Vestibular Evoked Myogenic Potentials in Patients With Acoustic Neuromas

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Abstract
IT HAS been known that loud monaural clicks evoke myogenic potentials in the tonically contracting ipsilateral sternocleidomastoid muscle (SCM).1-3 Clinical studies have suggested that these potentials are of vestibular origin, especially of the inferior vestibular nerve region.1-6 Neurophysiological experiments using guinea pigs and cats have shown that primary vestibular afferents, especially saccular afferents, respond to relatively loud clicks.7-10 These myogenic potentials are called vestibular evoked myogenic potentials (VEMPs).6 Only a few reports exist concerning the clinical application of VEMPs. Murofushi et al6 reported that in a third of patients with vestibular neuritis, VEMPs are absent on the affected side and that absence of VEMPs might indicate involvement of the inferior vestibular nerve. Colebatch et al11,12 reported that patients with torticollis could show abnormal VEMPs and that VEMPs elicited in a patient with the Tullio phenomenon had an abnormally low threshold.