1.
A 69-year-old man is brought to the emergency department with the complaint of a sudden loss of sensation. The history reveals that the man is overweight, hypertensive ,and does not regularly take medication. When the man speaks his voice is gravely and hoarse. The examination further reveals a loss of pain and thermal sensations on the right side of his body and on the left side of his face. CT shows an infarcted area in the medulla.
Damage to which of the following structures would most likely explain the man’s hoarse, gravelly voice?
Correct Answer
D. Nucleus ambiguus
Explanation
The vocalis muscle (this muscle is actually the medial portion of the thyroarytenoid muscle) is innervated, via the vagus nerve, by motor neurons located in the nucleus ambiguus. The gracile nucleus conveys sensory input from the body and the spinal trigeminal nucleus relays sensory input from the face. The hypoglossal nucleus is motor to the tongue and the facial nucleus is motor to the muscles of facial expression.(p.104–109,112)
2.
A 69-year-old man is brought to the emergency department with the complaint of a sudden loss of sensation. The history reveals that the man is overweight, hypertensive ,and does not regularly take medication. When the man speaks his voice is gravely and hoarse. The examination further reveals a loss of pain and thermal sensations on the right side of his body and on the left side of his face. CT shows an infarcted area in the medulla.
Injury to which of the following structures in this man is most specifically related to the loss of pain and thermal sensations on the body below the neck?
Correct Answer
A. Anterolateral system
Explanation
Fibers comprising the anterolateral system convey pain and thermal sensations from the body, excluding the face. These fibers are located in lateral portions of the medulla adjacent to the spinal trigeminal tract; this latter tract relays pain and thermal sensations from the face. The gracile and cuneatefasciculi convey proprioception, discriminative touch, and vibratory sense in the spinal cord and the medial lemniscus conveys this same information from the medulla to the dorsal thalamus.(p.104–109,112)
3.
A 69-year-old man is brought to the emergency department with the complaint of a sudden loss of sensation. The history reveals that the man is overweight, hypertensive ,and does not regularly take medication. When the man speaks his voice is gravely and hoarse. The examination further reveals a loss of pain and thermal sensations on the right side of his body and on the left side of his face. CT shows an infarcted area in the medulla.
Damage to which of the following structures would most specifically explain the loss of pain and thermal sensations on the man’s face?
Correct Answer
E. Spinal trigeminal tract
Explanation
The loss of pain and thermal sensations on one side of the face correlates with damage to the spinal trigeminal tract; in this case the loss is ipsilateral to the lesion. The anterolateral system relays pain and thermal sensations from the contralateral side of the body, the solitary tract conveys visceral sensory input (especially taste),and the medial lemniscus contains fibers relaying information related to position sense and dis-criminative touch. The medial longitudinal fasciculus does not contain sensory fibers.(p.104–109,112)
4.
A 69-year-old man is brought to the emergency department with the complaint of a sudden loss of sensation. The history reveals that the man is overweight, hypertensive ,and does not regularly take medication. When the man speaks his voice is gravely and hoarse. The examination further reveals a loss of pain and thermal sensations on the right side of his body and on the left side of his face. CT shows an infarcted area in the medulla.
The CT shows an infarcted area in the medulla in this man. Based on the deficits described, and the corresponding structures involved, which of the following vessels is most likely occluded?
Correct Answer
C. Posterior inferior cerebellar artery
Explanation
The posterior inferior cerebellar artery (commonly called PICA by clinicians) serves the posterolateral portion of the medulla, which encompasses the anterolateral system, spinal trigeminal tract, and nucleus ambiguus. The anterior and medial areas of the medulla (containing the pyramid, medial lemniscus, and hypoglossal nucleus/nerve) are served by the anterior spinal artery and the anterolateral area of the medulla (the region of the olivary nuclei) is served by penetrating branches of the vertebral artery. The posterior spinal artery serves the posterior column nuclei in the medulla and the anterior inferior cerebellar artery (commonly called AICA) serves caudal portions of the pons and cerebellum.(p.104–109,112)
5.
A 77-year-old man presents with an ataxic gait. There are no other deficits. CT shows an infarcted area in the medulla in the territory served by the posterior inferior cerebellar artery. Damage to which of the following structures would most likely explain the symptoms experienced by this man?
