Neurology Practice Questions

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]

Q: What is the distribution of weakness in pyramidal tract lesions?

Antigravity muscles are spared. In a **pyramidal tract lesion** (Upper Motor Neuron lesion), weakness follows a characteristic distribution known as **"pyramidal weakness."** This pattern is defined by the selective involvement of muscle groups based on their function rather than individual nerves. ### **Explanation of the Correct Answer** The hallmark of pyramidal lesions is that **antigravity muscles are relatively spared**, while their antagonists are more severely affected. Antigravity muscles are those that maintain an upright posture against gravity: **Flexors in the upper limbs** and **Extensors in the lower limbs**. Because these muscles are spared (stronger), the patient develops the classic "hemiplegic posture" (flexed arm and extended leg). ### **Analysis of Incorrect Options** * **Option A & B:** These are reversed. In pyramidal lesions, **Flexors are weaker than Extensors in the lower limb**, and **Extensors are weaker than Flexors in the upper limb**. The weaker muscles are always the "non-antigravity" groups. * **Option C:** Antigravity muscles are the strongest groups in a UMN lesion; they are not the primary site of weakness. ### **High-Yield Clinical Pearls for NEET-PG** * **Wernicke-Mann Type of Hemiplegia:** This refers to the characteristic posture resulting from pyramidal weakness—Adducted shoulder, flexed elbow/wrist, and extended hip/knee with circumduction gait. * **Spasticity:** Pyramidal lesions result in "Clasp-knife spasticity," which predominantly affects the stronger antigravity muscles. * **Babinski Sign:** The most reliable clinical sign of a pyramidal (Corticospinal) tract lesion. * **Rule of Thumb:** Weakness is maximal in **distal** muscle groups (fine movements) compared to proximal ones.

Q: Which of the following increases the risk of Parkinsonism?

Nicotine. **Explanation:** The question asks for a factor that **increases** the risk of Parkinsonism. While the provided answer key indicates **Nicotine**, this is a known **protective factor** in medical literature. However, in the context of competitive exams like NEET-PG, it is crucial to distinguish between "Parkinson’s Disease" (idiopathic) and "Parkinsonism" (the clinical syndrome). **1. Why Nicotine (Correct Answer per key):** Epidemiological studies consistently show an **inverse relationship** between cigarette smoking and Parkinson’s Disease (PD). Nicotine is thought to be neuroprotective by stimulating nicotinic acetylcholine receptors on dopaminergic neurons and inducing CYP enzymes that detoxify neurotoxins. *Note: If the question intended to ask for a risk factor, MPTP or Head Injury would be clinically more accurate; if it asks for a "factor associated with the condition," Nicotine is a high-yield association.* **2. Analysis of Other Options:** * **MPTP (B):** This is a potent neurotoxin. It is converted to MPP+ in the brain, which destroys dopaminergic neurons in the substantia nigra, causing **acute, permanent Parkinsonism**. * **Parkin Gene (C):** Mutations in the *PARK2* gene (encoding the protein Parkin) are the most common cause of **autosomal recessive juvenile Parkinson’s**. * **Head Injury (D):** Repeated head trauma (e.g., Dementia Pugilistica) is a recognized risk factor for secondary Parkinsonism. **High-Yield Clinical Pearls for NEET-PG:** * **Protective Factors for PD:** Nicotine (Smoking), Caffeine, and NSAIDs. * **MPTP Mechanism:** It inhibits **Complex I** of the mitochondrial electron transport chain. * **Pathology:** The hallmark is the **Lewy Body**, composed of **alpha-synuclein** [2]. * **Drug-Induced Parkinsonism:** Most commonly caused by antipsychotics (D2 blockers) like Haloperidol or anti-emetics like Metoclopramide [1].

Q: A 26-year-old IT employee presents with sudden onset of 'thunderclap headache' followed by unconsciousness. There is no history of head trauma. Examination reveals unilateral loss of light reflex and pupillary dilation. What is the most probable diagnosis in this patient?

Aneurysmal subarachnoid hemorrhage. ### Explanation **Correct Answer: B. Aneurysmal subarachnoid hemorrhage (SAH)** The clinical presentation of a **"thunderclap headache"** (maximal intensity at onset, often described as the "worst headache of life") followed by a loss of consciousness is the classic hallmark of a Subarachnoid Hemorrhage [1]. In a young patient with no history of trauma, the most common cause is the rupture of a **saccular (berry) aneurysm**. [2] The physical finding of **unilateral pupillary dilation and loss of light reflex** indicates a **3rd Cranial Nerve (Oculomotor) palsy**. This is a high-yield clinical sign suggesting an aneurysm at the junction of the **Posterior Communicating Artery (PComA)** and the Internal Carotid Artery, as the enlarging aneurysm or hematoma compresses the nerve. **Why other options are incorrect:** * **Extradural Hemorrhage (EDH):** While it can cause pupillary changes (uncal herniation), it is almost always associated with **significant head trauma** and typically shows a "lucid interval," which is absent here. * **Basilar Migraine:** Can cause headache and neurological symptoms (vertigo, ataxia), but it does not present with sudden unconsciousness or a fixed dilated pupil. * **Cluster Headache:** Presents as severe, unilateral periorbital pain with autonomic features (lacrimation, ptosis, miosis), not mydriasis or sudden coma. **NEET-PG High-Yield Pearls:** * **Gold Standard Investigation:** Digital Subtraction Angiography (DSA). * **Initial Investigation of Choice:** Non-contrast CT (NCCT) Head (shows hyperdensity in basal cisterns) [1]. * **ECG Changes in SAH:** Tall T-waves (Cerebral T-waves), ST-depression, or QT prolongation due to catecholamine surge. * **Complication:** Vasospasm (prevented with **Nimodipine**).

Question 1

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 2

Commonest cause of cerebral infarction is?

Accepted Answer

Arterial thrombosis

Answer

Arteritis

Answer

Venous thrombosis

Answer

Embolism

Question 3

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 4

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 5

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 6

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

Question 7

What is the distribution of weakness in pyramidal tract lesions?

Accepted Answer

Antigravity muscles are spared

Answer

Extensors are more affected than flexors in the lower limb

Answer

Flexors are more affected than extensors in the upper limb

Answer

Antigravity muscles are affected

Question 8

Which of the following increases the risk of Parkinsonism?

Accepted Answer

Nicotine

Answer

MPTP

Answer

Parkin gene

Answer

Head injury

Question 9

A 26-year-old IT employee presents with sudden onset of 'thunderclap headache' followed by unconsciousness. There is no history of head trauma. Examination reveals unilateral loss of light reflex and pupillary dilation. What is the most probable diagnosis in this patient?

Accepted Answer

Aneurysmal subarachnoid hemorrhage

Answer

Extradural hemorrhage

Answer

Basilar migraine

Answer

Cluster headache

Question 10

Which of the following statements is FALSE regarding decerebrate posturing?

Accepted Answer

Is more dangerous than decorticate posturing

Answer

Often associated with acute brain injuries

Answer

May involve thalamic, midbrain, and frontal lobe lesions

Answer

Characterized by flexion of the arms and extension of the lower limbs

Neurology — MCQs

Neurology — MCQs

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