일시적 청력역치상승 탐지에 대한 변조이음향방사와 전기와우도 검사의 유용성 비교 연구
- 원문 URL
Objectives: Early detection and monitoring are the most important measures in the prevention and treatment of noise-induced hearing loss. The distortion-product otoacoustic emission (DPOAE) test is known as the most sensitive test for early detection of noise-induced injury of cochlear hair cells. Recently, however, electrocochleography (ECoG) has also been reported to be a sensitive evoked-response test for detecting small, early, noise-induced changes in cochlear function. The purpose of this study was to investigate and compare the usefulness of the DPOAE test and ECoG for detecting the earliest noise-induced damage by analyzing the sensitivity and specificity of the two tests. Materials and Methods: After listening to music at 95.2 dBA SPL through a headphone for 2 h continuously, 23 healthy normal ears showed a temporary threshold shift (TTS) by more than 5 dB. Pure-tone audiometry, the DPOAE test, and ECoG were performed before, immediately after, and 24 h after the exposure in turn. Results: Before exposure, the average mean hearing threshold was 2.4?3.3 dB; this increased significantly to 9.9?3.2 dB immediately after exposure, and the largest shift was 13?6.5 dB at 4 kHz. It recovered to 2.8?3.6 dB by 24 h after the exposure. Before exposure, the DP/NF (amplitude above noise floor) was measured as 9.8?10.4, 23.5?6.4, 18.7?6.4, and 19.1?5.6 dB SPL at frequencies of 1, 2, 3, and 4kHz, respectively. Immediately after exposure, it decreased significantly at 2, 3, and 4 kHz to 16.6?7.6, 12.5?6.8, and 14.8?7.7 dB SPL, respectively. And it recovered to 12.9?6.4, 21.3?6.3, 19.0?5.8 and 18.3?5.7 at frequencies of 1, 2, 3 and 4 kHz by 24 h after the exposure. Marked increases in the SP and SP/AP ratio were recorded from 0.15?0.06 to 0.32?0.11 and 0.23?0.06 to 0.44?0.08 before and after the exposure, respectively. Significant widening of the AP wave was also observed on TTS phase. There were correlations between the hearing threshold and the absolute amplitude of DP and the DP/NF. We also observed a significant relationship between the hearing level and ECoG variables, such as the amplitude of SP, SP/AP ratio, and AP duration. The respective sensitivity of ECoG were 95.7% and 69.6% for the SP/AP ratio using 0.3 and 0.4 as the criterion. The respective sensitivity of the DPOAE test were 17.4%, 30.4%, 39.1% depending on DP/NF signal-to-noise(SNR) 3, 6, 9 dB. The respective specificity and FP of ECoG were 47.1%, 53.9% with 0.3 SP/AP ratio for the criterion, and 70.6%, 29.4% with 0.4. The respective specificity and FP of the DPOAE test were 100%, 0% with 3 dB DP/NF for the criterion, 100%, 0% with 6 dB as the criterion, and 88.2%, 12.8% with a 9 dB. Conclusion: Electrocochleography appears to provide more sensitive information than the DPOAE test for detecting a noise-induced temporary threshold shift. Further more data should be added with other instruments.