Characterizing the Effects of Frequency on Parameters of Short Tone-bursts Induced Ocular Vestibular Evoked Myogenic Potentials

Abstract

Stimulus is the essence of any audiovestibular investigation and ocular vestibular-evoked myogenic potential (oVEMP) would be no different. Several investigations have examined the effect of frequency of stimulus on oVEMP parameters with prime reports concentrated around amplitude and to a lesser extent threshold. Effects of stimulus frequency on latency-related parameters have been sparingly explored with equivocal results. Thus, the aim of this study was to investigate the effects of air-conducted frequency-specific short tone-bursts on latency, amplitude, and threshold-related parameters of various peaks of oVEMP. A normative study was conducted to obtain oVEMP responses from 50 healthy individuals in the age range of 18 - 30 years. Tone-bursts at octave and midoctave frequencies from 250 to 2000 Hz were used to acquire responses from the inferior oblique muscle using contralateral electrode placement. oVEMPs were present in 100% of the individuals at or below the frequency of 1000 Hz. The largest amplitudes and the lowest threshold corresponded to 500 Hz tone-burst, whereas 250 Hz produced largest absolute latencies as well as interpeak latency intervals (P < 0.05). Frequency had no effect on interaural latency difference as well as interaural amplitude ratio. Owing to largest amplitudes and best thresholds, 500 Hz appears better stimuli for clinical recording of oVEMPs. This is true irrespective of the peak complex being assessed is n1p1 or p1n2.