Abstract
Background The cervical vestibular evoked myogenic potential (cVEMP) is a vestibular response
that is produced by the saccule in response to intense, often low-frequency, short-duration
auditory stimuli, and is typically recorded from a contracted sternocleidomastoid
(SCM) muscle. Previous research has shown that the amplitude of the cVEMP is related
to the amount of SCM electromyographic (EMG) activity.
Purpose The aim of this study was to determine the influence of various remote motoric maneuvers
on the amplitude of the cVEMP, as well as whether they influence the level of SCM
EMG activity.
Research Design The cVEMP was recorded from the left SCM muscle to left ear stimulation, in response
to the SCM condition, as well as three different motoric maneuvers (jaw clench, eye
closure, and the Jendrassik maneuver). EMG activity was also varied between 50, 75,
and 100% of maximal EMG activity.
Study Sample Data from 14 healthy subjects, with a mean age of 25.57 years (standard deviation = 5.93
years), was included in the present study.
Data Collection and Analysis Mean latency and amplitude of the cVEMP were compared across the four conditions
and varying magnitudes of EMG contraction. SPSS 26 was used to statistically analyze
the results.
Results cVEMP latency did not vary across condition. cVEMP amplitude decreased with decreasing
EMG magnitude. SCM contraction with jaw clench produced the largest increase in cVEMP
amplitude; however, this condition was not significantly different from the SCM condition
alone. SCM contraction with the Jendrassik maneuver produced a cVEMP amplitude that
was similar and not statistically different from SCM contraction alone, and the addition
of the eye closure maneuver to SCM contraction resulted in the lowest cVEMP amplitude,
which was found to be statistically different from the standard SCM condition at 100
and 75% EMG activity. The amplitude relationship across the conditions was not found
to vary with changes in EMG activity; however, a significant increase in EMG amplitude
was found during the 50% muscle contraction condition when subjects performed the
Jendrassik maneuver in addition to the standard SCM contraction.
Conclusions The addition of the eye closure maneuver to SCM contraction resulted in a significant
decrease in cVEMP amplitude, while the addition of the Jendrassik maneuver resulted
in a significant increase in EMG activity at the lowest level of SCM activation (i.e.,
50%). Additional research is necessary to determine how motoric maneuvers influence
the cVEMP amplitude, and whether the results are also dependent on how SCM contraction
is being produced (e.g., while supine vs. sitting).
Keywords
saccule - vestibular System - vestibular Function Test - electromyography - sternocleidomastoid
Muscle - cervical vestibular evoked myogenic potential (cVEMP)
