Effects of Chemoradiation on Hearing in Patients with Head and Neck Malignancies: Experience at a Tertiary Referral Care Hospital.

Hearing loss as a side effect in patients with head and neck malignancies with chemoradiation is frequently ignored. Its effects on auditory functions are less studied and there are studies done on animals which are less reliable. The present study was undertaken to identify the type of hearing loss and also to quantify the degree of hearing loss in these patients. A prospective, descriptive study was undertaken in histologically proven head and neck cancer patients treated with cobalt 60 teletherapy who received a dose of 60-66 Grays (Gy) over a period of 6-7 weeks with concurrent Cisplatin 30 mg/m2 once weekly for 6 weeks. The study included 40 patients (80 ears) undergoing chemoradiation. A baseline pure tone audiometry and impedance audiometry was performed in all the cases prior to the therapy and the same was repeated immediately after the completion of treatment, at 8 and 16 weeks. The changes in pure tone level thresholds and impedance from baseline were correlated with the dose of radiation and chemotherapy. Sensori neural hearing loss (SNHL) and conductive hearing loss was observed in 82.5 and 17.5 % respectively. At the end of 16 weeks, SNHL was found in 27.5, 72.5 and 82.5 % at 2, 4 and 8 kHz respectively. In addition, Eustachian tube dysfunction and Otitis media with effusion was observed in 10 and 7.5 % of patients respectively which lead to conductive hearing loss. Further, it was noted that SNHL in patients with high risk site malignancy (81.8 %) was alarmingly higher compared with low risk site malignancy (18.1 %). The hearing loss at 62, 64 and 66 Gy in comparison to 60 Gy was statistically significant. Hearing loss, specially SNHL was the predominant finding in our study with >80 % of patients showing the inner ear damage due to irradiation of head and neck malignancies. Although, all the frequencies like 2, 4 and 8 kHz were significantly affected, SNHL was more marked in the latter two frequencies. Nearly, 90 % of the patients who had SNHL belonged to high risk site category of head and neck malignancies. Increasing the radiation dosage was directly proportional to the degree of hearing loss with the dose more than 60 Gy causing significant injury to the middle and inner ear.