Ocular Vestibular-Evoked Myogenic Potentials in Normal Subjects
Introduction: The Ocular Vestibular-Evoked Myogenic Potentials test the vestibulo-ocular reflex looking for dysfunction at the utricule and/or superior vestibular nerve.
Objective: The study aims to establish the normal range of the responses N10 and P15.
Method: Thirty-one normal subjects aged from 31 to 92 years (mean 51 years), 15 male and 16 female, took part in this study. All of them were examined by ATC plus 2.2 CONTRONIC system of evoked potentials. Amplitude and latency of the peaks N10 and P15 were measured in response to 500 Hz tone burst, five cycles, Blackmann envelope, presented monoaurally 200 times (four rows of 50, summed offline), 5.1 pps, with 124 dBSPL of intensity. The responses were electrically filtered from 5 to 1,000 Hz and the time window was 50 ms.
Results: Amplitude right: 8.74 uV (±6.48), left: 9.05 uV (±6.27); asymmetry 11% (±7.98); latency N10 right: 12.25 ms (±0.73) and left: 12.30 ms (±0.55); latency of P15 right 16.84 ms (±1.12) and left: 16.20 ms (±1.82).
Conclusion: Using the described protocol is to be considered normal. The difference in amplitude of N10P15 is up to 35% between one and the other side (median ± 3 standard deviation); the latency of N10 was up to 13.56 ms, and of P15, it was up to 19.41 ms; the difference between N10 latencies is up to 1.18 ms and between P15 up to 2.50 ms (mean ± 2 standard deviation).