The significance of otoacoustic emissions of cochlear injury in the radiotherapy

Objective To study the early diagnosis of Distortion Product Otoacoustic Emissions(DPOAE)of cochlear injury after radiotherapy(RT).Methods 32 ears in patients with Nasopharyngeal Carcinoma(NPC)or maxillary sinus carcinoma were included in the study.The pure tone audiometry,acoustic impedance and DPOAE were performed before RT,in the RT,after RT and 3 months after RT.The changes of each frequency were compared in the pure tone audiometric and DPOAE.Results DPOAE in the radiotherapy was changed after RT in the ears with good middle ear and cochlear functions.There were no statistically significant than those before RT at 1kHz〔(10±3.2〕dB]and 2kHz〔(12±5.9)dB〕(P﹥0.05),but there were statistically significant in those frequencies at 4kHz〔(11±1.8)dB〕,6kHz〔(15±6.6)dB〕and 8Hz〔(18±5.3)dB〕(P﹤0.05).And the changes of DPOAE were earlier than that of pure tone audiometric.Conclusion DPOAE can be used in early diagnosis of cochlear injury after radiotherapy.