Post Irradiation Hearing Loss In Head/Neck Patients In Lagos, Nigeria

A prospective study was conducted at Lagos University Teaching Hospital on patients with malignancies of the head and neck region treated with external beam irradiation type and severity of hearing loss. Each patient had a pre-irradiation and post irradiation pure tone audiogram at 3 weeks, 8 weeks and 6 months. Following completion of radiotherapy serial post irradiation audiogram threshold was compared with pre-treatment threshold. An increase of 10 dB HL (decibel hearing level) or greater was considered significant. Radiation dose ranged from 45-55Gy in twenty to twenty-five fractions per weeks over four to five weeks treatment. Patients that received chemotherapy as adjunctive to therapy during the period of the study were excluded. A total of 40 patients (80 ears) completed the audiological follow up out of ninety four patients seen during the study period .Age ranged between 4-79 years. The tumor site distribution showed 20% in the nasopharynx, 25% in the larynx, 15% in the nose and paranasal sinuses and 10% in the parotid. 7.5% in the oral cavity and mandible respectively and 5% in the ear. Majority 33 (82.5%) were sqaumous carcinoma, 10% were sarcoma and 5% were adenocarcinoma.Pre-radiation hearing assessment revealed 62 ears (77.5%) with normal hearing, 8ears (10%) with mild SNHL and 5 ears (6.25%) with mild and moderate CHL respectively. Final post radiation hearing assessment after 6 months revealed normal hearing in 64 ears (80%), 11 ears (13.8%) with mild SNHL and 2 ears (2.5%) with moderate SNHL. 1.25% with moderate conductive hearing loss and 2 ears (2.5%) with mixed loss. Negative effect of radiotherapy post radiation was seen in 5 ears (6.25%) mainly in mandibular, parotid and ear tumours. The study shows that hearing loss after external beam irradiation could be a significant side effect after radiotherapy in head and neck cancer patients, hence patients should be informed during the pre-treatment counseling period and audiological assessments should be an integral part of pre-therapy evaluation for medicolegal reasons.