On videonystagmography (VNG), a patient shows spontaneous nystagmus that increases in darkness, direction-fixed, and normal caloric responses bilaterally. This pattern is most consistent with:

• A Central (brainstem/cerebellar) pathology ✓
• B Unilateral peripheral vestibular loss (compensated)
• C Acute vestibular neuritis on the left
• D Benign paroxysmal positional vertigo (BPPV)

Explanation

Spontaneous nystagmus that increases in darkness (reduced visual fixation suppression) and is direction-fixed without corresponding unilateral caloric asymmetry suggests a central origin. Peripheral vestibular nystagmus is typically suppressed by visual fixation. Normal bilaterally equal caloric responses rule out unilateral peripheral loss. Central causes include cerebellar or brainstem lesions. Acute vestibular neuritis would show a clearly unilateral caloric weakness. BPPV nystagmus is position-dependent, not spontaneous.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.