbeat observed in this case is an example of aerial fibrillation, a heart rhythm that is often recognized by being "irregularly irregular". This rhythm can cause strokes by throwing small blood clots or emboli from the heart to the cerebral blood vessels and occluding them.

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50.

Joe is a 75-year-old man who is right-handed and was told in the past by his internist that he had an irregular heartbeat. Unfortunately, Joe decided that he didn't wish to learn anything further about this condition, so he didn't return to this physician, and it remained untreated. One morning, he awoke to find that his face drooped on the right side, and that he couldn't move his right arm or right leg. When he tried to call an ambulance for help, he had a great deal of difficulty communicating with the operator because his speech was slurred, nonfluent, and missing some pronouns. The call was traced by the police, and an ambulance arrived at his house and brought him to an emergency room. A neurologist was called to see Joe in the emergency room. When he listened to Joe's heart, he detected an irregular heartbeat. It was very difficult to understand Joe's speech, because it was halting, with a tendency to repeat the same phrases over and over. He had a great deal of difficulty repeating specific sentences given to him by the neurologist, but he was able to follow simple commands, such as: "Touch your right ear with your left hand." His mouth drooped on the right when he attempted to smile, but his forehead remained symmetric when he wrinkled it. He couldn't move his right arm at all, but was able to wiggle his right leg a little bit. Which term best describes Joe's facial weakness?
- A.
  
  Peripheral nerve VII
- B.
  
  Central nerve VII
- C.
  
  Nerve XII
- D.
  
  Nerve V
- E.
  
  Oculomotor nerve weakness
Correct Answer
B. Central nerve VII

Explanation
Joe's forehead doesn't droop like the rest of his face because this region receives innervation from both sides of the cerebral cortex, giving this area a backup in case of damage. This can only occur when the lesion is above the level of nerve VII, where both sides no longer contribute to the innervation of the face. This type of weakness is called a central nerve VII lesion, because it occurs within the CNS. A peripheral nerve VII lesion is a lesion within the nerve VII nucleus, or distal. This type of lesion always involves the forehead in addition to the rest of the face. Nerve XII innervates the tongue, nerve V innervates sensation of the face, in addition to the muscles of mastication, but not the muscles of facial expression. The oculomotor nerve innervates four of the muscles that move the eyes.

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USMLE Step 1 Qs (9)

A 67-year-old man suffers an infarct of the geniculothalamic branch of the posterior cerebral artery. In particular, there is involvement of nuclei of the posterior thalamus. Which of the following is the most likely effect of such an infarct

A 67-year-old man suffers an infarct of the geniculothalamic branch of the posterior cerebral artery. In particular, there is involvement of nuclei of the posterior thalamus. The neurons affected by this infarction project primarily to which of the following?

A 52-year-old woman has an infarct involving a branch of the posterior communicating artery, causing damage to the ventral anterior (VA), ventrolateral (VL), dorsomedial, and anterior thalamic nuclei. Which of the following is the most likely clinical manifestations of this infarct

A 52-year-old woman has an infarct involving a branch of the posterior communicating artery, causing damage to the ventral anterior (VA), ventrolateral (VL), dorsomedial, and anterior thalamic nuclei. The VA nucleus receives inputs primarily from structures associated with which of the following?

A 52-year-old woman has an infarct involving a branch of the posterior communicating artery, causing damage to the ventral anterior (VA), ventrolateral (VL), dorsomedial, and anterior thalamic nuclei. The primary outputs of the VA nucleus include which of the following?

A patient is confused and displays localized jerks in his right hand, which progress to jerks of the entire arm with a brief loss of consciousness. This disorder can best be characterized as which type of seizure?

The display shown by this patient is then followed by his falling to the ground with a further loss of consciousness in which all of his extremities are extended and are rigid, and jerks of these limbs are displayed as well. This disorder would best be characterized as which type of seizure?