Cervical Vestibular-Evoked Myogenic Potentials in Normal Subjects
Introduction: The Cervical Vestibular-Evoked Myogenic Potentials tests the vestibulo-cervical reflex looking for dysfunctions at the saccule and/or inferior vestibular nerve.
Objective: The study aims to establish the normal range of the responses P13 and N23.
Method: Thirty-five normal subjects aged 31 to 92 years(mean 53), 17 men and 18 women, took part of 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: 115.60 uV (±40.35), left: 113.07 uV (±45.70); asymmetry 9% (±5.90); latency P13 right: 16.70 ms (0.94) and left: 16.60 ms (±0.88), latency of N23 right: 24.90 ms (±1.49), and left: 24.50 ms (±1.57).
Conclusion: Using the above-described protocol is to be considered normal. The difference in amplitude of N10P15 is up to 35% between one and the other side (mean + 3 standard deviation). The latency of P13 is up to 18.45 ms, of N23 up to 27.75 ms; the difference between P13 latencies is up to 1.30 ms and between N23 latencies up to 3.18 ms (mean + 2 standard deviation).