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

Influence of head position on the vestibulo-ocular reflex during rotational testing

The influence of two static head positions on the horizontal nystagmus induced by sinusoidal rotational stimulation in a group of 24 healthy subjects was investigated. The rotation test was performed with the subject's head in the primary position (upright) and with the head 30 degree pitched down. Computerized electronystagmography was used to measure the maximum slow component velocity of the horizontal nystagmus and to calculate gain, phase and asymmetry. The vestibulo-ocular reflex (VOR) gain obtained during rotation with the head in the primary position was significantly higher than with the head bent 30 degree forward. No other significant differences were found.