Neurology Practice Questions

Q: A 36-year-old male with a family history of suicide and abnormal movements with dementia is investigated. What is the investigation of choice?

Trinucleotide repeats. **Explanation:** The clinical presentation of **abnormal movements (chorea)**, **dementia**, and a **family history of psychiatric illness (suicide)** in a young adult is a classic description of **Huntington’s Disease (HD)**. 1. **Why Trinucleotide Repeats is correct:** Huntington’s Disease is an autosomal dominant neurodegenerative disorder caused by an unstable expansion of **CAG trinucleotide repeats** in the *HTT* gene on chromosome 4. Genetic testing to quantify these repeats is the **gold standard and investigation of choice** for definitive diagnosis. A repeat count of ≥40 is fully penetrant for the disease. 2. **Why other options are incorrect:** * **Psychological examination:** While useful for assessing the severity of dementia or depression, it cannot provide a definitive diagnosis of the underlying genetic pathology. * **ECG:** Has no diagnostic value for HD; it is used for cardiac evaluation. * **MRI:** While MRI may show characteristic **atrophy of the caudate nucleus** (leading to "boxcar ventricles"), these changes often appear later in the disease. Genetic testing remains superior for early and definitive diagnosis. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Autosomal Dominant with **Anticipation** (earlier onset in successive generations, especially when inherited from the father). * **Pathology:** Loss of GABAergic neurons in the Striatum (Caudate + Putamen). * **Neurotransmitters:** Decreased GABA and Acetylcholine; Increased Dopamine. * **Triad:** Motor (Chorea), Cognitive (Dementia), and Psychiatric (Depression/Suicidality) symptoms.

Q: Which one of the following is an example of Motor Neuropathy?

Dapsone neuropathy. Peripheral neuropathies are classified based on the type of nerve fibers involved: sensory, motor, or mixed (sensorimotor) [1]. Most neuropathies are mixed, making pure motor or pure sensory presentations high-yield for exams. ### **Explanation of the Correct Answer** **B. Dapsone neuropathy:** Dapsone (used in Leprosy and Dermatitis Herpetiformis) is a classic cause of a **predominantly motor, axonal neuropathy**. It typically presents with wasting and weakness of the small muscles of the hands and feet. Unlike the sensory loss seen in Leprosy itself, Dapsone toxicity specifically targets motor neurons. Other classic motor neuropathies include Lead poisoning, Guillain-Barré Syndrome (GBS), and Porphyria [1]. ### **Analysis of Incorrect Options** * **A. Sjogren’s syndrome:** This is characteristically associated with **Sensory Neuronopathy** (Ganglionopathy) due to inflammation of the dorsal root ganglia. It presents with sensory ataxia and "sicca" symptoms [2]. * **C. Tangier disease:** This is a rare genetic disorder of cholesterol transport. It typically presents with a **syringomyelia-like syndrome** (dissociated sensory loss) and orange-colored tonsils [1]. * **D. Amyloidosis:** This typically causes a **Small-Fiber Sensory Neuropathy**, often presenting with painful dysesthesia and early autonomic dysfunction. It is also a common cause of Carpal Tunnel Syndrome [3]. ### **NEET-PG High-Yield Pearls** * **Pure Motor Neuropathies (Mnemonic: "L-DOPA"):** **L**ead poisoning (radial nerve/wrist drop), **D**apsone, **O**rganophosphates, **P**orphyria, **A**cute Inflammatory Demyelinating Polyradiculoneuropathy (GBS) [1]. * **Pure Sensory Neuropathies:** Sjogren’s, Vitamin B6 toxicity, Cisplatin, and Paraneoplastic syndromes (Anti-Hu) [2]. * **Lead Poisoning vs. Dapsone:** Both cause motor neuropathy, but Lead poisoning characteristically spares the Brachioradialis muscle.

Q: Pure word blindness occurs due to lesion in which artery?

Posterior cerebral artery. **Explanation:** **Pure word blindness**, also known as **Alexia without Agraphia**, is a clinical syndrome where a patient can write but cannot read what they have written [1]. This occurs due to a lesion in the **Posterior Cerebral Artery (PCA)**, specifically involving the **left primary visual cortex** and the **splenium of the corpus callosum**. 1. **Why PCA is correct:** The PCA supplies the occipital lobe and the splenium [3]. A stroke in the left PCA causes a right homonymous hemianopia (loss of the right visual field) [2]. Because the splenium is also infarcted, visual information from the intact right occipital lobe cannot cross over to the language centers (Angular gyrus) in the left hemisphere [1]. Thus, the patient can see words but cannot process or "read" them. 2. **Why other options are incorrect:** * **Anterior Cerebral Artery (ACA):** Supplies the medial surface of the frontal and parietal lobes. Lesions typically result in contralateral lower limb weakness and urinary incontinence. * **Middle Cerebral Artery (MCA):** Supplies the lateral convexity of the brain, including Broca’s and Wernicke’s areas [1]. An MCA stroke would typically cause **Aphasia** (difficulty speaking or understanding) and **Agraphia** (inability to write), rather than pure word blindness. * **Spinal Artery:** Supplies the spinal cord; it has no role in higher cortical functions like reading or vision. **High-Yield Clinical Pearls for NEET-PG:** * **Dejerine Syndrome:** Another name for Alexia without Agraphia. * **Angular Gyrus Lesion:** Results in **Alexia WITH Agraphia** (Gerstmann Syndrome), usually involving the MCA territory [1]. * **Macular Sparing:** A classic sign of PCA territory infarcts due to collateral supply from the MCA to the occipital pole.

