Neurology Practice Questions

Q: A patient presents with a right homonymous hemianopia, characterized by saccadic pursuit movements and defective optokinetic nystagmus. Where is the lesion most likely located?

Parietal lobe. ### Explanation The correct answer is **Parietal lobe**. This question tests the localization of visual pathway lesions based on associated neurological signs. #### 1. Why the Parietal Lobe is Correct A lesion in the parietal lobe involves the **optic radiations** (superior fibers), resulting in a **contralateral homonymous hemianopia** (classically denser inferiorly). * **Optokinetic Nystagmus (OKN):** The parietal lobe is the center for the "slow phase" of pursuit. A lesion here disrupts the smooth pursuit toward the side of the lesion, leading to a **defective OKN** (specifically, a decreased response when the drum is rotated toward the side of the lesion). * **Saccadic Pursuit:** Because smooth pursuit is impaired, the eyes use "catch-up" saccades to follow a moving object, resulting in jerky or **saccadic pursuit movements**. #### 2. Why Other Options are Incorrect * **Frontal Lobe:** This contains the Frontal Eye Fields (FEF), which control **saccades** to the opposite side. Lesions here cause a gaze deviation toward the side of the lesion but do not typically cause homonymous hemianopia. * **Occipital Lobe:** While this is the most common site for homonymous hemianopia (often macula-sparing), **OKN remains normal** because the parietal pursuit pathways are intact. * **Temporal Lobe:** Lesions here involve Meyer’s loop, causing a **"pie in the sky"** (superior quadrantanopia). OKN is typically normal in temporal lobe lesions. #### Clinical Pearls for NEET-PG * **Parietal Lesion:** "Pie on the floor" (Inferior quadrantanopia) + Abnormal OKN. * **Temporal Lesion:** "Pie in the sky" (Superior quadrantanopia) + Normal OKN. * **Cogan’s Rule:** An asymmetric OKN response in a patient with homonymous hemianopia strongly localizes the lesion to the **parietal lobe**. * **Macular Sparing:** Highly suggestive of a **vascular occipital lobe** lesion (due to dual blood supply from MCA and PCA).

Q: Which of the following conditions typically spares the pupil?

Myasthenia gravis. **Explanation:** The correct answer is **Myasthenia Gravis (MG)**. **1. Why Myasthenia Gravis is the correct answer:** Myasthenia Gravis is an autoimmune disorder caused by antibodies against the **nicotinic acetylcholine receptors (nAChR)** at the neuromuscular junction of **striated (skeletal) muscles**. The intraocular muscles (sphincter pupillae and ciliary muscle) are **smooth muscles** controlled by **muscarinic receptors**. Therefore, MG characteristically involves the levator palpebrae superioris (causing ptosis) and extraocular muscles (causing diplopia) but **never affects the pupil or accommodation.** **2. Analysis of Incorrect Options:** * **Riley-Day Syndrome (Familial Dysautonomia):** This is a multisystem autonomic neuropathy. It features a **parasympathetic denervation supersensitivity** of the pupil; patients typically show a constricted pupil that reacts excessively to dilute pilocarpine. * **Disseminated Sclerosis (Multiple Sclerosis):** MS frequently causes **Optic Neuritis**. This leads to an afferent pupillary conduction defect, clinically manifesting as a **Relative Afferent Pupillary Defect (RAPD)** or Marcus Gunn pupil. * **Horner’s Syndrome:** This is caused by a lesion in the sympathetic pathway. It directly involves the pupil, resulting in **miosis** (due to unopposed parasympathetic action) along with ptosis and anhidrosis. **Clinical Pearls for NEET-PG:** * **Rule of Thumb:** If a patient has ptosis and diplopia but the **pupil is normal**, think of **Myasthenia Gravis** or a **Pupil-sparing Third Nerve Palsy** (often diabetic/ischemic). * **Cogan’s Lid Twitch:** A classic sign of MG where the upper eyelid overshoots when the patient shifts gaze from down to primary position. * **Ice Pack Test:** A bedside test for MG; cold temperatures improve neuromuscular transmission, temporarily resolving ptosis.

Q: A 60-year-old man with progressive dementia of recent onset presents with intermittent irregular jerky movements. EEG shows periodic sharp biphasic waves. What is the most likely diagnosis?

