Ocular neuromyotonia after radiotherapy for nasopharyngeal carcinoma: the first reported case in Hong Kong

Abstract

Double vision is a common symptom. Usually, the cause of diplopia is due to cranial nerve palsies, such as third, fourth, or sixth nerves palsies. Sometimes, the cause may be due to a rare neuromuscular disorder. This report is of a Chinese woman with a history of radiation therapy for nasopharyngeal carcinoma who subsequently developed double vision and was found to have intermittent left-sided lateral rectus muscle spasm. The patient underwent complete neuro-ophthalmic assessment, including investigation of the eyelid posi- tion, ocular motility, force duction test, alignment, appropriate blood tests, and imaging. Her condition was fi diagnosed as ocular neuromyotonia secondary to radiation therapy. To the authors’ knowledge, this is the first patient from Hong Kong to be reported.