Neuropathology — MCQs

A 10-year-old male child with short stature presents with complaints of frequent headaches over the past 6 months, slowly progressive loss of vision of the right eye, difficulty in walking, frequent mood changes, and excessive thirst. MRI brain showed a tumor in the sellar region, which was resected. HPE examination showed reticular epithelial cells with appearances reminiscent of the enamel pulp of developing teeth, along with calcifications and wet keratin nodules. The gene involved in causing this condition is also involved in causing which other condition?

Q266Medium

A 1-year-old boy presents with a delay in motor development. Progressive muscle weakness and blindness ensue, and the patient dies within a year. The brain at autopsy shows swollen neurons that contain numerous lysosomes filled with lipid. Which of the following is the most likely diagnosis?

Q267

Tau protein inclusions are involved in:

Q268

Which among the following best describes 'Neuropraxia'?

Q269

A patient had a road traffic accident (RTA). NCCT head was normal on admission. The patient later died after several days in the ICU due to coma. Brain biopsy revealed multiple punctate hemorrhages. What is the diagnosis?

Q270

The CSF findings in bacterial meningitis would include which of the following?

Neuropathology Indian Medical PG Practice Questions and MCQs

Question 261: Which of the following is not a finding in viral encephalitis?

A. Astroglial proliferation (Correct Answer)
B. Perivascular mononuclear infiltrate
C. Intranuclear and intracytoplasmic inclusion bodies
D. None of the above

Explanation: In viral encephalitis, the central nervous system undergoes specific histopathological changes characterized by direct viral injury and the subsequent immune response. **Explanation of the Correct Answer:** **Astroglial proliferation (Astrogliosis)** is a non-specific reactive process of the CNS to various forms of injury, including trauma, ischemia, and chronic neurodegeneration. While it can occur as a late-stage repair mechanism (scarring) following any brain insult, it is **not** a diagnostic or hallmark finding of acute viral encephalitis. The primary cellular response in the acute phase of viral infection involves microglia (microglial nodules) rather than astrocytes [1]. **Analysis of Incorrect Options:** * **Perivascular mononuclear infiltrate:** This is a classic hallmark of viral encephalitis [1]. Lymphocytes, plasma cells, and macrophages aggregate around blood vessels (often called "perivascular cuffing"), representing the body's inflammatory response to the virus. * **Intranuclear and intracytoplasmic inclusion bodies:** These are pathognomonic features where viral replication occurs. Examples include **Negri bodies** (intracytoplasmic) [2] in Rabies and **Cowdry Type A** (intranuclear) [1] in Herpes Simplex Virus (HSV). **High-Yield Clinical Pearls for NEET-PG:** * **Microglial Nodules:** Small clusters of microglia around areas of necrosis are a characteristic finding in viral infections [1]. * **Neuronophagia:** The process where macrophages/microglia ingest necrotic neurons. * **HSV Encephalitis:** Most common cause of sporadic fatal encephalitis; typically involves the **temporal lobes** [1]. * **CMV Encephalitis:** Characterized by "Owl’s eye" intranuclear inclusions. * **Subacute Sclerosing Panencephalitis (SSPE):** Caused by persistent Measles virus; shows both intranuclear and intracytoplasmic inclusions. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, p. 1278. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1279-1280.

Question 262: Lisch nodules (Pigmented Iris hamartomas) are seen in which condition?

