Cervical and Ocular Vestibular Evoked Myogenic Potentials Are Sensitive to Stimulus Phase

Abstract

Sinusoidal forces with frequencies of 100 and 500 Hz and initial positive or negative polarities were delivered to the mastoids and Fz in normal subjects. We investigated whether the cVEMPs and oVEMPs evoked were sensitive to the polarity (phase) of vibration. With mastoid stimulation at 100 Hz, medial head acceleration produced cVEMPs with earlier latency (15.5 ms) than lateral acceleration (19.7 ms) and oVEMPs with later latency (13.8 ms) than lateral acceleration (10.6 ms). As the stimulus frequency increased, the difference in latency decreased, but was still present at 500 Hz. A similar pattern occurred following stimulation at Fz. Our results show that the initial direction of bone-conducted vibration affects both cVEMP and oVEMP properties even at relatively high frequencies.

Vestibular evoked myogenic potentials in practice: Methods, pitfalls and clinical applications

“…Responses can change polarity and/or latency with different sites of stimulation. The effects are much greater for taps and low frequency tone bursts, but are still present with 500 Hz stimuli (Cai et al, 2011). When delivered to the anterior forehead around the hairline, stimuli that begin with acceleration toward the skull (as with a standard tendon hammer tap) produce earlier responses than those that begin with acceleration away from the skull, but the effects for other midline sites differ (Govender and Colebatch, 2017, Govender and Colebatch, 2018).…”

Single motor unit responses underlying cervical vestibular evoked myogenic potentials produced by bone-conducted stimuli

“…All of these stimuli, except for the outward tap, have been shown to evoke cVEMPs with typical positive-negative (i.e. p13-n23) polarity (Cai et al, 2011;Colebatch et al, 1994;Rosengren et al, 2009), while the outward tap produces a cVEMP with the opposite polarity (negative-positive) (Rosengren et al, 2009). We predicted that the single motor unit responses would mirror the surface responses and change with changing stimulus type.…”

“…The most common types of stimulus delivered by these vibrators to evoke cVEMPs are: sine waves, often at 500 Hz and sometimes delivered to the forehead near Fz (e.g. Cai et al, 2011;Manzari et al, 2010Manzari et al, , 2012; square waves, either delivered to the forehead (e.g. Taylor et al, 2011Taylor et al, , 2012 or inion (e.g.…”

“…In contrast, when the stimulus has a lower dominant frequency, such as a tendon hammer tap, the skull acceleration is approximately equal on both sides but is oppositely-directed (e.g. both sides move away from the hammer, causing the ipsilateral ear to move medially and the contralateral ear to move laterally) and the cVEMPs have similar size but different polarity and/or peak latency in the ipsilateral and contralateral SCM muscles (Brantberg et al, 2002(Brantberg et al, , 2003(Brantberg et al, , 2008(Brantberg et al, , 2009Cai et al, 2011;Rosengren et al, 2009;Todd et al, 2008). Therefore different types of AC and BC stimulation probably activate distinct, although often overlapping, populations of vestibular otolith afferents.…”

Letter to the Editor

“…In contrast to previous reports, they found a broad tuning curve with no clear best frequency. They suggest that this differs from the tuning studies by Todd et al (2008Todd et al ( , 2009a, Cai et al (2011), andZhang et al (2012) and explains the differences in frequency tuning of the OVEMP found among the studies. Burgess et al (2013) have emphasized that their tuning study made use of the initial negativity, the "n10" wave.…”