During videonystagmography (VNG) caloric testing, a 'directional preponderance' to the right (using Jongkees formula) indicates:
- A Right labyrinthine weakness
- B A tendency for nystagmus to beat rightward regardless of which ear is irrigated — suggesting irritative right-sided lesion or contralateral lesion ✓
- C Left labyrinthine weakness
- D Bilateral vestibular areflexia
Correct answer: B. A tendency for nystagmus to beat rightward regardless of which ear is irrigated — suggesting irritative right-sided lesion or contralateral lesion
Explanation
Jongkees formula calculates two parameters: canal paresis (CP — reduced response of one labyrinth) and directional preponderance (DP — asymmetry between right-beating and left-beating nystagmus totals). A rightward DP means right-beating nystagmus is stronger overall, suggesting either an irritative right-sided lesion (early Meniere's, recovery phase of right vestibular neuritis) or inhibitory left-sided lesion — it reflects a spontaneous nystagmus tendency rather than a fixed labyrinthine weakness. CP >25% and DP >30% are considered significant.
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.