A REVIEW OF ELECTROCOCHLEOGRAPHY - INSTRUMENTATION SETTINGS AND METAANALYSIS OF CRITERIA FOR DIAGNOSIS OF ENDOLYMPHATIC HYDROPS

This paper reviews the literature on instrumentation settings used for transtympanic (TT-ECOG) and extratympanic electrocochleography (ET-EC OG). There is wide variation with regard to the applied stimulus, the settings and interpretation of ECOG results. For most physicians, the presence of endolymphatic hydrops is indicated either by the summating /action potential (SP/AP) ratio for click stimuli or the SP amplitude after lone bursts. Different upper limits have been proposed to discri minate hydropic from non-hydropic ears. Based upon a meta-analysis and classification criteria obtained from multivariate statistics. the au thors propose that an SP/AP ratio with click stimulation >0.35 using T T-ECOG, or >0.42 using ET-ECOG, is indicative of hydrops. With tone bu rst stimulation set at a repetition rate of 30-40 stimuli per second, a SP of < -2 mu V using TT-ECOG for at least one frequency within the range 0.5-8.0 kHz is considered pathologic.