Pathophysiology Ch 51 Review

Microneurons are small cells that are intimately involved in local circuitry. These cells play a crucial role in the functioning of the nervous system, particularly in the transmission of signals within specific regions of the brain. The term "microneurons" suggests that these cells are smaller in size compared to macroneurons, which are larger neurons involved in long-range communication. Therefore, the presence or involvement of microneurons can have significant implications for the local circuitry and functioning of specific brain regions.

Aphasia refers to the inability to comprehend, integrate, and express language. This condition can result from various causes such as brain damage, stroke, or neurological disorders. It affects a person's ability to understand and use words, sentences, and gestures. Individuals with aphasia may struggle to find the right words, have difficulty understanding spoken or written language, and may have trouble forming coherent sentences. It can significantly impact communication and may require speech therapy or other interventions to improve language skills.

Macroneurons are large cells with long axons that send action potentials to other regions of the nervous system. This explanation aligns with the given description of macroneurons as large cells with long axons that leave the local network of intercommunicating neurons to send action potentials to other regions of the nervous system.

Excitotoxicity refers to the damage caused to neurons by excessive activity of excitatory neurotransmitters, such as glutamate, and their receptor-mediated effects. This can occur in various neurological conditions, including hypoxic-ischemic injury, where there is a lack of oxygen and blood supply to the brain. The excessive release of excitatory neurotransmitters during hypoxic-ischemic events can lead to excitotoxicity and subsequent neuronal damage. Therefore, excitotoxicity is a plausible explanation for the given answer.

Hypoxic refers to a condition where there is a decrease in oxygen levels in all brain tissue. This can occur due to various reasons such as reduced blood flow or inadequate oxygen supply. When the brain does not receive enough oxygen, it can lead to damage and dysfunction of the brain cells. Therefore, hypoxic is the correct answer as it accurately describes the decreased oxygen levels in all brain tissue.

The tentorium cerebelli is a structure in the brain that separates the cranial cavity into anterior and posterior fossae. It is a thick, crescent-shaped fold of dura mater that lies horizontally between the cerebrum and the cerebellum. Its main function is to provide structural support and prevent downward displacement of the cerebrum under the weight of the cerebellum. Therefore, the correct answer is tentorium cerebelli.

Hydrocephalus refers to an abnormal increase in cerebrospinal fluid (CSF) volume in any part or all of the ventricular system. This condition can occur due to various reasons such as obstruction of CSF flow, overproduction of CSF, or impaired absorption of CSF. The increased CSF volume can lead to increased pressure within the brain, causing symptoms such as headaches, nausea, and cognitive impairments. Treatment for hydrocephalus often involves the insertion of a shunt to redirect the excess CSF to another part of the body where it can be absorbed.

Altered level of consciousness is almost always a manifestation of a global brain injury. This is because a global brain injury affects the entire brain, leading to widespread dysfunction and impairment of consciousness. It can result in a range of consciousness alterations, such as confusion, disorientation, lethargy, or even coma. On the other hand, focal brain injuries typically affect specific regions of the brain, leading to localized symptoms and deficits, rather than a generalized alteration of consciousness. Therefore, altered level of consciousness is a reliable indicator of a global brain injury.

Generalized convulsive status epilepticus is a medical emergency characterized by continuous or repetitive tonic-clonic seizures. The first-line drug of choice to treat status epilepticus is IV diazepam. Diazepam is a benzodiazepine that acts as an anticonvulsant by enhancing the inhibitory effects of gamma-aminobutyric acid (GABA) in the brain. It is administered intravenously to rapidly terminate the seizure activity and prevent further seizures. Diazepam has a rapid onset of action and a relatively long duration, making it an effective choice for the treatment of status epilepticus. IM lorazepam, IV cyclobenzaprine, and IM cyproheptadine are not the first-line drugs for status epilepticus.

Cerebral edema refers to the swelling of the brain due to an accumulation of fluid. It can occur as a result of various conditions such as hypoxic-ischemic injury, excitotoxicity, increased intracranial volume and pressure, brain herniation, or hydrocephalus. The accumulation of fluid causes the brain tissue to expand, leading to increased pressure within the skull. This can result in various symptoms and complications, including neurological deficits and potentially life-threatening conditions.