Correct Answer
D. Rest form body
Explanation
The restiform body is a large fiber bundle located in the posterolateral area of the medulla in the region served byposterior inferior cerebellar artery (PICA).This structure contains a variety of cerebellar afferent fibers including those of the posterior spinocerebellar tract. Damage to the vestibular nuclei will result in a tendency to fall to the ipsilateral side but will also produce diplopia (double vision) and nausea; symptoms not experienced by this patient. The anterolateral system is sensory, the nucleus ambiguus is motor to muscles of the throat (including the vocalis),and the corticospinal tract is not in the PICA territory.(p.104–109,112)
6.
Which of the following cranial nerve nuclei is located in the anterior (ventral or inferior) and medial portion of the periaqueductal grey at the cross-sectional level of the superior colliculus?
Correct Answer
C. Oculomotor
Explanation
The oculomotor nucleus (containing general somatic efferent [GSE] cell bodies),along with the Edinger-Westphal(containing general visceral efferent [GVE] cell bodies) nucleus, is found in the most anterior and medial portion of the periaqueductal grey at the superior colliculus level. The trochlear nucleus is found at a comparable position, but at the cross-sectional level of the inferior colliculus. The mesencephalic nucleus is found in the lateral area of the periaqueductal grey, and the trigeminal and abducens nuclei are located in the pons.(p.132–133)
7.
A 53-year-old woman presents with motor deficits that the examining neurologist describes as a superior alternating hemiplegia. Which of the following cranial nerve roots is most likely involved in this lesion?
Correct Answer
C. Oculomotor
Explanation
A superior alternating (or alternate) hemiplegia is characterized by a loss of most eye movement (damage to oculomotor nerve fibers) on the ipsilateral side and weakness of the upper and lower extremities (damage to corticospinal fibers in the crus cerebri) on the contralateral side. The abducens nerve is the cranial nerve involved in a middle alternating hemiplegia and the hypoglossal is that nerve involved in an inferior alternating hemiplegia. The trigeminal nerve innervates the muscles of mastication and the trochlear nerve innervates the superior oblique muscle.(p.132–133,138)
8.
An 82-year-old woman presents to the emergency department with difficulty swallowing (dysphagia).Which of the following nuclei of the medulla contain motor neurons that innervate muscles involved in swallowing?
Correct Answer
E. Nucleus ambiguus
Explanation
Motor neurons in the nucleus ambiguus innervate, primarily through the vagus nerve, the muscles of the throat that move a bolus of food from the oral cavity to the esophagus. The tongue, via the hypoglossal nucleus and nerve, may move food around in the mouth and toward the back of the oral cavity, but the actual act of swallowing is through the action of pharyngeal and laryngeal musculature. The dorsal motor vagal and inferior salivatory nuclei are both visceromotor (autonomic) nuclei, and the medial vestibular nucleus is involved in the regulation of eye movement and balance and equilibrium.(p.50,104–107,112)
9.
A 73-year-old man is brought to the emergency department after losing consciousness at his home. CT shows a hemorrhage into the right hemisphere. The man regains consciousness, but is not fully alert. After 3 to 4 days the man begins to rapidly deteriorate. His pupils are large (dilated) and respond slowly to light, eye movement becomes restricted, there is weakness in the extremities on the left side, and the man becomes comatose. Repeat CT shows an uncalherniation.
Based on its location, which of the following parts of the brain-stem is most likely to be directly affected by uncal herniation, especially in the early stages?
Correct Answer
B. MesencepHalon/midbrain
Explanation
The uncus is at the rostral and medial aspect of the parahippocampal gyrus, and, in this position, is directly adjacent to the anterolateral aspect of the midbrain. The diencephalon is rostral to this point and the medulla, the most caudal part of the brainstem, is located in the posterior fossa. Late stages of uncal herniation may, but not always, result in damage to the rostral pons; this is especially so if the patient becomes decerebrate. The cerebellum is not involved in uncal herniation.(p.20,22,24,152–153)
10.
A 73-year-old man is brought to the emergency department after losing consciousness at his home. CT shows a hemorrhage into the right hemisphere. The man regains consciousness, but is not fully alert. After 3 to 4 days the man begins to rapidly deteriorate. His pupils are large (dilated) and respond slowly to light, eye movement becomes restricted, there is weakness in the extremities on the left side, and the man becomes comatose. Repeat CT shows an uncalherniation.
Damage to corticospinal fibers in which of the following locations would most likely explain the weakness in his extremities?
