Neuropathology Practice Questions

Q: Which of the following conditions is associated with brain tumors?

Sturge-Weber syndrome. **Explanation:** The correct answer is **Sturge-Weber Syndrome (SWS)**. While SWS is a classic phakomatosis characterized by vascular malformations, it is unique among the listed options because it is **not** typically associated with the development of brain tumors (neoplasms). Instead, it is characterized by a **leptomeningeal angioma** (a vascular malformation), usually involving the pia mater of the occipital and parietal lobes. This leads to cortical atrophy and "tram-track" calcifications rather than neoplastic growth. **Analysis of Options:** * **Neurofibromatosis (Type 1 & 2):** Strongly associated with brain tumors [1]. NF1 is linked to Optic Nerve Gliomas and Astrocytomas; NF2 is famous for the "MISME" mnemonic (Multiple Inherited Schwannomas, Meningiomas, and Ependymomas). * **Tuberous Sclerosis (TSC):** Characterized by **Subependymal Giant Cell Astrocytomas (SEGA)** and cortical tubers (which are hamartomas, but SEGA is a distinct neoplasm) [1],[2]. * **Von Hippel-Lindau (VHL) Syndrome:** Highly associated with **Hemangioblastomas**, particularly in the cerebellum and brainstem [1]. **NEET-PG High-Yield Pearls:** * **Sturge-Weber Syndrome:** Look for the triad of Port-wine stain (Nevus flammeus in V1/V2 distribution), Leptomeningeal angioma, and Glaucoma. It is caused by a somatic mutation in the **GNAQ gene**. * **Radiology:** "Tram-track" calcifications on CT are a classic finding in SWS due to cortical mineralization. * **Rule of Thumb:** Most phakomatoses (NF1, NF2, TSC, VHL) are autosomal dominant and predispose to tumors; SWS is **sporadic** and primarily **vascular/malformative** in nature. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 724-725. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1318-1320.

Q: Spinal muscular atrophy is seen in lesions of which of the following structures?

Anterior horn. **Explanation:** **Spinal Muscular Atrophy (SMA)** is a genetic neuromuscular disorder [1] characterized by the progressive degeneration of **Lower Motor Neurons (LMNs)** [2]. **Why Option A is correct:** The pathology of SMA specifically involves the **Anterior Horn Cells (AHCs)** of the spinal cord. These cells are the cell bodies of lower motor neurons [2]. Their degeneration leads to muscle denervation, resulting in symmetric muscle weakness and profound atrophy [1]. Since the primary lesion is at the level of the spinal cord's gray matter (anterior horn), it is classified as a "neuronopathy" [1]. **Why other options are incorrect:** * **Option B (Peripheral nerve):** Lesions here cause peripheral neuropathies (e.g., Guillain-Barré Syndrome). While they also show LMN signs [2], the primary pathology in SMA is the cell body itself, not the axonal projection. * **Option C (Neuromuscular junction):** Disorders here (e.g., Myasthenia Gravis) typically present with fatigable weakness without significant muscle atrophy or fasciculations [3]. * **Option D:** SMA is etiologically specific to the anterior horn; therefore, "any of the above" is incorrect. **High-Yield Clinical Pearls for NEET-PG:** * **Genetics:** SMA is most commonly caused by a mutation/deletion in the **SMN1 gene** (Survival Motor Neuron 1) on chromosome **5q**. * **Clinical Features:** Presents with "floppy infant" syndrome (hypotonia) [1], tongue fasciculations, and absent deep tendon reflexes. * **Classification:** * Type 1 (Werdnig-Hoffmann): Most severe, onset <6 months. * Type 3 (Kugelberg-Welander): Milder, juvenile onset. * **Differential Diagnosis:** Polio also affects the Anterior Horn Cells but is viral and usually presents with asymmetrical paralysis, unlike the symmetrical weakness in SMA.

Q: All the following diseases are associated with triplet and other repeat sequences except?

