Neurology Practice Questions

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**).

Q: A patient presents with the CT finding shown in the image. Which one of the following signs is this finding most likely to produce?

Hemiplegia. ***Hemiplegia*** - CT shows a lesion in the **internal capsule**, which contains the **corticospinal tract** responsible for motor control. - Damage to this area causes **pure motor hemiplegia** without sensory or cognitive deficits. *Uniocular blindness* - Requires damage to the **optic nerve** or **central retinal artery**, not the internal capsule. - Would present as **monocular vision loss** with an **afferent pupillary defect**. *Alexia without agraphia* - Results from lesions in the **left occipital lobe** and **splenium of corpus callosum**. - Patients can write but cannot read, requiring **disconnection** between visual and language areas. *Hemiballismus* - Caused by lesions in the **subthalamic nucleus** (body of Luys), not the internal capsule. - Presents as **violent, flinging movements** of the contralateral limbs due to **basal ganglia dysfunction**.

Q: Which of the following conditions has the least chance of causing seizures?

HIV encephalopathy. **Explanation:** The correct answer is **HIV encephalopathy**. In the context of NEET-PG, it is crucial to distinguish between conditions that are "intrinsically epileptogenic" and those that are primarily "degenerative or white-matter involving." [1] **1. Why HIV Encephalopathy is the correct answer:** HIV Encephalopathy (also known as AIDS Dementia Complex) primarily affects the **subcortical white matter** and deep gray matter nuclei. Seizures are typically a manifestation of **cortical** irritation. While patients with HIV can certainly have seizures, they are usually due to secondary opportunistic infections (like Toxoplasmosis or Cryptococcosis) or CNS lymphoma, rather than the direct effect of the HIV virus on the subcortical tissue in encephalopathy. [1] Therefore, it has the lowest intrinsic risk for seizures among the given options. **2. Analysis of incorrect options:** * **Hypoglycemia:** A classic metabolic cause of seizures. Low glucose deprives neurons of energy, leading to membrane instability and massive depolarization. [1] * **Hypocalcemia:** Low ionized calcium lowers the threshold for action potentials by increasing sodium permeability in neuronal membranes, leading to neuromuscular irritability and seizures. [1] * **Neurocysticercosis (NCC):** This is the **most common cause of adult-onset seizures** in developing countries like India. The inflammatory response to the degenerating cyst (scolex) in the cortical parenchyma is highly epileptogenic. **Clinical Pearls for NEET-PG:** * **Most common cause of seizures in HIV patients:** Toxoplasmosis (due to ring-enhancing cortical lesions). * **Metabolic triad of seizures:** Hypoglycemia, Hypocalcemia, and Hyponatremia. [1] * **NCC Staging:** The "Colloidal vesicular" stage is most associated with acute seizures due to the peak inflammatory response.

Q: Which of the following can cause 3rd nerve paralysis?

Midbrain infarct. The **3rd cranial nerve (Oculomotor nerve)** originates from the midbrain at the level of the superior colliculus. Therefore, a **midbrain infarct** (such as Weber’s or Benedikt’s syndrome) directly involves the oculomotor nucleus or its exiting fascicles, leading to ipsilateral 3rd nerve paralysis. [2] **Analysis of Options:** * **A. Posterior Communicating Artery (PCoA) Aneurysm:** While a PCoA aneurysm is a classic cause of "surgical" 3rd nerve palsy (often involving the pupil), it causes compression in the **subarachnoid space**, not within the brainstem itself. In many clinical contexts, this is a correct cause, but in the context of localized neuroanatomy, the midbrain is the primary site of origin. [1] * **B. Tolosa-Hunt Syndrome:** This is an idiopathic granulomatous inflammation of the **cavernous sinus**. While it can cause 3rd nerve palsy, it typically presents as painful ophthalmoplegia involving multiple nerves (III, IV, VI). [1] * **D. Lateral Medullary Lesions (Wallenberg Syndrome):** This affects the medulla, involving nerves IX, X, and XI, along with sympathetic fibers (Horner’s syndrome). It does **not** involve the 3rd nerve, which is located much higher in the brainstem (midbrain). **High-Yield Clinical Pearls for NEET-PG:** * **Rule of Pupil:** Medical causes (e.g., Diabetes) usually spare the pupil because parasympathetic fibers are peripheral. Surgical causes (e.g., PCoA Aneurysm) typically involve the pupil due to external compression. [3] * **Weber’s Syndrome:** Midbrain infarct causing ipsilateral 3rd nerve palsy and contralateral hemiplegia. * **Benedikt’s Syndrome:** Midbrain lesion involving the 3rd nerve and the red nucleus (causing contralateral tremors/ataxia).

