Neuropathology Practice Questions

Q: What is the primary pathological mechanism in classical Guillain-Barré syndrome affecting the peripheral nervous system?

It causes demyelination of peripheral nerves.. ***It causes demyelination of peripheral nerves.*** - Classical Guillain-Barré syndrome (AIDP - Acute Inflammatory Demyelinating Polyneuropathy) is an autoimmune disorder where the immune system attacks the **myelin sheath** surrounding peripheral nerves. - This **demyelination** impairs nerve signal conduction, leading to weakness and paralysis. - AIDP represents the most common form of GBS in Western countries (~85-90% of cases). *It blocks neurotransmitter release.* - Conditions like **Lambert-Eaton myasthenic syndrome** primarily involve antibodies targeting presynaptic voltage-gated calcium channels, thereby reducing neurotransmitter release. - While GBS affects nerve conduction, its primary mechanism is not the blockage of neurotransmitter release at the synapse. *It inhibits muscle contraction.* - Inhibition of muscle contraction is a downstream effect of impaired nerve innervation, but the fundamental problem in GBS is with the **nerve itself**, not the muscle's ability to contract directly. - Conditions like **myasthenia gravis** directly affect neuromuscular transmission by blocking acetylcholine receptors on muscle fibers. *It leads to axonal degeneration.* - While **axonal variants** of GBS exist (AMAN - Acute Motor Axonal Neuropathy; AMSAN - Acute Motor-Sensory Axonal Neuropathy), particularly common in Asia, the **classical and most common form** is characterized by **primary demyelination** (AIDP). - Pure axonal degeneration as a primary pathology is seen in specific GBS variants, not the classical presentation. - Secondary axonal damage can occur in severe or prolonged cases.

Q: Which neurotransmitter is primarily involved in the pathophysiology of Alzheimer's disease?

Acetylcholine. ***Acetylcholine*** - **Acetylcholine** is the primary neurotransmitter significantly impacted in Alzheimer's disease, with a marked **loss of cholinergic neurons** in the basal forebrain. [2] - This **cholinergic deficit** is associated with impaired memory, learning, and cognitive function, which are core symptoms of the disease. [1] *Dopamine* - **Dopamine** is mainly involved in motor control, reward, and motivation, and its dysregulation is central to diseases like **Parkinson's disease** and schizophrenia. - While dopamine pathways can be indirectly affected in later stages of Alzheimer's, it is not considered the primary neurotransmitter involved in its pathophysiology. *Serotonin* - **Serotonin** plays a crucial role in mood, sleep, appetite, and emotional regulation, and its imbalances are implicated in **depression** and anxiety disorders. - Although serotonin-producing neurons can be affected in Alzheimer's, it is not the main neurotransmitter driving the cognitive decline. [2] *GABA* - **GABA (gamma-aminobutyric acid)** is the major inhibitory neurotransmitter in the brain, essential for reducing neuronal excitability and maintaining neuronal stability. - While GABAergic system changes can occur in Alzheimer's, related to neuronal loss and plasticity, it is not considered the primary neurotransmitter whose deficit directly underpins the cognitive symptoms.

Q: In which type of cells are Negri bodies, characteristic of rabies virus infection, most commonly found?

Neurons. ***Neurons*** - **Negri bodies** are eosinophilic, sharply demarcated **intracytoplasmic inclusions** found in the cytoplasm of neurons, particularly in the **hippocampus** (Ammon's horn) and **Purkinje cells** of the cerebellum [1]. - Their presence is **pathognomonic** for **rabies virus infection**, indicating viral replication within these nerve cells [1]. *Hepatocytes* - Hepatocytes are liver cells and are not the primary site for rabies virus replication or the formation of Negri bodies. - While some viruses infect hepatocytes, rabies primarily targets the **central nervous system**. *Epithelial cells* - Epithelial cells form linings and coverings throughout the body, but they are not the primary host cells for rabies virus replication. - Rabies virus directly impacts the **nervous system**, not epithelial tissues. *Cardiomyocytes* - Cardiomyocytes are muscle cells of the heart and are not typically infected by the rabies virus. - Rabies is a **neurotropic virus**, meaning it specifically targets neuronal tissue. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1279-1280.

Q: Which of the following is a pathological characteristic of Alzheimer's disease?

