Unilateral hypoglossal nerve atrophy as a late complication of radiation therapy of head and neck carcinoma: A report of four cases and a review of the literature on peripheral and cranial nerve damages after radiation therapy

Abstract

The case histories of four patients who developed hemiatrophy of the tongue from 3 to 9 years after a course of curative radiation therapy for carcinomas of the head and neck are presented. These patients were subsequently followed for from 1½ to 6 years without local recurrence of the tumor, distant metastasis, or involvement of other cranial nerves, indicative of only a unilateral hypoglossal nerve atrophy. A review of the literature showed that peripheral and cranial nerve damages after radiation therapy have been reported for the optic nerve, hypoglossal nerve, oculomotor nerve, abducens nerve, recurrent laryngeal nerve, brachial plexus nerves, and peripheral nerves of the extremities. Review of clinical and experimental data indicated that in most cases, the damages were probably caused by extensive connective tissue fibrosis around and infiltrating the nerve trunks. Three possible types of peripheral and cranial nerve damages after radiation therapy are identified.