Transtympanic Versus Tympanic Membrane Electrocochleography in Examining Cochleovestibular Disorders

The use of electrocochleography (EcoG) is considered to be of clinical value in otological diagnosis. Non-invasive ear canal (EC) and tympanic membrane (TM) EcoG recording techniques, and invasive transtympanic (TT) technique are the methods used for objective assessment of cochlear function. In this study, eight adults (16 ears) with suspected Meniere's disease were examined using a newly designed, disposable tympanic electrode and a traditional, thin transtympanic needle. The amplitudes of the TT electrode responses were 4-6-fold larger than those produced by the TM electrode. The morphology of the waveforms for the two recording techniques was nearly identical. The mean amplitudes of the action potential (AP) obtained with the TM electrode were 2.39-3.73 w V, and with the TT electrode 14.08-19.60 w V, depending on the stimulus intensity. For the summating potential (SP), the TM and TT electrodes had mean amplitudes of 0.82-1.60 w V and 3.53-5.81 w V, respectively. The SP/AP ratios were ...