The normal values of ocular vestibular evoked myogenic potantials in the healthy adult population

Stimulants such as high-level voice and vibration may initiate reflex ocular movements without head movement. Ocular vestibular evoked myogenic potential test is a recently introduced noninvasive test that evaluates ascending vestibular tract and vestibulo-ocular reflex that is crossed in the brain stem. The aim of this study is to determine the normal values of ocular vestibular evoked myogenic potentials in the healthy adult population.The study was carried out with 38 healthy volunteers with no ear complaints, in Baskent University, Department of Otorhinolaryngology. Audiological evaluation and positional tests were applied to the subjects after a thorough otorhinolaryngologic examination. The patients that had pure tone average of lower than 20 dB and that have no nystagmus during the positional tests were involved. Ocular vestibular evoked myogenic potential tests were performed and the latency and amplitude values of the waves were recorded.Eighteen of the 38 patients (76 ears) were male and the mean age of the patients was 40,2±11,6 (22-58). N1 latency was 9,8±2,1 msec for the right ear and 9,3±1,9 msec for the left ear (p=0,312). P1 was 15,0±2,3 msec in the right ear and 14,7±2,2 msec in the left (p= 0,651). Amplitude values were found as 3,3±1,5 µV in the right ear and 3,3±1,1 µV in the left ear (p= 0,919). There was no significant difference of latency and amplitude values between male and female patients (p>0,05). There was a positive correlation of N1 values and age (r=242, p =0,0359). Similarly, there was a positive correlation of P1 values and age (r=250, p=0,030). No relationship was found between age and amplitude (r=052, p=0,633). Test parameters of 76 ears were calculated since age and side did not interfere with the test results. Thus, N1 latency was 9,62±2,02 (4,30-16,00) msec; P1 latency was 14,90 ±2,33 (9,0-21,00) msec and the mean amplitude was found as 3,36 ±1,36 (1,06-8,48) µV.The latency values of ocular vestibular evoked myogenic potentials were found consistent with the values in the literature. The results were considered as the normative values of adult population in our clinic, which will be used in evaluation of vestibular disorders.Key words: Vestibulo-ocular reflex, ocular vestibular myogenic response, normative data