Factors Affecting Permanent Sensorineural Hearing Loss and Bone Conduction in Patients After Receiving Radiotherapy to the Head and Neck Region

OBJECTIVE: This study aimed to investigate the factors affecting permanent sensorineural hearing loss (SNHL) and causing changes in bone conduction (BC) thresholds over time in patients after receiving radiotherapy (RT) or chemoradiotherapy (CRT) to the head and neck region. METHODS: A total of 63 patients with irradiated HNC that were admitted to the Radiation Oncology Department between 2011 and 2018 were included in the study. All patients were assessed with pure tone audiometry at eight different time points (first before RT and last five years after completion of RT). A chi-square test was used to analyze the variables that affected permanent SNHL occurrence. Repeated measure analysis of variance was conducted to investigate the factors affecting change in the BC threshold at pure-tone average (0.5–2 kHz) and the air conduction (AC) threshold at 4 and 6 kHz frequencies over time. RESULTS: Median follow-up was 52 months (range, 12–110 months). SNHL was found in 18 (14%) of the 126 ears. According to the receiver operating characteristic analysis, the cut-off values of cochlear D(mean) and D(max) radiation doses were 40 Gy [p=0.017, area under the curve (AUC): 0.676] and 45 Gy (p=0.008, AUC: 0.695). D(mean) (≤40 Gy vs. >40 Gy) and D(max) (≤45 Gy vs. >45 Gy) cochlear doses and age (≤40 vs. >40 years) were determined as factors affecting SNHL in the chi-square test. Repeated measures showed that BC thresholds between 0.5–2 kHz and AC thresholds at 4 and 6 kHz increased over time. Age (≤40 vs. >40 years), treatment of head and neck cancer (RT vs. CRT), cisplatin use, and D(mean) (≤40 Gy vs. >40 Gy) and D(max) cochlear dose (≤45 Gy vs. >45 Gy) were important factors affecting the course of BC threshold over time. CONCLUSION: D(mean) and D(max) cochlear doses and age were found to be associated with permanent SNHL. Conduction thresholds worsened over time at all frequencies, and this trend was affected by cochlear doses, age, CRT, and cisplatin use.