직업성 소음과 노화에 의한 와우 연접병증 1례

A Case of Occupational Noise-induced/Age-related Cochlear Synaptopathy

Objective: The purpose of this study was to analyze the audiological evaluation of older adults with a history of compressor noise exposure for the differentiation of cochlear synaptopathy. Method: The subject is a 74-year-old man who has been working intermittently in an air compressor noise environment for over 40 years. He is aware of tinnitus and hearing loss, but his main complaint is difficulty understanding speech in public. He reported not feeling bothered by loud noises. His audiologic evaluation included: Immittance audiometry (IA), pure tone audiometry (PTA), extended high frequency PTA (EHF-PTA), speech recognition score (SRS), transient evoked otoacoustic emission (TEOAE), distortion product otoacoustic emission (DPOAE), electrocochlear graphy (ECoG), and auditory brainstem response (ABR). Results: Middle ear pathology was excluded as IA, and EHF confirmed more than moderatly severe and severe hearing loss. The type of hearing loss was cochlear lesion by PTA, dynamic range, SRS in most and uncomfortable loudness level, occurrence of TEOAE, and i/o function of Ⅴ wave in ABR. The survival status of the inner hair cells was determined by TEOAE and DPOAE, and the abnormalities of the inner hair cell-spiral ganglion synapse were determined by SRS in noise, -SP/AP ratio of the ECoG, and Ⅰ/Ⅴ ratio of the ABR. Conclusion: If you have difficulty recognizing speech in noise due to noise exposure and aging process, you may have cochlear synaptopathy. Cochlear synaptopathy can be differentiated by the application and cross-validating number of audiological evaluations.