Neuropathology — MCQs

Neuropathology Indian Medical PG Practice Questions and MCQs

Question 341: What is the first cellular response observed after a sharp nerve cut?

A. Chromatolysis (Correct Answer)
B. Polymorphic arrangement
C. Increased protein synthesis
D. Macrophage activation

Explanation: ***Chromatolysis*** - **Chromatolysis** is the dissolution of the Nissl bodies (rough endoplasmic reticulum) in the neuron cell body following axonal injury, which is the **first observable cellular response** [1]. - This process is a preparatory step for neuronal regeneration, indicating the cell's attempt to repair the damaged axon [1]. *Polymorphic arrangement* - This term is not typically used to describe an immediate cellular response to a nerve cut; it might refer to diverse cell shapes or arrangements in different contexts but is not a recognized initial post-injury event. - The neuron's immediate response involves changes within the cell body, not a re-arrangement of its cellular structure with other cells. *Increased protein synthesis* - While increased protein synthesis does occur during neuronal repair and regeneration, it is a consequence of chromatolysis and part of a later, more sustained response, not the very first visible cellular change [1]. - **Chromatolysis precedes** and facilitates the subsequent increase in protein synthesis necessary for axonal regrowth [1]. *Macrophage activation* - **Macrophage activation** is a crucial part of the inflammatory response and debris clearance following nerve injury, but it is not the *first cellular response* of the neuron itself [2]. - Macrophages migrate to the site of injury hours to days after the initial insult, whereas chromatolysis begins within the neuron's cell body much earlier [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1254-1256. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 697-698.

Question 342: What is the primary process involved in Wallerian degeneration?

A. Nerve degeneration (Correct Answer)
B. Muscle degeneration
C. Nerve regeneration
D. Muscle regeneration

Explanation: ***Nerve degeneration*** - **Wallerian degeneration** specifically refers to the process of **axon degeneration** that occurs distal to the site of injury when a nerve fiber is severed [2]. - This process involves the breakdown of the **axon** and its myelin sheath, leading to loss of function [1]. *Muscle degeneration* - While prolonged nerve degeneration can lead to muscle **atrophy** due to denervation, **muscle degeneration itself** is not the primary process of Wallerian degeneration. - Wallerian degeneration focuses on the **nerve itself**, not the target tissue. *Nerve regeneration* - **Nerve regeneration** is the process where damaged nerves attempt to regrow and re-establish connections [2]. - This is a subsequent, and not always successful, event that can occur *after* Wallerian degeneration has cleared the debris [1]. *Muscle regeneration* - **Muscle regeneration** refers to the repair and regrowth of damaged muscle tissue, typically involving satellite cells. - It is unrelated to Wallerian degeneration, which is a process affecting the **nerve**. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 697-698. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 109-110.

Question 343: What is the characteristic feature of neuropraxia?

A. Damage to the endoneurium
B. Damage to the epineurium
C. No structural damage to the nerve (Correct Answer)
D. Damage to the axon

Explanation: ***No structural damage to the nerve*** - **Neuropraxia** is the mildest form of nerve injury, characterized by a **temporary block in nerve conduction** without structural damage to the axon or surrounding connective tissues. - This typically results in **temporary sensory and/or motor deficits** that fully resolve within weeks to months. *Damage to the endoneurium* - Damage to the **endoneurium** would indicate a more severe injury, such as **axonotmesis**, where the axon is damaged but the connective tissue sheaths are preserved. - This level of injury suggests that wallerian degeneration would occur distal to the lesion, leading to **slower and incomplete recovery**. *Damage to the epineurium* - Damage to the **epineurium**, along with the endoneurium and perineurium, signifies **neurotmesis**, the most severe nerve injury. - This involves a **complete transection of the nerve**, requiring surgical intervention for any chance of functional recovery. *Damage to the axon* - Damage to the **axon** itself, often alongside preserved connective tissues, is characteristic of **axonotmesis**. - While recovery is possible through axonal regeneration, it is **slower and less complete** than in neuropraxia.

