Myokymia and neuromyotonia of the tongue: a case report of complication of irradiation.

A 51-year-old man has suffered from progressive dysarthria since 1989. He himself noted slight weakness and tightness of the tongue, so that he was unable to perform motor tasks in a normal fashion. He was diagnosed as having nasopharyngeal carcinoma and had irradiation 70 Gy in 32 divided doses in 1979. Neurological examination revealed left-sided tongue atrophy and myokymia sparing of facial muscles involvement. Electrical discharges of myokymia and neuromyotonia were observed in the tongue muscles, suggesting hypoglossal nerve lesion with hyperexcitability of the axon membrance. Computed tomogram of brain did not show any evidence of recurrence of tumor; indicating that irradiation was the pathologic basis. Our report revealed that myokymia and neuromyotonia of the tongue was an unusual complication of irradiation.