Ocular neuromyotonia--an unusual ocular motility complication after radiation therapy for nasopharyngeal carcinoma.

The incidence of nasopharyngeal carcinoma is high amongst the Chinese population in Singapore. Abnormal ocular motility, like abducens nerve palsy, is often a presenting feature. Ocular motility problems can also arise as a complication from the treatment or tumour recurrence. This is a case report of a patient who had been treated for nasopharyngeal carcinoma with radiotherapy 13 years ago. She presented with paroxysmal diplopia and the clinical findings were consistent with ocular neuromyotonia. She responded favourably to oral carbamazepine. Ocular neuromyotonia is uncommon and it has never been reported in the local literature. Recognition of the condition is of both diagnostic and therapeutic significance.