Question 344: Which of the following statements about peripheral nerve injury is false?

A. Wallerian degeneration starts in axonotmesis
B. Neuropraxia is irreversible (Correct Answer)
C. Neurotmesis is the most severe form of injury
D. Epineurium is intact in axonotmesis

Explanation: This question asks which statement is **FALSE** about peripheral nerve injury. ***Neuropraxia is irreversible*** - This statement is **FALSE** (making it the correct answer to this question). - Neuropraxia represents the **mildest form** of peripheral nerve injury, characterized by local **demyelination** or temporary conduction block without axonal damage [2]. - Recovery from neuropraxia is typically **complete and rapid**, usually within **weeks to months**, as axonal continuity is preserved. - **No Wallerian degeneration** occurs because the axon remains intact. *Epineurium is intact in axonotmesis* - This statement is **TRUE**. In **axonotmesis**, there is disruption of the axon and myelin sheath, but the **connective tissue sheaths** (epineurium, perineurium, and endoneurium) remain intact. - The intact connective tissue provides a guide for **axonal regeneration**, which makes recovery possible, although often incomplete [1]. - Recovery occurs at approximately **1 mm/day** or **1 inch/month**. *Neurotmesis is the most severe form of injury* - This statement is **TRUE**. **Neurotmesis** involves complete severance of the nerve fiber, including the axon, myelin, and **all supporting connective tissue structures** (epineurium, perineurium, and endoneurium). - This type of injury has the **poorest prognosis** for recovery and usually requires **surgical intervention** to attempt repair [1]. *Wallerian degeneration starts in axonotmesis* - This statement is **TRUE**. **Wallerian degeneration** is a process that occurs when a nerve fiber is severed or severely injured, affecting the segment **distal to the injury** [1]. - In **axonotmesis**, the axon is disrupted, leading to degeneration of the distal axonal segment and its myelin sheath, which is characteristic of Wallerian degeneration. - Wallerian degeneration also occurs in **neurotmesis** but NOT in **neuropraxia**. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 109-110. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, p. 1232.

Question 345: Homer-Wright rosette is seen in -

A. Nephroblastoma
B. Hepatoma
C. Ependymoma
D. Neuroblastoma (Correct Answer)

Explanation: ***Neuroblastoma*** - **Homer rosettes** are characteristic histopathological findings associated with neuroblastoma, indicating differentiation [1]. - This type of cancer typically occurs in **children**, primarily arising from the **adrenal glands** or sympathetic nervous system [1]. *Hepatoma* - Primarily affects the **liver** and is characterized by the presence of **hepatocytes** rather than Homer rosettes. - Typically associated with underlying **chronic liver disease** such as cirrhosis or hepatitis B/C. *Ependymoma* - Consists of cells arising from **ependymal cells** lining the ventricles of the brain and spinal cord, mainly involves **perivascular pseudorosettes**, not Homer rosettes. - Often presents with symptoms related to **increased intracranial pressure** due to obstruction. *Nephroblastoma* - Commonly known as **Wilms tumor**, it typically presents with a **palpable abdominal mass** in children and does not feature Homer rosettes. - Characterized by a triphasic histological pattern (blastemal, epithelial, and stromal components) rather than neuroblastic differentiation. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 483-485.

Question 346: What is a watershed infarct in the brain?

