Fig. 2.

Head and eye velocity traces in response to passive head movements in the plane of the horizontal semicircular canal for 2 patients before and after gentamicin treatment, patient X (a–c) and patient Y (d–f). Pre-gentamicin traces (a, d), early post-gentamicin traces (b, e), and late post-gentamicin traces (c, f) are shown. Gray traces represent head velocity and black traces represent the corresponding eye velocity; horizontal canal AVOR gain value was calculated as the ratio of eye velocity to head velocity and is noted in the upper right corner. Vertigo rate is noted in the lower left corner of each panel. Note that sudden increases in eye velocity occurring >70 ms after onset of head movement correspond to refixation saccades. The gain calculations were done on data prior to the appearance of these refixation saccades to ensure that only vestibularly-driven eye movements were considered.