Neurotology: Central vs Peripheral Vestibular Localization
Core concepts
The neurotology candidate must separate peripheral (labyrinth, vestibular nerve) from central (brainstem, cerebellum, cortex) disease using the pattern of nystagmus, the head impulse test, skew deviation, and the presence or absence of auditory symptoms. Understand the vestibulo-ocular reflex arc: horizontal canal to medial vestibular nucleus to abducens and oculomotor nuclei. Know that peripheral lesions produce unidirectional horizontal-torsional nystagmus that suppresses with fixation and beats away from the lesioned side, whereas central lesions produce direction-changing or purely vertical/torsional nystagmus that does not suppress. Recognize the HINTS battery: head impulse, nystagmus type, test of skew.
Traps in questions
- A normal head impulse in an acutely vertiginous patient points away from peripheral disease, not toward it.
- Skew deviation is a central sign; vertical misalignment is a brainstem/cerebellar finding.
- Purely vertical or bidirectional nystagmus is never peripheral.
- Sudden hearing loss accompanying vertigo favors a peripheral labyrinthine cause (e.g., labyrinthitis), but posterior circulation stroke can mimic this; do not anchor on age or vascular risk factors alone.
- Direction of nystagmus is named for its fast phase.
Worked rule of thumb
In acute vestibular syndrome with vertical nystagmus, skew deviation, or a normal head impulse, treat as central until imaging and exam exclude stroke, even if the patient has nausea and hearing complaints. Conversely, unidirectional horizontal nystagmus with an abnormal head impulse and no skew strongly supports a peripheral cause.