A. Occurs in the border zones between major arteries (Correct Answer)
B. Occurs in the areas supplied by only one artery
C. Occurs in the terminal portion of main arteries
D. Occurs only in areas with complete arterial occlusion

Explanation: ***Occurs in the border zones between major arteries*** - A **watershed infarct** or **border zone infarct** arises in areas where the **perfusion** from two different arterial territories meets [1]. - These areas are particularly vulnerable to ischemia during periods of **systemic hypoperfusion**, as blood flow is lowest at the "watershed" of these overlapping supply zones [1]. *Occurs in the areas supplied by only one artery* - Infarcts in areas supplied by only one artery are typically seen in **lacunar strokes**, affecting **deep penetrating arteries** and not necessarily watershed areas [2]. - These are often due to occlusion of a single, small perforating artery, leading to a **discrete, localized lesion**. *Occurs only in areas with complete arterial occlusion* - Watershed infarcts result from **systemic hypoperfusion** rather than complete arterial occlusion [1]. - They occur when global reduction in cerebral blood flow affects the **most vulnerable border zones**, even without complete vessel occlusion. - Complete arterial occlusions typically cause **territorial infarcts** in the distribution of that specific artery. *Occurs in the terminal portion of main arteries* - Infarcts in the terminal portions of main arteries are more consistent with **embolic or thrombotic events** directly occluding that specific artery. - A watershed infarct is distinct as it results from a **global reduction in cerebral blood flow**, affecting the *most distal* and *least well-perfused regions*. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 150-151. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1266-1268.

Question 347: Which of the following is a common deformity associated with Chiari Malformation Type II?

A. Syringomyelia
B. Meningomyelocele (Correct Answer)
C. Hydrocephalus
D. None of the options

Explanation: ***Meningomyelocele*** - **Chiari Malformation Type II** is almost always associated with a **meningomyelocele**, a severe form of spina bifida where the spinal cord and nerves protrude through an opening in the spine. - This neural tube defect is considered a hallmark of Chiari Malformation Type II and contributes to many of the associated neurological symptoms. *Syringomyelia* - While **syringomyelia** (a fluid-filled cyst within the spinal cord) can be a **complication** of Chiari Malformation Type I or Type II, it is not a direct anatomical deformity of the malformation itself but rather a secondary effect from altered CSF flow [1]. - It develops in a significant portion of patients but is not the primary associated birth defect defining Chiari Type II. *Hydrocephalus* - **Hydrocephalus** (excessive accumulation of cerebrospinal fluid in the brain) is a very **common complication** of Chiari Malformation Type II due to the obstruction of CSF flow at the level of the hindbrain [1]. - However, like syringomyelia, it is a secondary condition resulting from the primary anatomical malformation (downward displacement of cerebellar tonsils and brainstem) and the associated meningomyelocele, not the core deformity itself. *None of the options* - This option is incorrect because **meningomyelocele** is a direct and defining deformity strongly associated with Chiari Malformation Type II. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 718-719.

Question 348: Which of the following is considered a good prognostic factor for neuroblastoma?

A. MYCN amplification
B. Age greater than 18 months at diagnosis
C. Trk-A expression present (Correct Answer)
D. Presence of 1p deletion

Explanation: ***Trk-A expression present*** - **High TrkA (NTRK1) expression** is a well-established **favorable prognostic marker** in neuroblastoma - Associated with younger age, lower stage disease, and better differentiation - Tumors with high TrkA expression tend to be less aggressive and may undergo **spontaneous regression** [1] - Reflects activation of neurotrophin signaling pathways that promote differentiation rather than proliferation *Presence of 1p deletion* - **1p deletion** is a **poor prognostic factor** in neuroblastoma - Associated with aggressive disease and worse outcomes - The **absence** (not presence) of 1p deletion would be favorable *MYCN amplification* - **MYCN amplification** is the **strongest adverse prognostic factor** in neuroblastoma [1] - Found in approximately 20-25% of cases - Associated with rapid tumor progression, advanced stage, and poor survival - Patients with MYCN amplification are classified as high-risk regardless of other factors *Age greater than 18 months at diagnosis* - **Age > 18 months** is a **poor prognostic factor** - Younger children (especially < 12-18 months) have significantly better outcomes - Age is a key component of neuroblastoma risk stratification systems - Older children tend to present with more advanced disease and have worse response to therapy **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 483-487.

