OSCE Neurological Assessment 4 — Questions and Answers
Question 1: A patient with diabetes presents with unilateral ptosis and diplopia but a normally reactive pupil. Which condition is most likely?
- Posterior communicating artery aneurysm
- Diabetic CN III palsy (ischemic) (Correct answer)
- Horner syndrome
- Myasthenia gravis
Correct answer: Diabetic CN III palsy (ischemic)
Diabetic (ischemic) CN III palsy characteristically spares the pupil because the outer parasympathetic fibers are preserved, unlike compressive lesions such as aneurysms which compress these fibers first.
Question 2: During assessment of gait, a patient walks with wide-based, unsteady steps resembling intoxication with feet apart. This pattern is characteristic of:
- Spastic gait
- Cerebellar (ataxic) gait (Correct answer)
- Steppage gait
- Festinating gait
Correct answer: Cerebellar (ataxic) gait
Cerebellar ataxia produces a wide-based, lurching gait because the cerebellum coordinates balance and movement; patients widen their stance to maintain stability.
Question 3: A patient can feel light touch but not vibration or joint position sense in the lower extremities bilaterally. The lesion most likely affects:
- Spinothalamic tracts
- Posterior columns (dorsal columns) (Correct answer)
- Anterior horn cells
- Lateral corticospinal tracts
Correct answer: Posterior columns (dorsal columns)
Vibration and proprioception travel in the posterior (dorsal) columns; selective loss of these modalities with preserved light touch indicates posterior column disease (e.g., B12 deficiency, tabes dorsalis).
Question 4: When testing visual acuity with a Snellen chart, a patient reads the 20/200 line correctly with the right eye but no lower. This means:
- Normal vision in that eye
- The patient can read at 20 feet what a normal eye sees at 200 feet (Correct answer)
- The patient can only see at 200 feet what normal eyes see at 20 feet
- There is a refractive error that requires no further investigation
Correct answer: The patient can read at 20 feet what a normal eye sees at 200 feet
20/200 means the patient must be at 20 feet to read a letter that a person with normal vision can read at 200 feet, indicating severe visual impairment.
Question 5: Which cranial nerve is tested by asking a patient to shrug their shoulders against resistance?
- CN IX (glossopharyngeal)
- CN X (vagus)
- CN XI (accessory) (Correct answer)
- CN XII (hypoglossal)
Correct answer: CN XI (accessory)
CN XI (spinal accessory nerve) innervates the sternocleidomastoid and trapezius muscles; shoulder shrug against resistance specifically tests trapezius function.
Question 6: A patient shows cogwheel rigidity and a resting tremor that disappears with intentional movement. These findings are most associated with:
- Upper motor neuron lesion
- Cerebellar disease
- Basal ganglia dysfunction (Parkinsonism) (Correct answer)
- Peripheral neuropathy
Correct answer: Basal ganglia dysfunction (Parkinsonism)
Cogwheel rigidity and resting tremor ('pill-rolling') that diminishes with voluntary movement are cardinal features of basal ganglia dysfunction as seen in Parkinson's disease.
Question 7: When assessing for dysdiadochokinesia, which task do you ask the patient to perform?
- Walk heel-to-toe in a straight line
- Rapidly alternate hand pronation and supination on the thigh (Correct answer)
- Stand on one foot with eyes closed
- Draw a clock face from memory
Correct answer: Rapidly alternate hand pronation and supination on the thigh
Dysdiadochokinesia (impaired rapid alternating movements) is assessed by asking the patient to rapidly pronate and supinate one hand on the thigh; irregularity indicates cerebellar dysfunction.
OSCE Neurological Assessment 4
A patient with diabetes presents with unilateral ptosis and diplopia but a normally reactive pupil.
Which condition is most likely?