Effects of EMG Rectification on Cervical and Ocular Vestibular Evoked Myogenic Potentials

doi:10.3969/j.issn.1672-2922.2017.02.002

Abstract：To study the influence of EMG rectification on cervical and ocular vestibular evoked myo-genic potentials, and to establish the normal range of cervical vestibular evoked myogenic potentials (cVEMP) and ocu-lar vestibular evoked myogenic potentials (oVEMP) for accurate assessment of vestibular receptor function. Twenty normal hearing adult volunteers (10 male and 10 female, 40 ears) without ear diseases, aged from 20 to 30 years (mean age=23.76 ± 2.81 years), were included in the study. cVEMPs and oVEMPs were induced using 500 Hz tone-bursts, delivered through ER-3A standard insert earphones at 100 dB nHL, while the subject assumed a sitting posi-tion. cVEMP and oVEMP responses with clear and repeatable waveforms were acquired in all subjects. The P1 and N1 latencies of cVEMPs were 14.13 ± 1.97 and 21.54 ± 2.23 ms, respectively, with an amplitude of 1.63 ± 0.60μV. oVEMP P1 and N1 latencies were 10.15±0.72 ms and 15.79±1.01 ms, respectively, with an amplitude of 1.38±1.02μV. EMG rectification of cVEMPs yielded amplitude differences of 40-50 times (P<0.05). Has a significant effect on amplitude normalization, especially for cVEMPs. Establishment of normal VEMP amplitude range with EMG rectification can improved the accuracy in the assessment of response asymmetry. The high response rate of tone-burst evoked VEMPs in a sitting position makes this test a valuable tool in vestibular evaluation, not only for assessment of utricular and saccular functions, but also for differential diagnosis.