Normative data for P1/N1-latencies of vestibular evoked myogenic potentials induced by air- or bone-conducted tone bursts.

OBJECTIVE: The response characteristics of acoustically elicited vestibular evoked myogenic potentials (VEMPs) largely depend on the stimuli applied. A tone-burst stimulation of 500 Hz seems to be clinically most appropriate because those VEMPs can be elicited at the lowest stimulus intensity possible. The aim of the present paper was to describe normative data for tone-burst evoked VEMPs. METHODS: VEMPs of 64 healthy subjects were recorded ipsilaterally during air- or bone-conducted tone burst stimulation. The EMG of the tonically activated sternocleidomastoid muscle was recorded ipsilaterally by surface electrodes. Averages were taken for P1/N1-latencies and -amplitudes of male and female volunteers within 3 different age groups. RESULTS: The latencies did not show any significant differences between female and male volunteers or between air- and bone-conducted stimulation. The latencies did also not show any significant difference among the 3 age groups. The limits for normal latencies (mean + 2 SD) are, therefore, 20.3 ms for P1 and 28.0 ms for N1. Although the P1/N1-amplitudes were decreased with increasing age, the tonic muscle activity was not significantly different between the age groups. CONCLUSIONS: The present findings strongly suggest the evaluation of VEMP latencies by using normative values obtained exactly with the same stimulus parameters. SIGNIFICANCE: Normative data as described in the present study are required to detect isolated saccular defects which are indicative of a vestibular disorder.