Velocity storage in labyrinthine disorders.

We studied 13 patients with unilateral peripheral vestibular lesions following removal of acoustic neurinomas. The time constant of the VOR after surgery was 6.4 +/- 2.6 seconds (normal is 18.5 +/- 7.7 seconds). The time constant of OKAN after surgery was 7.2 +/- 1.8 seconds (normal is 11.3 +/- 3.2 seconds). The mean initial velocity of OKAN after surgery was 9.7 +/- 2.4 deg/second (normal is 11.7 +/- 5.9 deg/second). These data suggest that unilateral peripheral vestibular loss is associated with a complete loss of velocity storage for canal input but only a partial loss of velocity storage for visual input. These results can be accounted for by current mathematical models of the velocity storage mechanism.