Evaluation of the galvanic vestibulo-ocular response recorded with a modified electronystagmographic technique.

Previously, a simple method for recording galvanic nystagmus (GN) using conventional electronystagmography (ENG) was demonstrated. The present study reports on investigations made to examine the applicability of that technique. During a standard stimulus over 20 s, amplitudes and rate of saccades show no tendency to diminish. In a series of 10 repeated standard stimuli over 16 min, a parabolic relationship is observed between time on one side and on the other, the mean amplitude, the mean rate of saccades and the sum of amplitudes per stimulus duration. The threshold of GN was 1.29 mA and that of induced tilting sensation 3.64 mA. In a series of 8 repeated threshold stimuli, thresholds of GN and tilting sensation linearly increase (p less than 0.001). During the slow increase of the current, the amplitudes and frequency of saccades and the slow-phase velocity linearly increase (p less than 0.01). The direction of per- and poststimulatory galvanic nystagmus and tilting sensation were investigated. Several autonomic reactions and psychophysical sensations during stimulation were noted. In conclusion, it is thought that the modified ENG technique is a valid method for further clinical use and basic research and its applicability has proven to be good.