Creutzfeldt Jakob disease. **Explanation:** The clinical presentation of **rapidly progressive dementia** associated with **myoclonus** (intermittent irregular jerky movements) and a characteristic **EEG pattern** is the classic triad for **Creutzfeldt-Jakob Disease (CJD)**, a prion-mediated neurodegenerative disorder [1] [3]. 1. **Why CJD is correct:** The hallmark of CJD is the rapid decline in cognitive function. The "jerky movements" described are **startle-induced myoclonus**. The EEG finding of **periodic synchronous sharp wave complexes (PSWCs)**, often biphasic or triphasic, occurring at a frequency of 0.5–2.0 Hz, is highly specific (approx. 90%) for sporadic CJD. 2. **Why other options are incorrect:** * **Alzheimer’s Disease:** While it causes dementia, the progression is slow (years, not months) and EEG typically shows non-specific slowing, not periodic sharp waves [2]. * **Lewy Body Dementia:** Characterized by visual hallucinations and parkinsonism. While it involves cognitive decline, the specific EEG pattern of CJD is absent. * **Herpes Simplex Encephalitis:** Presents acutely with fever, seizures, and altered sensorium. EEG typically shows Periodic Lateralized Epileptiform Discharges (**PLEDs**) localized to the **temporal lobes**, rather than generalized periodic waves. **High-Yield Pearls for NEET-PG:** * **Most sensitive MRI finding:** "Pulvinar sign" (thalamus) or "Hockey stick sign," and cortical ribboning on DWI/FLAIR sequences. * **CSF Marker:** Elevation of **14-3-3 protein** or **Tau protein**. * **Gold Standard Diagnosis:** Brain biopsy (showing spongiform vacuolation), though rarely performed. * **Definitive Test:** RT-QuIC (Real-time quaking-induced conversion) is now the preferred diagnostic test for detecting abnormal prion proteins.

Q: Which of the following is NOT a feature of an extramedullary tumor?

Sacral sparing. To differentiate between **Intramedullary** (within the spinal cord) and **Extramedullary** (outside the cord, within the dura) lesions, one must understand the somatotopic organization of the spinal cord [1]. ### Why "Sacral Sparing" is the Correct Answer **Sacral Sparing** is a hallmark of **Intramedullary lesions** (e.g., ependymoma, syringomyelia) [3]. In the spinal cord, the long tracts are organized such that the fibers for the sacral segments are located most peripherally (near the surface) [2]. * In an **intramedullary lesion**, the pressure starts from the center and moves outward; the outermost sacral fibers are the last to be affected, leading to "sacral sparing" of sensation. * In an **extramedullary lesion**, the pressure is applied from the outside [1]. Therefore, the sacral fibers are compressed **first**, and sacral sparing is **absent**. ### Explanation of Incorrect Options * **A. Early corticospinal signs:** Extramedullary tumors (like meningiomas or schwannomas) compress the cord from the outside, quickly involving the corticospinal tracts [1]. This leads to early spasticity and weakness. * **B. Root pain or midline back pain:** This is a classic early feature of extramedullary tumors [1]. As the tumor grows, it frequently compresses dorsal nerve roots (causing radicular pain) or the vertebrae/dura (causing localized back pain). * **C. Abnormal CSF:** Extramedullary tumors often cause a partial or complete block of CSF flow (Froin’s Syndrome), leading to significantly elevated protein levels in the CSF. ### High-Yield Clinical Pearls for NEET-PG | Feature | Intramedullary | Extramedullary | | :--- | :--- | :--- | | **Pain** | Late and poorly localized | **Early** and radicular | | **Sensory Loss** | Dissociated (Cape-like) | Ascending (starts low, moves up) | | **Sacral Sparing** | **Present** | **Absent** | | **Trophic changes** | Common | Rare | | **Common Tumors** | Ependymoma, Glioma | Schwannoma, Meningioma |

Q: Pseudobulbar palsy is seen with which of the following conditions?

