Comparison of horizontal nystagmus in different head positions: a study by damped pendular rotation test

Damped pendular rotation was given with the initial maximum speed of 180 degrees/s. The subject's head was tilted forward at an angle of 30 degrees from the upright position, or kept in the upright position, or tilted backward at 30 degrees from the upright position. Electronystagmography was used to evaluate the maximal slow-phase eye velocity (mx SPEV) of the horizontal nystagmus. Differences existed in mx SPEVs of the horizontal nystagmus for the head-tilted positions at 30 degrees forward or backward and that obtained in the upright position. The mx SPEV of the horizontal nystagmus in the upright position was higher than those acquired in the head-tilted positions.