The role of radiation in delayed hearing loss in nasopharyngeal carcinoma.

Although radiation damage to the inner ear can be induced experimentally in animals, its incidence in humans as a complication of therapy for nasopharyngeal carcinoma (NPC) remains a matter of conjecture due to inadequate histological validation. A case of advanced NPC with a mixed conductive and neurosensory hearing loss is presented that at necropsy showed tumour invasion of the VIIIth cranial nerve in the internal auditory meatus with associated infection. The architecture of the organ of Corti was well-preserved despite heavy doses of radiation but degeneration, the cause of which could not be substantiated, was present in the auditory nerve pathway. A diagnosis of radiation damage to the end-organ of hearing in the absence of supporting histological evidence should be made with caution.