Plaques and tangles. ***Plaques and tangles*** - The hallmark pathological features of **Alzheimer's disease** are extracellular **amyloid-beta plaques** and intracellular neurofibrillary tangles composed of hyperphosphorylated tau protein [1], [2]. - These accumulations lead to neuronal dysfunction and death, causing the characteristic symptoms of the disease [1]. *Increased reflexes* - **Increased reflexes** (hyperreflexia) are not a characteristic pathological feature of Alzheimer's disease; they are more commonly seen in conditions affecting upper motor neurons, such as **stroke** or **multiple sclerosis**. - Alzheimer's primarily affects cognitive function and does not typically present with significant motor system abnormalities in its early stages. *Gradual cognitive decline* - **Gradual cognitive decline** is a *clinical symptom* of Alzheimer's disease, not a pathological characteristic [1]. - It describes the functional manifestation of the underlying neuropathology rather than the specific tissue changes. *Subcortical atrophy* - Alzheimer's disease predominantly causes **cortical atrophy**, particularly affecting the hippocampus, temporal lobes, and parietal lobes, rather than primarily subcortical structures [2]. - While brain atrophy occurs, the most characteristic and specific pathological changes at the microscopic level are the **plaques and tangles**, which are the definitive diagnostic features on histopathology [1], [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1292-1294. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 720-722.

Q: A 70-year-old male presents with progressive memory loss, visual hallucinations, and parkinsonism. Which neuropathological finding is most characteristic of his condition?

Lewy Bodies. ***Lewy Bodies*** [1] - The presence of **visual hallucinations**, **memory loss**, and **parkinsonism** points towards Lewy body dementia, which is characterized by the presence of these abnormal aggregates [1]. - **Lewy bodies** contain the protein **alpha-synuclein**, which is linked to the pathophysiology of both Parkinson's disease and dementia with Lewy bodies [1][2]. *Neurofibrillary Tangles* - Typically associated with **Alzheimer's disease**, they represent **tau protein** abnormalities rather than the symptoms presented. - Do not account for the **visual hallucinations** or the combination of symptoms seen in this patient. *Pick Bodies* - Associated with **Frontotemporal lobar degeneration**, these are not related to the **parkinsonian features** or hallucinations described. - Characterized by changes in personality and social behavior, which differ from the clinical picture here. *Amyloid Plaques* - Primarily found in **Alzheimer's disease**, which does not typically present with visual hallucinations or parkinsonism. - Amyloid plaques are related to cognitive impairment, but not the combination of symptoms in this case. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1297-1298. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1296-1297.

Q: A 60-year-old man presents with memory loss, difficulty performing daily activities, and visuospatial disorientation. Which protein accumulation is characteristic of the most likely diagnosis?

Beta-amyloid. ***Beta-amyloid*** - The symptoms of memory loss, difficulty performing daily activities, and visuospatial disorientation are highly suggestive of **Alzheimer's disease**. [1] - **Beta-amyloid plaques** (extracellular) and **neurofibrillary tangles** (intracellular tau) are the two hallmark pathological features of Alzheimer's disease. [1], [2] - Beta-amyloid accumulation is considered the most **characteristic** finding, as it is relatively specific to Alzheimer's disease, whereas tau pathology can occur in various neurodegenerative conditions. [1] *Tau protein* - While **hyperphosphorylated tau protein** forms **neurofibrillary tangles**, which are equally important in Alzheimer's disease pathology, tau accumulation is **less specific** as it occurs in multiple tauopathies. [1] - Other tauopathies include frontotemporal dementia, progressive supranuclear palsy, and corticobasal degeneration, which present with different clinical profiles. - Both amyloid and tau pathology contribute to neurodegeneration in Alzheimer's disease. *Alpha-synuclein protein* - Accumulation of **alpha-synuclein protein** is characteristic of **Parkinson's disease** and **Lewy body dementia** (LBD). [2] - LBD commonly involves fluctuating cognition, visual hallucinations, and Parkinsonism, which differ from the typical Alzheimer's presentation. *Prion proteins* - **Prion diseases** (e.g., Creutzfeldt-Jakob disease) are characterized by misfolded **prion proteins**, leading to rapidly progressive dementia. - The clinical presentation typically involves a much more rapid decline (weeks to months) and additional neurological signs such as myoclonus and ataxia. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1290-1294. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 719-722.

Q: Negri bodies are characteristic of which disease?

