Clinical application of non-invasive electrocochleography.
Non-invasive extratympanic electrocochleography (ECochG) was performed in normal-hearing subjects and patients with sensorineural deafness. Action potential (AP) threshold, N1 input-output function, waveform, summating potential (SP) are presented. AP thresholds were within 15 dB in normal-hearing ears and within 30 dB in hearing-impaired ears above subjective thresholds for the click. Correlational analysis showed that click-evoked AP thresholds are best correlated to pure tone thresholds at 2 to 4 kHz. Four types of N1 input-output functions were classified. Normal functions appeared in moderate high tone loss only at 8 kHz and low tone loss with almost normal threshold above at 4 kHz. Many ears with a flat loss had recruiting responses, while many ears with a high tone loss had either dissociated responses or responses with prolonged latency. Several types of waveforms were distinguished. Enhanced--SP was observed in Meniére's disease and late congenital syphilis to which endolymphatic hydrops is common. The clinical value of the non-invasive ECochG is discussed.
D000293:Adolescent; D000328:Adult; D000368:Aged; D001299:Audiometry; D001300:Audiometry, Evoked Response; D001309:Auditory Threshold; D002648:Child; D003051:Cochlea / Q000502:physiology / Q000503:physiopathology*; D003638:Deafness / Q000175:diagnosis*; D006801:Humans; D007759:Labyrinth Diseases / Q000175:diagnosis; D008575:Meniere Disease / Q000175:diagnosis; D008875:Middle Aged