Optimum Response Filter Setting for Air Conduction-Induced Ocular Vestibular Evoked Myogenic Potential.

BACKGROUND: A wide range of normative values of amplitude and latencies can be noticed in the publications on ocular vestibular evoked myogenic potential (oVEMP), possibly because of the inconsistent use of various stimulus and acquisition-related parameters such as response filter, gaze angle, onset polarity of stimulus, etc. One major nonuniform parameter across studies is the response filter. Several band-pass response filters such as 0.5-500, 1-1000, 5-500, 5-800, 10-750, 20-2000, 100-3000, and 200-1000 Hz have been used across published studies, and a wide range of normative values can be noticed. However, there is paucity of literature evidence to show that variations in response filters could cause alterations in oVEMP response.

PURPOSE: This study aimed to investigate the effects of changes in response filter setting on oVEMP.

RESEARCH DESIGN: Normative study using repeated measures research design.

STUDY SAMPLE: Young adults in the age range of 18-35 years (N = 150) and older adults in the age range of 60-70 years (N = 10).

INTERVENTION: Contralateral air conduction oVEMP.

DATA COLLECTION AND ANALYSIS: Contralateral air conduction oVEMP was obtained from only one ear of all participants. Low-pass filters (LPFs) of 500, 700, 1000, 1500, 2000, and 3000 Hz and high-pass filters (HPFs) of 0.1, 1, 10, and 30 Hz were used in all possible combinations of one LPF and one HPF to create band-pass filters. Latencies, peak-to-peak amplitude, and signal-to-noise ratio (SNR) were obtained for each response and comparison was made between various band-pass filters.

RESULTS: In young adults, there was a significant reduction in n1 and p1 latencies with increasing HPF and LPF (p < 0.01) and a significant reduction in peak-to-peak amplitude with increasing HPF (p < 0.008). The peak-to-peak amplitude was significantly not affected by changes in LPF (p > 0.05). In older adults, the response rate was better for 0.1- to 1000-Hz than 1- to 1000-Hz band-pass filters.

CONCLUSIONS: The optimum band-pass filter is 0.1-1000 Hz for recording oVEMP as it produces the largest amplitude oVEMP without compromising on SNR and causes improved response rate in older adults compared with 1- to 1000-Hz filters. Therefore, clinical recording of oVEMP should use 0.1-1000 Hz for obtaining large amplitude potentials and improving the chances of response detection in clinical population.