Correct Answer
D. Right crus cerebri
Explanation
Uncal herniation compresses the lateral portion of the brainstem, eventually resulting in compression of the corti-cospinal fibers in the crus cerebri. Weakness on the patient’s left side indicates damage to corticospinal fibers in the right crus. In situations of significant shift of the midbrain due to the herniation, the contralateral crus also may be damaged, resulting in bilateral weakness. Although all other choices contain corticospinal fibers, none of these areas are directly involved inuncal herniation.(p.138)
11.
A 73-year-old man is brought to the emergency department after losing consciousness at his home. CT shows a hemorrhage into the right hemisphere. The man regains consciousness, but is not fully alert. After 3 to 4 days the man begins to rapidly deteriorate. His pupils are large (dilated) and respond slowly to light, eye movement becomes restricted, there is weakness in the extremities on the left side, and the man becomes comatose. Repeat CT shows an uncalherniation.
The dilated, and slowly responsive, pupils in this man are most likely explained by damage to fibers in which of the following?
Correct Answer
C. Oculomotor nerve
Explanation
The root of the oculomotor nerve conveys GSE fibers to four of the six major extra ocular muscles and GVE parasympathetic preganglionic fibers to the ciliary ganglion from which postganglionic fibers travel to the sphincter muscle of the iris. Pressure on the oculomotor root, as in uncal herniation, will usually compress the smaller diameter, and more superficially located GVE fibers first. Optic nerve damage results in blindness in that eye, injury to sympathetic fibers to the eye results in constriction of the pupil, and an abducens root injury results in an inability to abduct that eye. A lesion of corticonuclear fibers in the crus results primarily in motor deficits related to the facial, hypoglossal, and accessory nerves.(p.138)
12.
The sagittal MRI of a 26-year-old man shows a dark shadow in the midbrain tegmentum on the midline at the cross-sectional level of the inferior colliculus. Which of the following structures does this dark area represent?
Correct Answer
C. Decussation of the superior cerebellar peduncle
Explanation
The decussation of the superior cerebellar peduncle is a prominent fiber bundle located in the tegmentum of the midbrain directly on the midline at the level of the inferior colliculus. This bundle is made up of cerebellar efferent fibers. Thered nucleus is located in the midbrain tegmentum, but not on the midline. Decussating trigeminothalamic fibers are found in the medulla and do not form a visible structure on the midline. The motor decussation is a compact bundle on the midline, but it is in the medulla, not the midbrain. The main parts of the substantia nigra are in the midbrain, are seen in sagittal MRI, but they are definitely not on the midline.(p.130–1
13.
The CT of a 39-year-old man with untreated hypertension shows a small hemorrhage in the brainstem. This lesion encompasses the brachium of the inferior colliculus and the brain sub-stance immediately internal to this structure. Which of the following structures is also most likely involved in this lesion?
Correct Answer
A. Anterolateral system
Explanation
The anterolateral system is located just internal to the brachium of the inferior colliculus in the lateral portions of the midbrain tegmentum. This tract conveys pain and thermal sensations from the contralateral side of the body excluding the face. Corticospinal fibers are located in the crus cerebri, the mesencephalic tract at the lateral edge of the periaqueductal(central) grey, and the central tegmental tract is, as its name indicates, in the central part of the tegmentum. Oculomotorfibers within the midbrain leave the nucleus, arch through the tegmentum, and exit on the medial surface of the basis pedunculi into the interpeduncular cistern.(p.130–133)
14.
A 69-year-old man complains of difficulty walking. The examination reveals no weakness, but does reveal a loss of discriminative touch and vibratory sense on the left lower extremity. MRI shows a small infarcted area in the midbrain. Which of the following structures is most likely involved in the infarcted area?
Correct Answer
C. Lateral part of the medial lemniscus
Explanation
Fibers conveying discriminative touch, vibratory sensations, and proprioception are located in the lateral lemniscus; those from the contralateral upper extremity are medial, whereas those from the contralateral lower extremity are lateral. This man has difficulty walking due to a lesion of fibers conveying position sense from the lower extremity, not due to a lesion influencing descending fibers passing to spinal motorneurons. Fibers of the anterolateral system convey pain and thermal sensation. Rubrospinal and corticospinal are motor infunction; however this man has no weakness.(p.130–133)
15.
Which of the following nuclei containing visceromotor (auto-nomic) cell bodies is located immediately inferior to the medial vestibular nucleus, medial to the solitary tract and nucleus, and has axons that exit the brainstem on the glossopharyngeal nerve?
