Effect of click duration on vestibular-evoked myogenic potentials.

CONCLUSIONS

The 0.5-VEMP demonstrated a more prominent waveform morphology than either the 0.1- or 0.2-VEMPs. In addition, the 0.5-VEMP had smaller interaural latency differences than the 1.0-VEMP. These findings suggest that 0.5 ms is superior to other click durations in terms of yielding VEMP responses for clinical use.

OBJECTIVE

In order to establish the ideal stimulus condition for vestibular-evoked myogenic potentials (VEMPs), we studied the use of various click durations to generate different response patterns in normal subjects. The influence of click durations on VEMPs is described and the optimal stimulation duration for clinical use is suggested.

MATERIAL AND METHODS

This was a prospective study. Eighteen healthy volunteers (36 ears) underwent VEMP tests. Four click durations (0.1, 0.2, 0.5 and 1.0 ms) were used in a random order to elicit VEMP responses (0.1-, 0.2-, 0.5- and 1.0-VEMP, respectively). The latency of each peak (p13, n23), the peak-to-peak interval and amplitude (p 13-n23) and the relative amplitude (defined as the amplitude divided by that of the 0.5-VEMP) were measured and compared.

RESULTS

Click stimulation of 34 ears (94%) produced 0.1-VEMP responses, whereas positive 0.2-, 0.5- and 1.0-VEMP responses were observed in 36 (100%). The latencies of peaks p13 and n23 were significantly prolonged between successive stimulus durations from 0.1 to 1.0 ms (p <0.05), in contrast to the p13-n23 intervals (p >0.05). The 1.0-VEMP displayed the largest SDs of latencies and interval among the four different VEMPs. The relative amplitude was significantly increased between successive durations from 0.1 to 0.5 ms (alphaT <0.05), but there was no significant difference between 0.5 and 1.0 ms (alphaT >0.05).