A. Niemann Pick disease
B. Neurofibromatosis (Correct Answer)
C. Ochronosis
D. Glycogen storage disease

Explanation: **Explanation:** **Neurofibromatosis Type 1 (NF1)**, also known as von Recklinghausen disease, is an autosomal dominant neurocutaneous syndrome caused by a mutation in the *NF1* gene on chromosome 17. **Lisch nodules** are the most common ocular manifestation of NF1, occurring in over 90% of affected adults. Pathologically, they are melanocytic hamartomas of the iris—clear, yellow-brown, dome-shaped elevations. While they do not affect vision, they are a critical diagnostic criterion for NF1. **Analysis of Incorrect Options:** * **Niemann-Pick Disease:** A lysosomal storage disorder characterized by sphingomyelinase deficiency. The classic ocular finding is a **"Cherry-red spot"** on the macula, not iris hamartomas. * **Ochronosis (Alkaptonuria):** This involves the accumulation of homogentisic acid. Ocular findings include **scleral pigmentation** (brownish-black spots), typically near the insertion of the rectus muscles, rather than iris nodules. * **Glycogen Storage Disease (GSD):** These are metabolic disorders affecting glycogen breakdown. While some types (like Type I/von Gierke) may show paramacular xanthomas, Lisch nodules are not associated with GSD. **High-Yield Clinical Pearls for NEET-PG:** * **NF1 Diagnostic Criteria (Mnemonic: CAFE SPOT):** **C**afe-au-lait spots (≥6), **A**xillary/inguinal freckling (Crowe sign), **F**ibromas (Neurofibromas) [1], **E**ye (Lisch nodules), **S**keletal bowing/pseudoarthrosis, **P**ositive family history, **O**ptic **T**umor (Optic glioma). * **NF1 vs. NF2:** NF1 is on Chromosome **17** (17 letters in Neurofibromatosis); NF2 is on Chromosome **22** (associated with bilateral acoustic neuromas) [2]. * **Lisch nodules are absent in NF2**, making them a key differentiating feature. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1249-1250. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1319-1320.

Question 263: Which of the following drugs has anxiolytic action with the least sedation?

A. Buspirone (Correct Answer)
B. Triazolam
C. Alprazolam
D. Chlordiazepoxide

Explanation: ### Explanation **Correct Answer: A. Buspirone** **Mechanism and Rationale:** Buspirone is a unique anxiolytic agent that acts as a **selective partial agonist at the 5-HT1A receptors**. Unlike benzodiazepines, it does not interact with the GABA-A receptor complex. Because of its selective serotonergic mechanism, it lacks the sedative, hypnotic, anticonvulsant, and muscle-relaxant properties typical of other anxiolytics. It is the drug of choice for Generalized Anxiety Disorder (GAD) when the patient needs to remain alert (e.g., drivers, students). **Analysis of Incorrect Options:** * **B. Triazolam:** A short-acting benzodiazepine primarily used as a hypnotic for insomnia. It causes significant sedation and has a high risk of rebound insomnia. * **C. Alprazolam:** A potent benzodiazepine used for panic disorders and GAD. While effective, it causes dose-dependent sedation, psychomotor impairment, and carries a risk of dependence. * **D. Chlordiazepoxide:** A long-acting benzodiazepine used mainly for alcohol withdrawal. It has active metabolites that cause prolonged sedation and "hangover" effects. **High-Yield Clinical Pearls for NEET-PG:** * **"The 3 No’s" of Buspirone:** No Sedation, No Tolerance/Dependence (low abuse potential), and No interaction with Alcohol. * **Delayed Onset:** Unlike benzodiazepines, Buspirone takes **2–4 weeks** to show therapeutic effects; it is not useful for acute anxiety or panic attacks. * **Side Effects:** Most common side effects include dizziness, nausea, and headache. * **Metabolism:** It is metabolized by **CYP3A4**; its levels increase significantly if taken with grapefruit juice or rifampin.

Question 264: Which of the following is not seen in Tuberous sclerosis?

A. Shagreen patch
B. Adenoma sebaceum
C. McCollum plaques (Correct Answer)
D. Depigmented nevi

Explanation: **Explanation:** **Tuberous Sclerosis Complex (TSC)** is an autosomal dominant neurocutaneous syndrome (phakomatosis) caused by mutations in the **TSC1 (Hamartin)** or **TSC2 (Tuberin)** genes. It is characterized by the development of benign tumors (hamartomas) in multiple organs [1]. **Why McCollum Plaques is the correct answer:** **McCollum plaques** are irregular endocardial thickenings usually found in the **left atrium**, resulting from jet lesions in **Mitral Regurgitation** (Rheumatic Heart Disease). They have no association with Tuberous Sclerosis. The characteristic cardiac finding in TSC is actually **Cardiac Rhabdomyoma** [1]. **Analysis of Incorrect Options (Features seen in TSC):** * **Shagreen patches:** These are leathery, thickened, "orange-peel" textured skin patches typically found on the lower back (lumbosacral region). They represent connective tissue nevi. * **Adenoma sebaceum:** A misnomer, as these are actually **facial angiofibromas** [1]. They appear as reddish papules in a malar distribution (butterfly area of the face). * **Depigmented nevi:** Also known as **Ash-leaf spots**. These are often the earliest clinical sign of TSC and are best visualized using a **Wood’s lamp**. **High-Yield Clinical Pearls for NEET-PG:** * **Vogt’s Triad:** Seizures, Mental retardation, and Adenoma sebaceum (seen in only ~30% of cases). * **CNS findings:** Cortical tubers, Subependymal nodules (SEN), and **Subependymal Giant Cell Astrocytoma (SEGA)** [1]. * **Renal findings:** Bilateral **Renal Angiomyolipomas** (risk of hemorrhage) [1]. * **Pulmonary findings:** Lymphangioleiomyomatosis (LAM), primarily in females [1]. * **Ungual fibromas:** Also known as Koenen tumors (flesh-colored growths around nails). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1318-1319.

