A patient exhibits an acute onset of right-sided ptosis, miosis, and anhidrosis.
Which neuroanatomical pathway is most likely disrupted?
A. Sympathetic pathway at the level of the superior cervical ganglion
B. Parasympathetic fibers from the Edinger-Westphal nucleus
C. Central sympathetic tract from the hypothalamus to the ciliospinal
center
D. Oculomotor nerve (CN III) fascicles at the midbrain
Correct Answer: A - Sympathetic pathway at the level of the
superior cervical ganglion
RATIONALE
Horner syndrome results from sympathetic disruption. Anhidrosis
helps localize: central lesions (C) often spare sweating due to
divergent pathways, while a lesion at the superior cervical ganglion
(A) affects all three signs. Parasympathetic (B) and CN III (D) lesions
cause different pupillary abnormalities (mydriasis, ptosis without
miosis).
Question 2
During a mental status exam, a patient correctly repeats three words and recalls
them after 5 minutes but cannot spell 'world' backwards or perform serial 7s.
Which cognitive domain is most specifically impaired?
A. Episodic memory
B. Attention and working memory
C. Language and semantic memory
D. Visuospatial construction
Correct Answer: B - Attention and working memory
Page 2
, RATIONALE
Serial 7s and spelling backwards test attention and working memory
(B). Recall of three words after delay assesses episodic memory (A),
which is intact. Language (C) and visuospatial (D) are not primarily
tested by these tasks.
Question 3
A patient with suspected myasthenia gravis undergoes repetitive nerve
stimulation. Which finding is most characteristic?
A. Decrement of compound muscle action potential amplitude >10%
B. Increment of amplitude with fast repetitive stimulation
C. Normal conduction velocity with prolonged distal latency
D. Conduction block in sensory nerves
Correct Answer: A - Decrement of compound muscle action
potential amplitude >10%
RATIONALE
Myasthenia gravis is a postsynaptic neuromuscular junction disorder;
repetitive nerve stimulation at 3-5 Hz shows a decremental response
>10% (A). Increment (B) is seen in Lambert-Eaton syndrome.
Conduction velocity (C) and sensory involvement (D) are not typical.
Question 4
Which cranial nerve is most directly assessed by the corneal reflex, and what is
the efferent limb?
A. Afferent: CN V1; Efferent: CN VII
B. Afferent: CN V2; Efferent: CN III
C. Afferent: CN VII; Efferent: CN V
D. Afferent: CN IX; Efferent: CN X
Correct Answer: A - Afferent: CN V1; Efferent: CN VII
Page 3
, RATIONALE
The corneal reflex afferent is the ophthalmic division of trigeminal
(CN V1), and efferent is facial nerve (CN VII) causing eye blink.
Other options misassign sensory or motor limbs (B, C, D).
Question 5
A patient presents with sudden severe headache, neck stiffness, and
photophobia. Non-contrast CT is negative. Which next step is most appropriate
according to current guidelines?
A. Lumbar puncture after 12 hours from symptom onset
B. CT angiography to rule out aneurysm
C. MRI brain with contrast
D. Empiric antibiotics and antiviral therapy
Correct Answer: A - Lumbar puncture after 12 hours from
symptom onset
RATIONALE
For suspected subarachnoid hemorrhage with negative CT, lumbar
puncture for xanthochromia is recommended, ideally after 12 hours to
avoid false negatives (A). CT angiography (B) is for aneurysm
detection but does not replace LP. MRI (C) and empiric therapy (D)
are not first-line for this presentation.
Question 6
Which assessment finding best differentiates upper motor neuron (UMN) from
lower motor neuron (LMN) lesions?
A. Hyporeflexia and fasciculations in UMN lesions
B. Hyperreflexia and spasticity in UMN lesions
C. Muscle atrophy is prominent in UMN lesions
D. Babinski sign is present in LMN lesions
Correct Answer: B - Hyperreflexia and spasticity in UMN lesions
Page 4