Hereditary motor-sensory neuropathy. ### Explanation The correct answer is **D. Hereditary motor-sensory neuropathy (HMSN)**. #### 1. Why the Correct Answer is Right Hereditary motor-sensory neuropathy, most commonly known as **Charcot-Marie-Tooth (CMT) disease**, is primarily caused by **gene duplications, deletions, or point mutations**, rather than nucleotide repeat expansions [1]. For example, CMT Type 1A (the most common form) results from a **1.5 Mb duplication** of the *PMP22* gene on chromosome 17 [2]. It follows a Mendelian inheritance pattern (mostly Autosomal Dominant) and does not exhibit the phenomenon of "anticipation" seen in repeat expansion disorders. #### 2. Why the Other Options are Wrong The other options are classic examples of **Trinucleotide Repeat Expansion Disorders** [2]: * **Huntington’s Disease (Option A):** Caused by a **CAG** repeat expansion in the *HTT* gene (Chromosome 4). It is an autosomal dominant neurodegenerative disorder. * **Friedreich’s Ataxia (Option B):** Caused by a **GAA** repeat expansion in the *FXN* gene (intron 1) on Chromosome 9. It is unique as it is an **Autosomal Recessive** repeat disorder. * **Myotonic Dystrophy (Option C):** Type 1 (DM1) is caused by a **CTG** repeat expansion in the *DMPK* gene on Chromosome 19. #### 3. High-Yield Clinical Pearls for NEET-PG * **Anticipation:** This is the hallmark of triplet repeat disorders, where the disease becomes more severe or has an earlier onset in successive generations as the repeat length increases [2]. * **Fragile X Syndrome:** Caused by **CGG** repeats; it is the most common inherited cause of intellectual disability. * **Spinobulbar Muscular Atrophy (Kennedy’s Disease):** Another high-yield **CAG** repeat disorder. * **Memory Tool:** * **C**AG: **C**audate degeneration (Huntington’s) * **C**TG: **C**ataracts, **T**oupee (balding), **G**onadal atrophy (Myotonic Dystrophy) * **G**AA: **G**ait **A**taxia (Friedreich’s)

Question 1

A 30-year-old woman suffers a tonic-clonic seizure and presents with delirium and hydrophobia after being bitten on the hand by a bat approximately one month prior. The patient subsequently dies of respiratory failure. Autopsy reveals viral particles throughout the brainstem and cerebellum. In addition to direct viral cytotoxicity, by which primary mechanism is the necrosis of virally infected neurons mediated in this patient?

Accepted Answer

Humoral and cellular immunity

Answer

Histamine release from mast cells

Answer

Neutrophil-mediated phagocytosis

Answer

Release of oxygen radicals from macrophages

Question 2

A 42-year-old immunosuppressed male presents with rapidly progressing neurologic symptoms including mental deterioration, visual loss, abnormal speech, and ataxia. Radiographic studies demonstrate multifocal lesions in the white matter without mass effect. A stereotactic brain biopsy reveals areas of demyelination. Which histologic feature is most likely to be present in this patient?

Accepted Answer

Viral particles within oligodendrocytes

Answer

Beta-A4 amyloid within blood vessels

Answer

Prion protein within extracellular plaques

Answer

Rosenthal fibers within astrocytes

Question 3

Which of the following conditions is associated with brain tumors?

Accepted Answer

Sturge-Weber syndrome

Answer

Tuberous sclerosis

Answer

Von Hippel-Lindau syndrome

Answer

Neurofibromatosis

Question 4

Spinal muscular atrophy is seen in lesions of which of the following structures?

Accepted Answer

Anterior horn

Answer

Peripheral nerve

Answer

Neuromuscular junction

Answer

Any of the above

Question 5

Enamel-like superstructure is seen in which CNS lesion?

Accepted Answer

Craniopharyngioma

Answer

Pituitary tumor

Answer

Astrocytoma

Answer

Glioma

Question 6

A 10-year-old boy presents with increasing muscle weakness and elevated creatine phosphokinase (CPK) levels. What is the most likely structure with a defect causing these symptoms?

Accepted Answer

Muscle fibers

Answer

Nerves

Answer

Basement membrane

Answer

All body cells

Question 7

A 55-year-old man presents with a 3-month history of progressive mental deterioration, including memory loss, mood changes, and impaired judgment. He exhibits an unsteady gait and requires assistance to prevent falls. He has no history of seizures, head trauma, or incontinence. Computed tomography (CT) scan and lumbar puncture are unremarkable. Physical examination reveals hypertonicity of all extremities, bilateral equivocal plantar responses, ataxic gait, and myoclonic jerks in the lower extremities. What is the mechanism by which this infectious agent causes its pathology?

Accepted Answer

Amyloid deposition

Answer

Autoimmune destruction

Answer

Chronic inflammation

Answer

Embolization and infarction

Question 8

What is the characteristic pathological manifestation in Rabies?

Accepted Answer

Brainstem encephalitis

Answer

Ventriculitis

Answer

Basal ganglia affection

Answer

Meningitis

Question 9

All the following diseases are associated with triplet and other repeat sequences except?

Accepted Answer

Hereditary motor-sensory neuropathy

Answer

Huntington's disease

Answer

Friedreich's ataxia

Answer

Myotonic dystrophy

Question 10

Which of the following carcinomas most frequently metastasizes to the brain?

Accepted Answer

Small cell carcinoma of the lung

Answer

Prostate cancer

Answer

Rectal carcinoma

Answer

Endometrial cancer

Neuropathology — MCQs

Neuropathology — MCQs

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