Question 265: A 10-year-old male child with short stature presents with complaints of frequent headaches over the past 6 months, slowly progressive loss of vision of the right eye, difficulty in walking, frequent mood changes, and excessive thirst. MRI brain showed a tumor in the sellar region, which was resected. HPE examination showed reticular epithelial cells with appearances reminiscent of the enamel pulp of developing teeth, along with calcifications and wet keratin nodules. The gene involved in causing this condition is also involved in causing which other condition?

A. Hepatocellular carcinoma (Correct Answer)
B. Melanoma
C. Neuroblastoma
D. Chronic myeloid leukemia

Explanation: **Explanation:** The clinical presentation (short stature, headache, vision loss, and diabetes insipidus/excessive thirst) combined with the MRI location (sellar region) and histopathology (reticular epithelial cells resembling enamel pulp, calcifications, and **"wet keratin"**) confirms a diagnosis of **Adamantinomatous Craniopharyngioma (ACP)**. **1. Why Option A is Correct:** The molecular hallmark of Adamantinomatous Craniopharyngioma is a mutation in the **CTNNB1 gene**, which encodes **β-catenin** (part of the Wnt signaling pathway). This mutation leads to the nuclear accumulation of β-catenin. Mutations in the *CTNNB1* gene are also frequently implicated in the pathogenesis of **Hepatocellular Carcinoma (HCC)**, as well as Desmoid tumors and Medulloblastoma (Wnt subtype). **2. Why Incorrect Options are Wrong:** * **B. Melanoma:** Primarily associated with *BRAF V600E* mutations or *CDKN2A* deletions. While Papillary Craniopharyngiomas (the adult variant) harbor *BRAF V600E* mutations, the histopathology described here (wet keratin/calcification) is specific to the Adamantinomatous type. * **C. Neuroblastoma:** Characterized by *N-MYC* amplification or *ALK* mutations. * **D. Chronic Myeloid Leukemia:** Caused by the *BCR-ABL1* fusion gene (Philadelphia chromosome, t(9;22)). **Clinical Pearls for NEET-PG:** * **Craniopharyngioma:** Derived from **Rathke’s pouch** epithelium. It has a bimodal age distribution (5–15 years and >50 years). * **Adamantinomatous vs. Papillary:** * **Adamantinomatous (Children):** *CTNNB1* mutation, "Machine oil" fluid, calcification, and wet keratin. * **Papillary (Adults):** *BRAF V600E* mutation, lacks calcification and wet keratin. * **Visual Deficit:** Classically causes bitemporal hemianopia due to optic chiasm compression [1]. [2]. [1] PRE-FORMATTED CITATION: "Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 417-418." [2] PRE-FORMATTED CITATION: "Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1084-1085." **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 417-418. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1084-1085.

Question 266: A 1-year-old boy presents with a delay in motor development. Progressive muscle weakness and blindness ensue, and the patient dies within a year. The brain at autopsy shows swollen neurons that contain numerous lysosomes filled with lipid. Which of the following is the most likely diagnosis?

