Recovery of vestibulo-ocular reflex and gaze disturbance in patients with unilateral loss of labyrinthine function.

Vestibulo-ocular reflex (VOR) gain and the ability of gaze fixation were investigated in patients with unilateral loss of labyrinthine function during the time course of compensation (four days to 6 months). A marked directional difference in the VOR gain in the acute stage (0.51 to 0.73 at four days) decreased proportionately to the logarithm of time on rotations to the affected side and to the intact side by an increase and a slight decrease of the gain, respectively. Gaze disturbance, which occurred only on rotations to the affected side, recovered in parallel with the decrease of directional difference in the VOR gain; it was still found at 1 Hz at 6 months. Recovery of gaze disturbance in unilateral lesions seems to be accomplished not only by the change in the VOR gain, but also by intensified amplification of this gain to make up for a low VOR gain.