Brudzinski sign and Kernig sign are both assessment techniques used to determine the presence of meningeal irritation in suspected cases of bacterial meningitis. Brudzinski sign is positive when flexion of the neck causes involuntary flexion of the hips and knees, indicating irritation of the meninges. Kernig sign is positive when the patient experiences resistance and pain in the hamstring muscles when attempting to extend the leg with the hip flexed at 90 degrees, also indicating meningeal irritation. Therefore, the correct answer is brudzinski sign and kernig sign.

The term "unprovoked" refers to seizures that occur without any clear trigger or identifiable cause. It means that the seizure activity happens spontaneously, without any external factors or stimuli leading to it. This term is often used to describe seizures that are not linked to a specific event or situation, and the exact cause cannot be determined.

Brain herniation refers to the displacement of brain tissue under the falx cerebri or through the tentorial notch or incisura of the tentorium cerebelli. This can occur due to various factors such as hypoxia, ischemia, excitotoxicity, increased intracranial volume and pressure, cerebral edema, or hydrocephalus. Brain herniation is a serious condition that can lead to compression of vital structures in the brain, compromising their function and potentially causing severe neurological deficits or even death. Therefore, brain herniation is the most appropriate explanation for the given scenario.

Hypoxia refers to a condition where there is a deprivation of oxygen in the body despite maintained blood flow. This means that even though blood is still flowing, there is a lack of oxygen reaching the tissues and organs. Hypoxia can lead to various complications and symptoms, such as vasogenic edema (swelling of the brain due to increased permeability of blood vessels), ischemia (insufficient blood supply to tissues), and aphasia (difficulty in understanding or expressing speech). Therefore, hypoxia is the most fitting answer among the given options.

Ischemia refers to the inadequate blood supply to a particular organ or tissue, resulting in reduced or interrupted blood flow. This can lead to a decrease in oxygen and nutrient supply to the affected area, causing cellular damage and dysfunction. Ischemia can occur due to various factors, such as blockage of blood vessels, thrombosis, or vasoconstriction. It is a common cause of conditions like heart attacks and strokes. In the given list of terms, ischemia is the only one that directly relates to reduced or interrupted blood flow, making it the correct answer.

Decorticate posturing refers to a specific abnormal posture characterized by flexion of the arms, wrists, and fingers, along with adduction of the upper extremities, internal rotation, and plantar flexion of the lower extremities. This posture is typically seen in patients with damage to the cerebral hemispheres, particularly in the corticospinal tract. It is a result of the disruption of inhibitory signals from the cortex to the brainstem, leading to unopposed excitatory signals and abnormal muscle tone. Therefore, the patient's presentation described in the question is consistent with decorticate posturing.

Vasogenic edema refers to the swelling of brain tissue due to the disruption of the blood-brain barrier. The blood-brain barrier normally prevents certain substances from entering the brain, but when it is compromised, fluid and proteins can leak into the brain tissue, causing edema. This can occur in conditions such as brain tumors, infections, and inflammation. Vasogenic edema can lead to increased pressure in the brain, resulting in symptoms such as headache, confusion, and neurological deficits. Treatment typically involves addressing the underlying cause and managing the swelling to prevent further damage to the brain.

Tonic-clonic seizures, also known as grand mal seizures, are the most common major motor seizures. They are characterized by a loss of consciousness, stiffening of the body (tonic phase), followed by rhythmic jerking movements (clonic phase). These seizures typically have a generalized onset, meaning they involve both sides of the brain. Unlike complex partial seizures, which may be triggered by specific stimuli or situations, tonic-clonic seizures are unprovoked and can occur without any apparent cause. They can also cause the person to lose control of their muscles and may result in falling or collapsing (atonic).

In the most common surgery for seizure disorders, the amygdala is removed. The amygdala is a small, almond-shaped structure in the brain that is involved in emotions and memory. Removing the amygdala can help reduce or eliminate seizures in patients who do not respond to anticonvulsant medications. This surgery is often performed when the seizures originate from the temporal lobe, which is where the amygdala is located. By removing the amygdala, the abnormal electrical activity that causes seizures can be stopped or significantly reduced.

Hemineglect refers to a neurological condition where an individual is unable to attend to or react to stimuli coming from one side of their body or the environment. This condition typically occurs as a result of damage to the brain's parietal lobe, often on the right side. The affected individual may neglect objects, people, or events that occur on the opposite side of their body or field of vision. This can lead to difficulties with daily activities and a lack of awareness of their own body or surroundings on one side.

Hydrocephalus refers to an abnormal increase in cerebrospinal fluid volume in any part or all of the ventricular system. This condition can result in increased intracranial volume and pressure, leading to symptoms such as brain herniation, cerebral edema, and potentially hypoxic, ischemic, or excitotoxic damage to the brain. Therefore, hydrocephalus is the correct answer as it encompasses the explanation of the given statement.