A. AL amyloidosis
B. Hurler syndrome
C. Phenylketonuria
D. Tay-Sachs disease (Correct Answer)

Explanation: **Tay-Sachs Disease** is the correct diagnosis based on the clinical triad of progressive motor delay, neurodegeneration (blindness/weakness), and characteristic histopathology. It is an autosomal recessive lysosomal storage disorder caused by a deficiency of the enzyme **Hexosaminidase A**, leading to the accumulation of **GM2 gangliosides** within neurons [1]. Under the microscope, neurons appear swollen with vacuolated cytoplasm [1]. Electron microscopy reveals pathognomonic **"whorled" onion-skin lysosomes** (lipid-filled bodies) [1]. Clinically, the presence of a **cherry-red spot** on the macula is a classic finding (though not mentioned here, it is highly associated) [1]. **Why other options are incorrect:** * **AL Amyloidosis:** Involves extracellular deposition of monoclonal light chains. It typically affects the heart, kidneys, and tongue in adults, not neuronal lysosomes in infants. * **Hurler Syndrome:** A mucopolysaccharidosis (MPS I) caused by alpha-L-iduronidase deficiency [2]. While it causes developmental delay, it is characterized by **gargoylism** (coarse facies), hepatosplenomegaly, and corneal clouding, rather than isolated lipid-filled neuronal swelling [2]. * **Phenylketonuria (PKU):** A metabolic defect in phenylalanine hydroxylase. It causes intellectual disability and a "mousy" odor, but it does not result in the accumulation of lipid-filled lysosomes in neurons. **NEET-PG High-Yield Pearls:** * **Enzyme Deficient:** Hexosaminidase A (Mnemonic: Tay-Sa**X** lacks He**X**osaminidase) [1]. * **Accumulated Substance:** GM2 Ganglioside [1]. * **Key Finding:** Cherry-red spot on macula (also seen in Niemann-Pick, but Niemann-Pick has hepatosplenomegaly; Tay-Sachs does **not**) [3]. * **Microscopy:** "Onion-skin" appearance of lysosomes [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, p. 161. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 163-164. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 161-162.

Question 267: Tau protein inclusions are involved in:

A. Amyotrophic lateral sclerosis
B. Huntington's disease
C. CNS lymphoma
D. Alzheimer’s disease (Correct Answer)

Explanation: ***Alzheimer's disease*** - **Tau protein** aggregation leads to the formation of **neurofibrillary tangles (NFTs)**, which are characteristic pathological hallmarks of Alzheimer's disease, particularly in the hippocampus and cortex [1]. - Hyperphosphorylation of Tau causes it to dissociate from microtubules, destabilizing the neuronal cytoskeleton and ultimately leading to **synaptic dysfunction** and cell death [2]. *Huntington's disease* - This disorder is caused by an expansion of a **CAG triplet repeat** in the *HTT* gene, leading to the accumulation of misfolded **Huntingtin protein**. - It is characterized by atrophy of the **caudate nucleus** and putamen (striatum) and is not primarily linked to Tauopathies. *Amyotrophic lateral sclerosis* - ALS is primarily characterized by the aggregation of **TDP-43** (Tar DNA-binding protein 43) in motor neurons, a distinct type of proteinopathy. - While some cases of ALS overlap with Frontotemporal Dementia (FTD) which can involve Tauopathies, classic ALS pathology is defined by **TDP-43 inclusions**. *CNS lymphoma* - CNS lymphoma is a **primary central nervous system (CNS) tumor**, usually a non-Hodgkin B-cell lymphoma. - Diagnosis relies on identifying atypical lymphoid cells and is not associated with misfolded Tau protein inclusions, which are features of **neurodegenerative diseases** [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1292-1295. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 721-722. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1288-1289.

Question 268: Which among the following best describes 'Neuropraxia'?

A. Intact axon; Damaged nerve sheath (Correct Answer)
B. None of the above
C. Damaged axon and nerve sheath
D. Damaged axon; Intact nerve sheath