Correct Answer
C. Inferior salivatory nucleus
Explanation
The inferior salivatory nucleus is located in the rostral medulla, medial to the solitary tract and nuclei and inferior to the medial vestibular nucleus. Preganglionic axons that originate from these cells distribute on branches of the glossopharyngeal nerve. The dorsal motor nucleus is in the medulla, its axons travel on the vagus nerve. The superior salivatory nucleus is in the caudal pons and is associated with the facial nerve. Cells of the Edinger-Westphal nucleus are associated with the oculomotor nucleus of the midbrain and the intermediolateral cell column is located primarily in thoracic levels of the spinal cord.(p.104–107)
16.
An 81-year-old woman is brought to the emergency department by her adult grandson. He explains that during dinner she slumped off of her chair, did not lose consciousness, but had trouble speaking. The examination reveals weakness of the upper and lower extremities on the left and deviation of the tongue to the right on protrusion. Which of the following most specifically describes this deficit in this elderly patient?
Correct Answer
C. Inferior alternating hemiplegia
Explanation
Weakness of the extremities accompanied by paralysis of muscles on the contralateral side of the tongue (seen as a deviation of the tongue to that side on protrusion) indicates a lesion in the medulla involving the corticospinal fibers in the pyramid and the exiting hypoglossal roots. This is an inferior alternating hemiplegia. Middle alternating hemiplegia refers to a lesion of the pontine corticospinal fibers and the root of the abducens nerve, and superior alternating hemiplegia specifies damage to the oculomotor root and crus cerebri. Alternating(alternate) hemianesthesia and hemihypesthesia are sensory losses.(p.112)
17.
A 79-year-old woman is brought to the emergency department after a fall in her home from which she was unable to get up. The examination reveals a deviation of the tongue to the left on protrusion, pronounced weakness of the right upper and lower extremities, and a loss of position and vibratory sense and discriminative touch on the right side of the body below the neck. CT shows an infarcted area in the medulla.
Which of the following represents the best localizing sign in this patient?
Correct Answer
A. Deviation of the tongue
Explanation
The deviation of the tongue to the left on attempted protrusion is the best localizing sign in this woman. This is especially the case when the deviation of the tongue is seen in concert with the motor and sensory losses described for this patient. This clearly indicates a lesion in the medial medulla encompassing the corticospinal fibers, medial lemniscus, and exiting fibers on the hypoglossal nerve. Motor and sensory losses, without the cranial nerve sign, could suggest a lesion at several different levels of the neuraxis.(p.112)
18.
A 79-year-old woman is brought to the emergency department after a fall in her home from which she was unable to get up. The examination reveals a deviation of the tongue to the left on protrusion, pronounced weakness of the right upper and lower extremities, and a loss of position and vibratory sense and discriminative touch on the right side of the body below the neck. CT shows an infarcted area in the medulla.
Damage to which of the following tracts or fiber bundles would most likely give rise to the sensory deficits experienced by this patient?
Correct Answer
B. Medial lemniscus
Explanation
All of the sensory deficits seen in this woman reflecta lesion in the medial lemniscus, which is located in the medial medulla in the territory of the anterior spinal artery. The anterolateral system and the spinal trigeminal tract convey pain and thermal sensations from the body (sans face) and face, respectively. The solitary tract is made up of the central processes of viscerosensory fibers and the medial longitudinal fasciculus at this level contains descending fibers that influence spinal motor neurons.(p.106–109,112)
19.
The MRI of a 12-year-old boy reveals a cavity within the medulla. Which of the following terms most specifically describes this condition?
Correct Answer
D. Syringobulbia
Explanation
Syringobulbia is a cavitation within the medulla. Cavitation in this location may communicate with a cavity in cervical levels of the spinal cord (syringomyelia).Hydromyelia refers to a cavity of the spinal cord that is lined with ependymal cells. The central cord and Brown-Séquard syndromes are lesions of the spinal cord that give rise to characteristic motor and sensory losses.(p.112)
20.
Which of the following cell groups within the white matter of the cerebellum characteristically appears as a long undulating line, looking somewhat like the principal olivary nucleus in the medulla?
Correct Answer
A. Dentate nucleus
Explanation
The dentate nucleus appears as a long thin undulating line within the white matter core of the cerebellar hemi-sphere. It is frequently described as having the three-dimensional shape of a crumpled bag with its hilus (the opening of the bag) directed rostromedially. The other cerebellar nuclei(fastigial, globose, emboli form) are small clumps of cells, and the red nucleus is found in the midbrain, not in the cerebellum.(p.114–115)