Fatigability of nystagmus on repeated testing most strongly suggests which type of lesion?

• A. Peripheral vestibular lesion
• B. Central nervous system lesion
• C. Cochlear pathology
• D. Visual impairment

Answer: (A)

Fatigability of nystagmus on repeated testing points to a peripheral vestibular lesion. When the vestibular input comes from a damaged peripheral organ or nerve, sustained or repeated stimulation tends to produce a diminishing, tired-looking nystagmus as the peripheral drive fatigues. Central sources of nystagmus, by contrast, often show persistence, direction changes with gaze, or vertical components that don’t easily fatigue with repetition, because they reflect brainstem or cerebellar processing abnormalities rather than a fatigable peripheral signal. Cochlear pathology and visual impairment don’t typically produce this fatigable vestibular nystagmus pattern, since they affect hearing or visual-oculomotor function rather than the peripheral vestibular input that drives fatigable nystagmus.