Question 349: What is the most common cerebellar tumor in children?

A. Ependymoma
B. Medulloblastoma (Correct Answer)
C. PNET
D. Astrocytoma

Explanation: ***Medulloblastoma*** - **Medulloblastoma** is the most common **malignant** cerebellar tumor in children, accounting for about 20% of all childhood brain tumors [2]. - In the context of this question, medulloblastoma is considered the "most common cerebellar tumor" as it is the most frequently encountered **malignant** tumor requiring aggressive treatment. - These tumors arise from neuroectodermal cells in the cerebellum and are typically **highly aggressive**, often spreading through the cerebrospinal fluid (CSF) pathways [1], [2]. - Peak incidence is between 5-9 years of age, with a male predominance [1]. *Astrocytoma* - **Cerebellar pilocytic astrocytomas** are actually the most common **benign** cerebellar tumor in children and represent a significant portion of all cerebellar tumors [1]. - However, in competitive exam contexts, when asking about "most common cerebellar tumor," the question typically refers to **malignant tumors**, where medulloblastoma takes precedence. - **Pilocytic astrocytomas** are usually low-grade (WHO Grade I) and have an excellent prognosis, often presenting as cystic lesions with a mural nodule. *Ependymoma* - **Ependymomas** are the third most common posterior fossa tumor in children (after medulloblastoma and pilocytic astrocytoma). - They typically arise from the ependymal lining of the **fourth ventricle**, making them cerebellar-adjacent rather than primarily cerebellar tumors [3], [4]. - They account for about 10% of pediatric brain tumors and have an intermediate prognosis. *PNET* - **PNET (Primitive Neuroectodermal Tumor)** is a historical term that has largely been replaced by more specific classifications in the current WHO CNS tumor classification. - Medulloblastoma was previously classified as a type of PNET, but is now recognized as a distinct entity. - The term PNET is now rarely used in modern neuropathology practice, having been superseded by molecular and genetic classification systems. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 725-726. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1314-1315. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 726-727. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1312-1313.

Question 350: Most common CNS tumor associated with NF1

A. Optic glioma (Correct Answer)
B. Astrocytoma
C. Bilateral acoustic neuroma
D. Optic nerve schwannoma

Explanation: ***Optic glioma*** - **Optic gliomas** (specifically **pilocytic astrocytomas**) are the most common CNS tumor found in association with **Neurofibromatosis type 1 (NF1)** [1]. - These tumors typically affect the **optic nerve** and can cause vision impairment. *Optic nerve schwannoma* - **Schwannomas** are tumors arising from Schwann cells, and while they can affect cranial nerves, an **optic nerve schwannoma** is very rare and not characteristic of NF1. - The most common schwannoma associated with neurofibromatosis is a **vestibular schwannoma** (acoustic neuroma) in NF2, not NF1 [2]. *Astrocytoma* - While optic gliomas are a type of astrocytoma, simply stating "astrocytoma" is too broad; the specific location (optic nerve) and type (pilocytic) are key in NF1 [1]. - Other types of astrocytomas (e.g., glioblastoma) are not typically associated with NF1 as the *most common* CNS tumor. *Bilateral acoustic neuroma* - **Bilateral acoustic neuromas** (vestibular schwannomas) are the hallmark CNS tumor of **Neurofibromatosis type 2 (NF2)**, not NF1 [2]. - This symptom strongly points to NF2, a distinct genetic disorder from NF1 [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1319-1320. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 727-728.

Practice by Chapter

Cellular Pathology of the Nervous System

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Cerebrovascular Diseases

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Trauma to the Central Nervous System

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Infections of the Nervous System

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Demyelinating Diseases

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Neurodegenerative Diseases

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CNS Tumors

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Peripheral Nerve Disorders

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Neuromuscular Junction Diseases

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Congenital and Developmental Disorders

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