Development of high frequency vestibulo-ocular responses to active head shaking.

Computer aided active head shaking test has several advantages because it can be used clinical at frequencies higher than 2 Hz. In this study, VOR gain and phase were examined over age. For this experiment, we designed an original measurement system composed of EOG, an angular velocity sensor and a microcomputer. VOR gain was expressed by transfer function. Forty normal subjects ranging from 10 to 75 were examined for high frequency VOR responses to active head shaking. VOR gain at frequencies higher than 2 Hz attained the same value as that seen in children below the age of 10 years. The VOR gain was nearly 1 within 2 Hz, decreasing with frequencies above 4 Hz. The effect of aging was shown at frequencies of more than 4 Hz, and appeared in patients above 50 years of age. No obvious phase lag was observed within 5 Hz.