Role of Cervical Vestibular Evoked Myogenic Potentials (cVEMP) as Outcome-Measure of Glycerol Test

Diagnosis of Meniere's disease is mainly clinical although many tests have been studied for efficacy in diagnosis of Meniere's disease. Glycerol test is a functional test to identify hydrops in Meniere's disease and can be done with PTA, Speech audiometry, otoacoustic emission, EcochG and cVEMP as its outcome measures. The study aimed to compare two outcome measures of glycerol test to identify Meniere's disease; to determine whether the stage of Meniere's disease affected glycerol outcomes; and to attempt to identify independent variables that could predict outcomes of glycerol test. 26 ears of 20 Meniere's disease participants were evaluated using PTA-based and cVEMP-based glycerol tests. Each test identified ten of 26 ears with Meniere's disease; and high agreement was noted in the two outcome measures. The stage of Meniere's disease based on four frequency hearing threshold average was not associated with outcome of glycerol test, but staging of Meniere's disease based on symptom duration was associated with glycerol test results. As the duration of symptoms increased there was lesser chance of positive outcomes on glycerol test; but intermediate stages of Meniere's disease showed positive outcomes. Variables such as age, gender, severity of hearing loss, duration of symptoms and pre-glycerol cVEMP measurements could not predict glycerol test outcomes. PTA-based and cVEMP- based glycerol tests hold promise in the test battery for identification of Meniere's disease. Positive findings on the test lead to confirmatory diagnosis but a negative glycerol test does not rule out Meniere's disease.