Q: A patient presents with intermittent weakness in the proximal group of muscles and fatigability, along with ptosis. Which of the following is the most definite test to detect the abnormality?

Endrophonium test. **Explanation:** The clinical presentation of intermittent proximal muscle weakness, fatigability, and ptosis is classic for **Myasthenia Gravis (MG)**. MG is an autoimmune disorder caused by antibodies against the postsynaptic acetylcholine receptors (AChR) at the neuromuscular junction [1]. **Why the Correct Answer is Right:** The **Edrophonium (Tensilon) test** is a rapid pharmacological test used to diagnose MG. Edrophonium is a short-acting acetylcholinesterase inhibitor. By preventing the breakdown of acetylcholine in the synaptic cleft, it increases the availability of the neurotransmitter to bind to the remaining functional receptors [1]. In patients with MG, this results in a dramatic, albeit brief, improvement in muscle strength (especially ptosis or ophthalmoparesis), confirming the diagnosis. **Why Other Options are Incorrect:** * **Muscle Biopsy:** This is used to diagnose inflammatory myopathies (like Polymyositis) or muscular dystrophies. In MG, the muscle tissue itself is histologically normal. * **Creatine Phosphokinase (CPK):** CPK levels are markers of muscle fiber necrosis. They are elevated in myopathies and dystrophies but remain **normal** in Myasthenia Gravis. * **Electromyography (EMG):** While Repetitive Nerve Stimulation (RNS) and Single-fiber EMG (SFEMG) are diagnostic tools for MG, a standard needle EMG is primarily used to differentiate between neurogenic and primary myogenic disorders [2]. **NEET-PG Clinical Pearls:** * **Gold Standard/Most Sensitive Test:** Single-fiber EMG (SFEMG) is the most sensitive clinical test for MG [2]. * **Most Specific Test:** Anti-AChR antibody titer. * **Ice Pack Test:** A simple bedside alternative; cooling improves neuromuscular transmission and resolves ptosis in MG. * **Safety Note:** Always have **Atropine** ready during an Edrophonium test to counteract potential cholinergic side effects (bradycardia).

Q: Commonest cause of cerebral infarction is?

Arterial thrombosis. ### Explanation **Correct Option: A. Arterial Thrombosis** Cerebral infarction (Ischemic Stroke) occurs when blood supply to a part of the brain is interrupted [1]. **Arterial thrombosis** is the most common underlying mechanism, typically arising from **atherosclerosis** of large intra- or extracranial arteries (e.g., Carotid artery bifurcation or Middle Cerebral Artery). The formation of a thrombus over a ruptured atherosclerotic plaque leads to local occlusion, making it the leading cause of ischemic strokes globally. **Analysis of Incorrect Options:** * **B. Arteritis:** While inflammatory conditions like Giant Cell Arteritis or Takayasu Arteritis can cause strokes, they are rare compared to degenerative atherosclerotic disease. * **C. Venous Thrombosis:** Cerebral Venous Sinus Thrombosis (CVST) is a distinct entity often presenting with headache and seizures [1]. It accounts for less than 1% of all strokes and usually affects younger patients or those in a prothrombotic state (e.g., pregnancy). * **D. Embolism:** Cardioembolism (often due to Atrial Fibrillation) is the second most common cause. While significant, statistically, local arterial thrombotic events (including small vessel lacunar infarcts) occur more frequently in the general population. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site of cerebral thrombosis:** The bifurcation of the **Common Carotid Artery**. * **Most common vessel involved in stroke:** **Middle Cerebral Artery (MCA)** [1]. * **Gold Standard Investigation:** **Non-Contrast CT (NCCT) Head** is the initial investigation of choice to rule out hemorrhage. **MRI (Diffusion-Weighted Imaging)** is the most sensitive for early ischemic changes (within minutes). * **Therapeutic Window:** Intravenous thrombolysis (Alteplase) should ideally be administered within **4.5 hours** of symptom onset.

