SPEX Neurology 4 — Questions and Answers
Question 1: A patient presents with pill-rolling tremor at rest, cogwheel rigidity, and bradykinesia. Which area of the brain is most affected?
- Cerebellum
- Basal ganglia (Correct answer)
- Frontal cortex
- Hippocampus
Correct answer: Basal ganglia
The cardinal features of Parkinsonism result from dopamine depletion in the basal ganglia, specifically the substantia nigra.
Question 2: Which cranial nerve is responsible for the corneal reflex (afferent limb)?
- CN VII
- CN III
- CN V (ophthalmic branch) (Correct answer)
- CN IV
Correct answer: CN V (ophthalmic branch)
The afferent limb of the corneal reflex is carried by the ophthalmic branch (V1) of the trigeminal nerve (CN V); the efferent limb is CN VII.
Question 3: A 55-year-old presents with progressive proximal muscle weakness without sensory loss. CK is markedly elevated. What is the most likely diagnosis?
- Polymyositis (Correct answer)
- Myasthenia gravis
- Amyotrophic lateral sclerosis
- Lambert-Eaton syndrome
Correct answer: Polymyositis
Polymyositis causes proximal muscle weakness with elevated CK and is an inflammatory myopathy without sensory involvement.
Question 4: In myasthenia gravis, repetitive nerve stimulation typically shows which pattern?
- Incremental response
- Decremental response (Correct answer)
- No change
- Random variation
Correct answer: Decremental response
Repetitive nerve stimulation in myasthenia gravis shows a decremental response in compound muscle action potential amplitude due to depletion of available acetylcholine.
Question 5: A patient with a pontine lesion presents with ipsilateral facial weakness and contralateral hemiplegia. What is this pattern called?
- Wallenberg syndrome
- Weber syndrome
- Millard-Gubler syndrome (Correct answer)
- Locked-in syndrome
Correct answer: Millard-Gubler syndrome
Millard-Gubler syndrome results from a ventral pontine lesion causing ipsilateral CN VI/VII palsies and contralateral hemiplegia.
Question 6: Which of the following best describes the mechanism of action of phenytoin?
- Enhances GABA-A receptor activity
- Blocks sodium channels in their inactivated state (Correct answer)
- Inhibits calcium T-type channels
- Blocks NMDA receptors
Correct answer: Blocks sodium channels in their inactivated state
Phenytoin stabilizes neuronal membranes by blocking voltage-gated sodium channels in their inactivated state, preventing repetitive firing.
Question 7: A 68-year-old develops sudden onset vertigo, ipsilateral facial numbness, dysphagia, and contralateral loss of pain/temperature in the limbs. Which artery is affected?
- Anterior cerebral artery
- Posterior inferior cerebellar artery (Correct answer)
- Middle cerebral artery
- Basilar artery
Correct answer: Posterior inferior cerebellar artery
Posterior inferior cerebellar artery (PICA) occlusion causes Wallenberg (lateral medullary) syndrome with the described crossed findings.
SPEX Neurology 4
A patient presents with pill-rolling tremor at rest, cogwheel rigidity, and bradykinesia.
Which area of the brain is most affected?