Upright positioning-related reverse nystagmus in posterior canal benign paroxysmal positional vertigo and its effect on prognosis

BACKGROUND: Positional nystagmus elicited by the Dix-Hallpike maneuver often reverses its direction as the patient is re-seated from the provoking head hanging position. The incidence of reverse nystagmus and its association with prognosis in posterior canal benign paroxysmal positional vertigo (pcBPPV) is not clear. OBJECTIVE: To determine the incidence of upright positioning-related reverse nystagmus and its association with the success of canalith repositioning (Epley) maneuver (CRM) treatment in pcBPPV. METHODS: The records of patients that had been tested with video-nystagmography in a tertiary care center, between October 2016 and March 2019, were reviewed. Data were obtained from detailed analysis of video recordings of 321 patients with typical pcBPPV. RESULTS: Reverse nystagmus was determined in 85% of the patients with pcBPPV. The number of CRMs required for treatment was lower in patients with reverse nystagmus (1.32±0.68) compared to patients without reverse nystagmus (1.81±0.98) (p < 0.001). There was not a statistically significant relationship between reverse nystagmus and recurrence (p = 0.623). CONCLUSIONS: The absence of reverse nystagmus on upright positioning during the Dix-Hallpike test predicts poor success for the CRM, as repetitive repositioning maneuvers might be required to achieve successful treatment in pcBPPV.