Clinical usefulness of glycerol vestibular-evoked myogenic potentials: preliminary report

The detection of intense sound-induced vestibular-evoked myogenic potentials (VEMPs) on the sternocleidomastoid muscle comprises the basis of the saccular function test. In order to evaluate the endolymphatic hydrops (EH) of the saccule of the inner ear, a glycerol VEMP (GVEMP) test was performed in 15 patients with unilateral typical Ménière's disease (UMD) and 7 with delayed endolymphatic hydrops (DEH). Using the GVEMP test, 8 of the 15 patients (53%) with UMD were evaluated as being abnormal. In addition, a greater number of patients (67%) were judged to be abnormal when the results of the GVEMP test were combined with those from a glycerol dehydration test, trans-tympanic electrocochleography (ECochG) or furosemide vestibulo-ocular reflex test (FVOR). Four of the 7 patients with DEH (57%) showed abnormal results in the GVEMP test. In particular, in patients with the ipsilateral type of DEH, only the GVEMP test was able to detect the affected side. These findings suggest that the GVEMP test is a new and useful test for EH, and that a test battery comprising the GVEMP test together with one of the other three tests is useful for diagnosing EH of the inner ear.