Effects of radiotherapy for tumors of the larynx and hypopharynx in hearing levels

Abstract

The head and neck oncological patients are susceptible, either because of tumor location or the treatments performed, to changes of their ear structures. Due to close proximity of radiation field to the ear, radiotherapy induces short and long-term toxicities to the external, middle and internal ear. The aim of this study was to evaluate the impact of radiotherapy on the inner ear. We conducted a cross-sectional retrospective study of patients with cancer of the larynx and hypopharynx undergoing radiotherapy alone or adjuvant to surgery. The follow-up period was 1 year. Relevant clinical and audiological variables were analyzed. We included 15 patients, mostly males, with a median age of 66 years. Average hearing threshold (AHT) deterioration was found in 13 ears, with a median of 8.1dB. Mean bone conduction threshold at 4000 Hz, air conduction threshold at 8000 Hz at 12 months and the median of the final air conduction threshold at 10,000 Hz was significantly higher than the pre-treatment. A correlation was observed between final AHT and dosage of radiation per fraction. Thus, for each increase of 1 Gy per fraction there was an increase of 22.13 dB in the final AHT. About half of the patients had deterioration of the final AHT, proving, on the one hand, the sensorineural hearing loss associated with radiotherapy, while emphasizing the need to perform long-term follow-up protocols for early auditory rehabilitation of these patients.