The given answer, "generalized onset," is the correct answer because the description provided in the question suggests that the clinical signs, symptoms, and EEG changes indicate involvement of both hemispheres at the onset of the seizures. This indicates that the seizures are not localized to a specific area of the brain but instead involve the entire brain, which is characteristic of generalized onset seizures.

In the clinical examination for brain death, the blink reflex, responsiveness, and respiratory effort are assessed to determine if there is any brain function. However, electrocardiographic (ECG) findings are not assessed in this examination. ECG findings are used to assess the electrical activity of the heart and are not directly related to the function of the brain. Therefore, they are not considered in the clinical examination for brain death.

When the blood pressure drops below 60 mm Hg, cerebral blood flow becomes severely compromised. This means that the brain is not receiving enough blood supply to meet its metabolic needs.

Complex partial seizures are a type of seizure that originates in a localized area of the brain. They are characterized by altered consciousness and may involve involuntary movements or behaviors. In some cases, these seizures can progress rapidly to involve both hemispheres of the brain. Unlike absence seizures, which are brief episodes of staring and loss of awareness, complex partial seizures are longer-lasting and can cause a wide range of symptoms. They are also different from atonic seizures, which cause sudden loss of muscle tone, and tonic-clonic seizures, which involve both tonic (rigid) and clonic (jerking) phases.

Atonic seizures, also known as drop attacks, are a type of seizure characterized by a sudden loss of muscle tone, causing the person to collapse or fall. These seizures are unprovoked, meaning they occur without any specific trigger. They are considered a type of generalized onset seizure, which means they involve the whole brain from the beginning. Atonic seizures are different from tonic-clonic seizures, which involve both muscle stiffness and jerking movements, and absence seizures, which cause a brief loss of awareness.

Brain tumors can cause focal disturbances in brain function due to brain edema and disturbances in blood flow. Brain edema refers to the swelling of the brain tissue caused by the accumulation of fluid. This swelling can lead to compression of surrounding brain structures, resulting in focal disturbances. Additionally, brain tumors can disrupt the normal blood flow in the brain, causing further impairment in brain function. Therefore, brain edema and disturbances in blood flow are the likely causes of the focal disturbances manifested by brain tumors.

Ischemic refers to a condition where there is a decreased blood supply to a particular organ or tissue. In the context of the given statement, ischemic would refer to a decreased blood supply to the brain. This lack of blood supply interferes with the delivery of oxygen and glucose, which are essential for the brain's normal functioning. It also hinders the removal of metabolic wastes, leading to a buildup of toxins. Therefore, ischemic can explain how the mentioned condition interferes with the delivery of oxygen and glucose as well as the removal of metabolic wastes.

An increase in intracranial volume and pressure can lead to various conditions such as brain herniation, cerebral edema, and hydrocephalus. These conditions occur when there is an excessive amount of fluid or tissue within the skull, causing compression and damage to the brain. This can result in a decrease in blood flow and oxygen supply to the brain, leading to hypoxia and ischemia. Additionally, the increased pressure can also cause excitotoxicity, which is the damage to brain cells due to excessive stimulation. Therefore, the increase in intracranial volume and pressure can lead to a range of complications and impair brain function.

Cerebral edema refers to the swelling of the brain due to an accumulation of fluid. The extent of cerebral edema depends on the brain's compensatory mechanisms, which are its ability to adapt and respond to the swelling, and the extent of the swelling itself. Cerebral edema can occur as a result of various conditions such as hypoxic-ischemic injury, excitotoxicity, increased intracranial volume and pressure, brain herniation, or hydrocephalus. The correct answer, cerebral edema, is chosen because it best fits the given explanation.

The given description of motion in the form of automatisms such as lip smacking, mild clonic motion, increased or decreased postural tone, and autonomic phenomena suggests the presence of absence seizures. Absence seizures are a type of generalized onset seizure characterized by a sudden brief loss of awareness, often accompanied by subtle motor movements. These seizures typically last for a few seconds and the person may appear to be staring blankly. The description matches the symptoms of absence seizures, making it the correct answer.