Bilateral corticobulbar lesions. **Explanation:** **Pseudobulbar palsy** is a clinical syndrome characterized by the impairment of function of cranial nerves IX, X, XI, and XII due to **Bilateral Corticobulbar tract lesions** (Upper Motor Neuron - UMN lesion). 1. **Why Option B is correct:** The motor nuclei of the lower cranial nerves (except the lower face and tongue) receive bilateral innervation from the cerebral cortex. Therefore, a unilateral lesion does not produce significant deficit. Only **bilateral lesions** of the corticobulbar tracts (located in the internal capsule or midbrain) disrupt the voluntary control of these nuclei, leading to "pseudo" (false) bulbar palsy. 2. **Why other options are incorrect:** * **Option A:** Unilateral lesions are usually compensated for by the contralateral hemisphere due to bilateral representation. * **Options C & D:** Involvement of the cranial nerve nuclei or the nerves themselves (IX, X, XII) results in **Bulbar Palsy** (Lower Motor Neuron - LMN lesion) [3], not pseudobulbar palsy [1]. **Clinical Pearls for NEET-PG:** | Feature | Bulbar Palsy (LMN) | Pseudobulbar Palsy (UMN) | | :--- | :--- | :--- | | **Site of Lesion** | Medulla (CN IX-XII nuclei/nerves) [1] | Bilateral Corticobulbar tracts | | **Tongue** | Wasted, fasciculations [3] | Spastic, "small and stiff" | | **Jaw Jerk** | Absent or Normal | **Exaggerated/Brisk** (High Yield) | | **Speech** | Nasal (Palatal palsy) | "Hot potato" or "Donald Duck" speech [2] | | **Emotions** | Normal | **Emotional Lability** (Pathological laughing/crying) | **Common Causes:** * **Pseudobulbar:** Multiple Sclerosis, Motor Neuron Disease (ALS), Bilateral strokes (Lacunar infarcts). * **Bulbar:** Guillain-Barré Syndrome, Polio, Myasthenia Gravis, Medullary tumors [1].

Question 1

What is the most common cause of embolic stroke?

Accepted Answer

Non-rheumatic atrial fibrillation

Answer

Carotid artery atherosclerosis

Answer

Paradoxical embolism

Answer

Left ventricular aneurysm

Question 2

All the following have been shown to reduce the risk of atherothrombotic stroke in primary or secondary prevention EXCEPT:

Accepted Answer

Warfarin

Answer

Aspirin

Answer

Blood pressure control

Answer

Clopidogrel

Question 3

A lesion involving the nucleus ambiguus causes a lower motor neuron lesion. How is the uvula positioned during a test for such a lesion?

Accepted Answer

It is deviated to the normal side.

Answer

It is deviated to the affected side.

Answer

It remains in the midline.

Answer

It is not used in testing.

Question 4

A patient presents with a right homonymous hemianopia, characterized by saccadic pursuit movements and defective optokinetic nystagmus. Where is the lesion most likely located?

Accepted Answer

Parietal lobe

Answer

Frontal lobe

Answer

Occipital lobe

Answer

Temporal lobe

Question 5

Which of the following conditions typically spares the pupil?

Accepted Answer

Myasthenia gravis

Answer

Riley-Day syndrome

Answer

Disseminated sclerosis

Answer

Horner's syndrome

Question 6

A 60-year-old man with progressive dementia of recent onset presents with intermittent irregular jerky movements. EEG shows periodic sharp biphasic waves. What is the most likely diagnosis?

Accepted Answer

Creutzfeldt Jakob disease

Answer

Alzheimer's disease

Answer

Lewy body dementia

Answer

Herpes simplex encephalitis

Question 7

Which of the following is NOT a feature of an extramedullary tumor?

Accepted Answer

Sacral sparing

Answer

Early corticospinal signs and paralysis

Answer

Root pain or midline back pain

Answer

Abnormal CSF

Question 8

Pseudobulbar palsy is seen with which of the following conditions?

Accepted Answer

Bilateral corticobulbar lesions

Answer

Unilateral corticobulbar lesions

Answer

Cranial nerve IX involvement

Answer

Cranial nerve XII involvement

Question 9

Which one of the following excludes a history of transient ischemic attack?

Accepted Answer

Hemorrhage

Answer

Embolic episodes

Answer

Thrombotic episodes

Answer

Complete stroke

Question 10

All of the following cause motor nerve paralysis except?

Accepted Answer

Diphtheria

Answer

Diabetes mellitus

Answer

Guillain Barre syndrome

Answer

Porphyria

Neurology — MCQs

Neurology — MCQs

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