Q: Anomic aphasia is due to a defect in which area of the brain?

Temporal-occipital region. **Explanation:** **Anomic aphasia** is characterized by a persistent inability to retrieve names for objects, people, or events, despite having fluent speech, intact repetition, and good comprehension. 1. **Why the Temporal-occipital region is correct:** The retrieval of nouns and names depends on the integration of visual recognition and language processing. The **angular gyrus** and the **junction of the temporal and occipital lobes** (specifically the inferior temporal cortex) are critical for "lexical retrieval." [1] Lesions in the temporal-occipital region disrupt the pathways that connect visual representations to their linguistic labels, leading to the isolated naming deficits seen in anomic aphasia. 2. **Analysis of Incorrect Options:** * **A. Left inferior frontal lobe:** This is the site of **Broca’s area** (Brodmann areas 44, 45). Damage here results in Broca’s aphasia, characterized by non-fluent, "telegraphic" speech and impaired repetition. [1] * **B. Parietal lobe:** While the angular gyrus is in the parietal lobe, isolated parietal lesions more commonly present with **Gerstmann Syndrome** (acalculia, agraphia, finger agnosia, right-left disorientation) rather than pure anomic aphasia. * **D. Cerebellum:** The cerebellum is primarily involved in motor coordination and balance. While it has some cognitive roles, it is not a primary site for language processing or naming. **High-Yield Clinical Pearls for NEET-PG:** * **Anomia** is the most common residual symptom of all recovering aphasias. * **Broca’s Aphasia:** Non-fluent, Repetition impaired, Comprehension intact. * **Wernicke’s Aphasia:** Fluent (word salad), Repetition impaired, Comprehension impaired. * **Conduction Aphasia:** Damage to the **arcuate fasciculus**; hallmark is severely impaired repetition with intact fluency and comprehension. [1]

Question 1

A 36-year-old male with a family history of suicide and abnormal movements with dementia is investigated. What is the investigation of choice?

Accepted Answer

Trinucleotide repeats

Answer

Psychological examination

Answer

ECG

Answer

MRI

Question 2

Which one of the following is an example of Motor Neuropathy?

Accepted Answer

Dapsone neuropathy

Answer

Sjogren's syndrome

Answer

Tangier disease

Answer

Amyloidosis

Question 3

Pure word blindness occurs due to lesion in which artery?

Accepted Answer

Posterior cerebral artery

Answer

Anterior cerebral artery

Answer

Middle cerebral artery

Answer

Spinal artery

Question 4

A 35-year-old female presented with paresthesias and weakness of bilateral lower limbs, a band-like sensation of tightness around the torso, painful loss of vision in both eyes, diplopia, and periorbital pain. She has a history of similar attacks with periods of normalcy in between. On examination, ataxia, papillitis (on fundus examination), facial myokymia, bladder incontinence, and constipation were noted. CSF studies revealed mononuclear cell pleocytosis along with increased IgG. Which of the following are the oral drugs approved for the above condition?

Accepted Answer

Natalizumab

Answer

Fingolimod

Answer

Teriflunomide

Answer

Glatiramer acetate

Question 5

A patient presents with intermittent weakness in the proximal group of muscles and fatigability, along with ptosis. Which of the following is the most definite test to detect the abnormality?

Accepted Answer

Endrophonium test

Answer

Muscle biopsy

Answer

Creatine phosphokinase (CPK)

Answer

Electromyography (EMG)

Question 6

Commonest cause of cerebral infarction is?

Accepted Answer

Arterial thrombosis

Answer

Arteritis

Answer

Venous thrombosis

Answer

Embolism

Question 7

A patient with a history of weakness of one side presented with altered sensorium. A CT scan was performed and showed findings suggestive of a large ischemic stroke with significant edema. What is the most appropriate immediate management?

Accepted Answer

Intravenous mannitol

Answer

Decompressive craniotomy

Answer

Observe and follow-up

Answer

Aspirin

Question 8

Anomic aphasia is due to a defect in which area of the brain?

Accepted Answer

Temporal-occipital region

Answer

Left inferior frontal lobe

Answer

Parietal lobe

Answer

Cerebellum

Question 9

In an EEG, a generalized, symmetric, 3-Hz spike-and-wave discharge that begins and ends suddenly, superimposed on a normal EEG background, is observed. What is the diagnosis?

Accepted Answer

Absence seizures

Answer

Tonic-clonic seizures

Answer

Simple partial seizures

Answer

Complex partial seizures

Question 10

Which of the following is an example of subcortical dementia?

Accepted Answer

Huntington's disease

Answer

Alzheimer's disease

Answer

Creutzfeldt-Jakob disease

Answer

Frontotemporal dementia

Neurology — MCQs

Neurology — MCQs

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