The diagnosis of intracranial aneurysms and subarachnoid hemorrhage is made through a lumbar puncture. This procedure involves inserting a needle into the lower back to collect a sample of cerebrospinal fluid (CSF) for analysis. In the case of a subarachnoid hemorrhage, the CSF may appear bloody due to the presence of blood in the subarachnoid space. This can confirm the presence of a ruptured aneurysm and help guide further treatment decisions. Magnetic resonance imaging (MRI) can also be used to visualize the aneurysm, but a lumbar puncture is necessary for definitive diagnosis. Loss of cranial nerve reflexes and venography are not typically used for the diagnosis of intracranial aneurysms and subarachnoid hemorrhage.

Hydrocephalus is a condition characterized by the accumulation of excess cerebrospinal fluid (CSF) in the brain, leading to enlargement of the cerebral ventricles. This excess fluid causes the cerebral hemispheres to become enlarged and the ventricular system beyond the point of obstruction to become dilated. As a result, the sulci on the surface of the brain become effaced and shallow, and the volume of white matter is reduced. Therefore, hydrocephalus is the most suitable explanation for the given description.

Ischemic refers to a condition where there is inadequate blood flow to a part of the brain, resulting in reduced oxygen and nutrient supply. This can lead to cell death and tissue damage. The given statement suggests that ischemic events can be focal, affecting only one part of the brain, or global, affecting the entire brain. This explanation aligns with the definition of ischemic and the options provided in the question.

Hypoxia refers to a condition in which there is a lack of oxygen supply to the brain. When the brain is deprived of oxygen, it can lead to a generalized depressant effect on the brain. This means that the brain's normal functioning is impaired, resulting in decreased activity and function. This can manifest as symptoms such as confusion, dizziness, and loss of consciousness. Therefore, the correct answer, hypoxic, suggests that the condition of hypoxia can cause a generalized depressant effect on the brain.

The primary (or direct) brain injuries include focal lesions of laceration, contusion, diffuse axonal, and hemorrhage. These types of injuries directly affect the brain and can lead to various symptoms and complications. Focal lesions of laceration occur when there is a tear or cut in a specific area of the brain. Contusion refers to a bruise on the brain tissue caused by a blow or impact. Diffuse axonal injury happens when the brain moves rapidly back and forth, causing damage to the nerve fibers. Hemorrhage refers to bleeding in the brain, which can be caused by a ruptured blood vessel.

Excitotoxicity refers to the process of neuronal cell injury and death caused by excessive stimulation of glutamate receptors. Glutamate is an excitatory neurotransmitter in the brain, and an excessive release of glutamate can lead to an overload of calcium ions in the neurons, triggering a cascade of events that ultimately result in cell death. Excitotoxicity can occur in various conditions such as stroke, traumatic brain injury, and neurodegenerative diseases. It is characterized by the overactivation of glutamate receptors and subsequent damage to neuronal cells.

Decorticate posturing refers to a specific abnormal posture often seen in patients with damage to the cerebral hemisphere. It is characterized by flexion of the arms and clenched fists, with the legs extended and internally rotated. This posture indicates dysfunction in the corticospinal tracts, which are responsible for voluntary movement. Lesions in the cerebral hemisphere can disrupt these tracts, leading to decorticate posturing. This abnormal posture is a result of the loss of inhibitory control from higher brain centers, causing exaggerated flexor muscle tone.

The given symptoms of clouding of consciousness, bilaterally small pupils, purposeful or semipurposeful motor responses to pain, and often asymmetric responses suggest a brain herniation. Brain herniation occurs when there is increased intracranial pressure that causes the brain to shift from its normal position, leading to compression of vital structures. This can result in altered consciousness, abnormal pupil size, and motor responses. Other options like hypoxic, ischemic, excitotoxic, increased intracranial volume and pressure, cerebral edema, and hydrocephalus may also cause similar symptoms, but brain herniation is the most likely explanation based on the given information.

The criteria for the diagnosis of persistent vegetative state include bowel and bladder incontinence, lack of language comprehension, and variable preserved cranial nerve reflexes. These criteria must have lasted for more than 1 month.

When tissue perfusion becomes inadequate, it means that the blood flow to the tissues is not sufficient to meet their oxygen and nutrient demands. As a result, cellular hypoxia occurs, which is a condition where the cells do not receive enough oxygen. This can lead to neuronal death, as the brain cells are highly sensitive to oxygen deprivation. Increased intracranial volume and pressure refers to a condition where there is an abnormal accumulation of fluid or mass within the skull, causing the pressure inside the skull to rise. This can compress the brain tissue and impede blood flow, further exacerbating tissue perfusion and leading to cellular hypoxia and neuronal death.