Abstract
To evaluate the function of the phase on the vestibulo-ocular reflex (VOR) with sinusoidal rotation tests, we assessed young, healthy volunteers, patients with canal paresis (CP), benign paroxysmal positional vertigo (BPPV), and acoustic neurinomas (ATs). For the control condition, subjects, with their eyes open, were sinusoidally rotated in complete darkness at a frequency of 0.4 and 0.8Hz with a maximum angular velocity of 60°/s for 30 seconds. Sinusoidal tests were performed at earth vertical axis rotation (EVAR) and 30° nose-up, off-vertical axis rotation (OVAR). We observed a significant phase delay at 0.8Hz EVAR on the unilateral CP patients vs controls, and 0.4Hz OVAR on the AT patients vs controls. On BPPV patients, we found a significant phase lead at 0.8Hz OVAR compared to EVAR, which was not observed after recovery of the BPPV: these responses consisted in a reduction of the VOR gain on BPPV. We propose that evaluating the VOR phase is one useful way to understand the vestibular function.