Explanation: ***Intact axon; Damaged nerve sheath*** - This correctly describes **Neuropraxia**, the mildest form of nerve injury, where there is localized damage to the **myelin sheath** causing a temporary conduction block [1]. - The **axon** and connective tissue layers (**endoneurium**, **perineurium**, and **epineurium**) remain intact, allowing for complete and relatively rapid recovery once the compression is relieved. *Damaged axon; Intact nerve sheath* - This description corresponds to **Axonotmesis**, a more severe injury where the axon is disrupted, leading to **Wallerian degeneration** distal to the lesion [2]. - The surrounding connective tissue sheaths remain intact, which provides a scaffold for axonal regeneration, though recovery is slower and less complete than in neuropraxia. *Damaged axon and nerve sheath* - This describes **Neurotmesis**, the most severe type of nerve injury, involving complete transection of the axon and its surrounding connective tissue sheaths [2]. - Due to the disruption of the entire nerve trunk, spontaneous recovery is unlikely, and **surgical intervention** is often required to restore function. *None of the above* - This option is incorrect as the first option accurately defines **Neuropraxia** according to Seddon's classification of nerve injuries. - The other options describe the more severe forms of nerve injury, **Axonotmesis** and **Neurotmesis**, covering the primary classifications. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, p. 1232. [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 269: A patient had a road traffic accident (RTA). NCCT head was normal on admission. The patient later died after several days in the ICU due to coma. Brain biopsy revealed multiple punctate hemorrhages. What is the diagnosis?

A. Subdural hemorrhage
B. Intraventricular bleeding
C. Ischemic injury
D. Diffuse axonal injury (Correct Answer)

Explanation: ***Diffuse axonal injury*** - This condition is caused by **traumatic shearing forces** due to sudden acceleration-deceleration, as seen in RTAs, leading to widespread axonal damage [1][2]. - A key feature is a discrepancy between clinical severity (e.g., coma) and initial imaging, as non-contrast CT scans are often normal [2]. The presence of **multiple punctate hemorrhages** on biopsy or sensitive MRI sequences (like the one shown) is characteristic [2]. *Ischemic injury* - This results from reduced blood flow causing a stroke, not direct trauma, and presents with focal neurological deficits corresponding to an arterial territory [3]. - Pathologically, it leads to **liquefactive necrosis** in a specific vascular distribution, not diffuse punctate hemorrhages [3]. *Intraventricular bleeding* - This refers to hemorrhage within the ventricular system and would be clearly visible as a **hyperdensity** on an initial NCCT head scan [3]. - It is a distinct type of intracranial bleed and does not present as microscopic, diffuse parenchymal hemorrhages [3]. *Subdural hemorrhage* - This involves bleeding into the space between the dura and arachnoid mater, usually from torn bridging veins. - It appears as a **crescent-shaped** hyperdensity on a CT scan and is typically evident immediately after trauma. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 700-701. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 701-702. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 706-707.

Question 270: The CSF findings in bacterial meningitis would include which of the following?

A. Elevated WBC count with normal glucose
B. Decreased protein and elevated glucose
C. Normal white blood cell count
D. Elevated protein and decreased glucose (Correct Answer)

Explanation: **Elevated protein and decreased glucose (Correct)** - The inflammation and damage to the **blood-brain barrier** during bacterial infection allow large plasma proteins to leak into the CSF, causing **elevated protein** levels [1]. - Bacteria rapidly metabolize CSF **glucose**, or transport into the CSF is impaired, resulting in characteristically **low (decreased) glucose** levels (typically <40 mg/dL or CSF:blood glucose ratio <0.4) [1]. - This combination (high protein + low glucose + neutrophilic pleocytosis) forms the **classic CSF triad** of bacterial meningitis [1]. *Normal white blood cell count (Incorrect)* - Bacterial meningitis triggers a marked inflammatory response, resulting in severe CSF **pleocytosis** (high WBC count), often exceeding 1000 cells/mm³ [1]. - The primary cell type is usually **neutrophils** (**polymorphonuclear leukocytes**), which rules out a normal WBC count [1]. *Decreased protein and elevated glucose (Incorrect)* - CSF protein is typically **elevated** in bacterial meningitis due to compromised blood-brain barrier integrity, making 'decreased protein' incorrect [1]. - **Elevated glucose** is contrary to the hallmark finding of severe hypoglycemia (low glucose) caused by bacterial consumption and impaired glucose transport [1]. *Elevated WBC count with normal glucose (Incorrect)* - Although CSF **WBC count is elevated** (pleocytosis), a **normal glucose** level is incompatible with established bacterial meningitis, where glucose is characteristically low [1]. - Elevated WBC with normal glucose is more suggestive of conditions like early **viral meningitis** or some non-infectious inflammatory disorders [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 708-709. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1274-1275.

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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