Contralateral cervical vestibular evoked myogenic potential (cVEMP) response elicited by AC stimuli

BackgroundCervical VEMP elicited by air-conducted acoustic stimuli (AC cVEMP) is considered as a valuable test for assessment of saccular function. The dominant component of this response, which is composed of a biphasic positive-negative deflexion, can be recorded from the tensed ipsilateral sternocleidomastoid muscle. It is conveyed by inhibitory connections from the irregular saccular afferents. The contralateral response, which has opposite polarity, is in general not studied in clinical practice. It probably reflects excitatory influences conveyed from irregular afferents of the utricle.ObjectiveThe purpose of this study was to ascertain whether this contralateral response has any clinical value.MethodsAC cVEMPs of 117 control subjects and 353 patients with balance problems and/or BPPV were subjected to retrospective analysis. The contribution of the contralateral excitatory response to the whole response (i.e., amplitudes of the contralateral plus ipsilateral responses) was expressed in percentages calculated according to Jongkee's formula.ResultsThere was statistically significant increase in the contribution of the contralateral excitatory component to the whole response in patients.ConclusionsThis may imply somewhat lower vulnerability of the contralateral utricular response to various disease processes and/or aging.