Persistent otolith dysfunction even after successful repositioning in benign paroxysmal positional vertigo

To evaluate utricular and saccular function during the acute and resolved phases of BPPV, ocular and cervical vestibular evoked myogenic potentials (VEMPs) were studied in 112 patients with BPPV and 50 normal controls in a referral-based University Hospital. Ocular (oVEMPs) and cervical VEMPs (cVEMPs) were induced using air-conducted sound (1000 Hz tone burst, 100 dB normal hearing level) at the time of initial diagnosis and 2 months after successful repositioning in patients with BPPV, and the results were compared with those of the controls. Abnormalities of cVEMPs and oVEMPs in patients with BPPV were prevalent and significantly higher compare to the healthy control group (p < 0.01 in each VEMP by chi-square test). In the patient group, difference between the proportions of abnormal responses of cVEMP and oVEMP was not significant in both affected (p = 0.37, chi-squared test) and non-affected (p = 1.00) ears. The abnormalities were more likely reduced or absent responses rather than delayed ones; reduced or absent responses are 17.6% in cVEMPs (p = 0.04, chi-square) and 21.6% in oVEMPs (p < 0.01). The non-affected ear in the BPPV group also showed significantly higher abnormalities of cVEMP and oVEMP when compared to the control group. The follow-up VEMPs after repositioning maneuvers were not significantly different compared to the initial values from both stimulated affected and non-affected ears. Although most patients had unilateral BPPV, bilateral otolithic dysfunction was often shown by persistently reduced or absent cervical and ocular VEMPs, suggesting that BPPV may be caused by significant bilateral damage to the otolith organs.