Which single clinical feature most strongly favours a CENTRAL cause of nystagmus over a peripheral vestibular cause?

• A Nystagmus that is inhibited when the patient fixates on a stationary target
• B Nystagmus that obeys Alexander's law, increasing in amplitude with gaze toward the fast phase
• C Associated nausea and vomiting
• D Failure of visual fixation to suppress the nystagmus ✓

Explanation

Peripheral vestibular nystagmus arises from an imbalance in vestibular tone and is normally suppressed by visual fixation, since the smooth pursuit system can compensate for a stable peripheral deficit. Central nystagmus originates within brainstem or cerebellar circuits that themselves generate the oscillation, so fixation fails to dampen it and may even accentuate it. Alexander's law applies to peripheral nystagmus, prominent vegetative symptoms favour a peripheral lesion, and fixation suppression argues for peripheral, not central, origin.

Reference: Dhingra, Diseases of Ear, Nose and Throat, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.