Rabies. ***Correct: Rabies*** - **Negri bodies** are eosinophilic, sharply outlined cytoplasmic inclusions found in the **pyramidal cells of the hippocampus** and the **Purkinje cells of the cerebellum** of individuals infected with rabies [1]. - Their presence is considered **pathognomonic** for rabies infection and can be detected post-mortem during diagnosis [1]. - These are characteristic intracytoplasmic viral inclusions that are diagnostic of rabies encephalitis. *Incorrect: Tetanus* - Tetanus is caused by the bacterium *Clostridium tetani*, which produces a neurotoxin (tetanospasmin) leading to muscle spasms and rigidity. - It does not involve the formation of distinctive microscopic inclusions like Negri bodies. - Diagnosis is primarily clinical based on characteristic muscle spasms. *Incorrect: Polio* - Polio is a viral disease caused by poliovirus, primarily affecting the anterior horn cells of the spinal cord, leading to muscle weakness and paralysis. - While it causes neural damage, it is not associated with the formation of Negri bodies. - Histologically, poliomyelitis shows neuronal degeneration and inflammation but no specific inclusion bodies. *Incorrect: AIDS* - AIDS (Acquired Immunodeficiency Syndrome) is caused by the Human Immunodeficiency Virus (HIV), which attacks the immune system. - While HIV can affect the central nervous system leading to HIV encephalopathy and various opportunistic infections, it does not produce Negri bodies. - CNS manifestations in AIDS include multinucleated giant cells and microglial nodules, not Negri bodies. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1279-1280.

Question 1

What is the primary pathological mechanism in classical Guillain-Barré syndrome affecting the peripheral nervous system?

Accepted Answer

It causes demyelination of peripheral nerves.

Answer

It blocks neurotransmitter release.

Answer

It inhibits muscle contraction.

Answer

It leads to axonal degeneration.

Question 2

Which neurotransmitter is primarily involved in the pathophysiology of Alzheimer's disease?

Accepted Answer

Acetylcholine

Answer

Dopamine

Answer

Serotonin

Answer

GABA

Question 3

In which type of cells are Negri bodies, characteristic of rabies virus infection, most commonly found?

Accepted Answer

Neurons

Answer

Hepatocytes

Answer

Epithelial cells

Answer

Cardiomyocytes

Question 4

Which of the following is a pathological characteristic of Alzheimer's disease?

Accepted Answer

Plaques and tangles

Answer

Gradual cognitive decline

Answer

Increased reflexes

Answer

Subcortical atrophy

Question 5

A 70-year-old male presents with progressive memory loss, visual hallucinations, and parkinsonism. Which neuropathological finding is most characteristic of his condition?

Accepted Answer

Lewy Bodies

Answer

Neurofibrillary Tangles

Answer

Amyloid Plaques

Answer

Pick Bodies

Question 6

A 60-year-old man presents with memory loss, difficulty performing daily activities, and visuospatial disorientation. Which protein accumulation is characteristic of the most likely diagnosis?

Accepted Answer

Beta-amyloid

Answer

Tau protein

Answer

Alpha-synuclein protein

Answer

Prion proteins

Question 7

Which of the following best describes the pathophysiology of migraine?

Accepted Answer

Migraines involve vasodilation and neurogenic inflammation.

Answer

Migraines result from purely vascular constriction without neurogenic involvement.

Answer

Migraines are caused by cortical spreading depression alone without vascular changes.

Answer

Migraines are caused by primary vasoconstriction leading to cerebral ischemia.

Question 8

A 35-year-old male presents with severe headache, confusion, high blood pressure, and brain hemorrhage. Given his history of chronic hypertension, which specific vascular mechanism is most likely responsible for his condition?

Accepted Answer

Rupture of small penetrating arteries due to chronic hypertension leading to intracerebral hemorrhage

Answer

Decreased cerebral blood flow due to ischemic stroke

Answer

Compression of brain structures by an arterial aneurysm

Answer

Increased intracranial pressure due to venous thrombosis

Question 9

Which of the following statements is MOST accurate regarding Huntington's disease?

Accepted Answer

It is caused by an increased number of CAG repeats in the HTT gene.

Answer

There is a loss of function type of mutation

Answer

It is an autosomal recessive

Answer

It is a trinucleotide repeat expansion type of disorder

Question 10

Negri bodies are characteristic of which disease?

Accepted Answer

Rabies

Answer

Tetanus

Answer

Polio

Answer

AIDS

Neuropathology — MCQs

Neuropathology — MCQs

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