TYMPANIC ELECTROCOCHLEOGRAPHY FOR DIAGNOSIS OF MENIERES-DISEASE

Objective: Tympanic electrocochleography (ECOG) is a noninvasive techn ique for recording cochlear potentials with an electrode placed on the tympanic membrane. Electrocochleography is used clinically in the eva luation of patients for endolymphatic hydrops. This study was undertak en to obtain normative data for ECOG responses to clicks and tone burs ts and to determine clinical indicators that result in high test speci ficities. Design: Three cochlear potentials were measured; the eighth nerve compound action potential, the cochlear microphonic, and the sum mating potential. The subjects were 53 normal hearing adults with nega tive histories for symptoms of Meniere's disease. The ECOG responses w ere measured with a silver wire-rayon wick electrode that was placed o n the tympanic membrane under direct microscopic visualization. Stimul i were condensation, rarefaction, and alternating polarity clicks and 1- and 2-kHz tone bursts. Results: Measures that appear to be useful i n the evaluation of endolymphatic hydrops include the summating potent ial to action potential ratio, action potential latency difference to condensation and rarefaction clicks, and the tone-burst-evoked summati ng potential. Relationships among these measures were investigated, an d abnormal criteria were determined that result in test specificities of 95%. Conclusions: Meniere's disease is viewed as a progressive dise ase in which ECOG characteristics vary with the disease state. Cases a re presented to illustrate ECOG responses in various stages of the dis ease. The normative data presented in this article are useful for the detection of Meniere's disease in its early stages.