Q: Lateral medullary syndrome (Wallenberg syndrome) is characterized by all features EXCEPT:

Horner's syndrome is rare. **Explanation:** Lateral Medullary Syndrome (Wallenberg Syndrome) is a classic brainstem stroke typically caused by occlusion of the **Posterior Inferior Cerebellar Artery (PICA)** or the vertebral artery. **Why Option D is the correct answer:** In Wallenberg syndrome, **Horner’s syndrome is a common and characteristic feature**, not rare [1]. It occurs due to the involvement of the **descending sympathetic tract** located in the lateral medulla [1]. It presents with ipsilateral ptosis, miosis, and anhidrosis. Therefore, stating it is "rare" is clinically incorrect, making it the right choice for an "EXCEPT" question. **Analysis of other options:** * **A. Giddiness:** This is a hallmark symptom caused by involvement of the **vestibular nuclei** and their connections, leading to vertigo, nausea, and nystagmus [2]. * **B. Dysphagia:** This occurs due to damage to the **Nucleus Ambiguus** (affecting CN IX and X), which leads to paralysis of the palatal and pharyngeal muscles, causing dysphagia, dysarthria, and a diminished gag reflex [3]. * **C. Crossed hemianaesthesia:** This is a classic finding [1]. It refers to **ipsilateral** loss of pain and temperature on the face (due to the **Spinal Trigeminal Nucleus**) and **contralateral** loss of pain and temperature on the body (due to the **Lateral Spinothalamic Tract**) [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for PICA Syndrome:** "DANVAH" (Dysarthria/Dysphagia, Ataxia, Nystagmus, Vertigo, Anaesthesia (crossed), Horner’s). * **Key Distinction:** Wallenberg syndrome **spares the Motor system** (Corticospinal tract) and the **Medial Lemniscus** (fine touch/proprioception), as these are located medially. * **Most common cause:** Vertebral artery occlusion is actually more frequent than isolated PICA occlusion.

Q: Which of the following is not useful for the diagnosis of myasthenia gravis?

Voltage-gated calcium channel antibodies. ### Explanation **Myasthenia Gravis (MG)** is an autoimmune disorder of the neuromuscular junction (NMJ) characterized by muscle weakness and fatigability. The diagnosis relies on demonstrating the presence of specific autoantibodies or physiological responses at the postsynaptic membrane. **Why Voltage-gated calcium channel (VGCC) antibodies is the correct answer:** VGCC antibodies are the hallmark of **Lambert-Eaton Myasthenic Syndrome (LEMS)**, not Myasthenia Gravis [1]. In LEMS, antibodies attack the *presynaptic* calcium channels, preventing the release of acetylcholine [3]. In contrast, MG is a *postsynaptic* disorder [2]. **Analysis of other options:** * **AChR antibodies:** These are the most specific markers for MG, found in approximately 85% of patients with generalized MG and 50% with ocular MG. * **Muscle-specific kinase (MuSK) antibodies:** These are found in about 30–40% of patients who are "seronegative" for AChR antibodies. * **Edrophonium (Tensilon) test:** This is a pharmacological test using a short-acting acetylcholinesterase inhibitor. A rapid, transient improvement in muscle strength (e.g., resolution of ptosis) is diagnostic of MG [1]. --- ### High-Yield Clinical Pearls for NEET-PG: * **Most Sensitive Test:** Single-fiber Electromyography (SFEMG) showing increased "jitter." * **Initial Screening Test:** AChR antibody titer (highly specific). * **Bedside Test:** Ice pack test (improvement of ptosis due to cold inhibiting acetylcholinesterase). * **Associated Pathology:** Thymoma (found in 10–15% of MG patients); a CT chest is mandatory in all newly diagnosed cases [1]. * **Treatment of Choice:** Pyridostigmine (first-line) and Thymectomy (indicated in most patients aged 15–60) [1].

Question 1

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 2

Which of the following increases the risk of Parkinsonism?

Accepted Answer

Nicotine

Answer

MPTP

Answer

Parkin gene

Answer

Head injury

Question 3

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 4

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

Question 5

A patient presents with the CT finding shown in the image. Which one of the following signs is this finding most likely to produce?

Accepted Answer

Hemiplegia

Answer

Uniocular blindness

Answer

Alexia without agraphia

Answer

Hemiballismus

Question 6

Which of the following conditions has the least chance of causing seizures?

Accepted Answer

HIV encephalopathy

Answer

Hypoglycemia

Answer

Hypocalcemia

Answer

Neurocysticercosis

Question 7

Unilateral stepping gait is seen in all except?

Accepted Answer

Distal polyneuropathy

Answer

L5 radiculopathy

Answer

Sciatic neuropathy

Answer

Peroneal neuropathy

Question 8

Which of the following can cause 3rd nerve paralysis?

Accepted Answer

Midbrain infarct

Answer

Posterior communicating artery (PCA) aneurysm

Answer

Tolosa-Hunt syndrome

Answer

Lateral medullary lesions

Question 9

Lateral medullary syndrome (Wallenberg syndrome) is characterized by all features EXCEPT:

Accepted Answer

Horner's syndrome is rare

Answer

Giddiness

Answer

Dysphagia

Answer

Crossed hemianaesthesia

Question 10

Which of the following is not useful for the diagnosis of myasthenia gravis?

Accepted Answer

Voltage-gated calcium channel antibodies

Answer

AChR antibodies

Answer

Muscle-specific kinase antibodies

Answer

Edrophonium test

Neurology — MCQs

Neurology — MCQs

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