ABPN Neurological Examination and Conditions 2 — Questions and Answers
Question 1: A patient cannot abduct the eye on the affected side and reports horizontal diplopia worse at distance. Which cranial nerve is most likely affected?
- Oculomotor (CN III)
- Trochlear (CN IV)
- Abducens (CN VI) (Correct answer)
- Optic (CN II)
Correct answer: Abducens (CN VI)
CN VI innervates the lateral rectus, so its palsy impairs eye abduction and causes horizontal diplopia.
Question 2: A positive Romberg sign indicates a deficit primarily in which system?
- Cerebellar coordination
- Proprioceptive/dorsal column pathways (Correct answer)
- Corticospinal motor tract
- Vestibular canal function only
Correct answer: Proprioceptive/dorsal column pathways
Romberg is positive when standing balance worsens with eyes closed, indicating loss of proprioceptive input via the dorsal columns.
Question 3: The plantar (Babinski) reflex is considered pathological in an adult when the great toe does what?
- Flexes downward
- Extends upward (dorsiflexes) (Correct answer)
- Does not move
- Curls medially
Correct answer: Extends upward (dorsiflexes)
An upgoing great toe on plantar stimulation indicates an upper motor neuron lesion.
Question 4: Which finding best distinguishes an upper motor neuron lesion from a lower motor neuron lesion?
- Fasciculations and atrophy
- Hyperreflexia and spasticity (Correct answer)
- Flaccid paralysis
- Absent reflexes
Correct answer: Hyperreflexia and spasticity
Upper motor neuron lesions typically cause spasticity and hyperreflexia, whereas lower motor neuron lesions cause flaccidity and hyporeflexia.
Question 5: A patient with resting tremor, bradykinesia, and cogwheel rigidity most likely has dysfunction of which structure?
- Cerebellum
- Substantia nigra (Correct answer)
- Hippocampus
- Broca's area
Correct answer: Substantia nigra
Loss of dopaminergic neurons in the substantia nigra causes the classic parkinsonian triad.
Question 6: Testing the corneal reflex primarily assesses which two cranial nerves?
- CN II and III
- CN V and VII (Correct answer)
- CN IX and X
- CN VII and VIII
Correct answer: CN V and VII
The afferent limb is the trigeminal nerve (V1) and the efferent limb is the facial nerve (blink).
Question 7: Pronator drift, where one arm slowly pronates and drifts downward with eyes closed, indicates a lesion of which tract?
- Spinothalamic tract
- Dorsal column
- Contralateral corticospinal tract (Correct answer)
- Spinocerebellar tract
Correct answer: Contralateral corticospinal tract
Pronator drift is a subtle sign of upper motor neuron weakness from a contralateral corticospinal tract lesion.
ABPN Neurological Examination and Conditions 2
A patient cannot abduct the eye on the affected side and reports horizontal diplopia worse at distance.
Which cranial nerve is most likely affected?