Teaching Video NeuroImages: tongue myokymia following head and neck radiotherapy for nasopharyngeal carcinoma.

Richard A. Rison, MD, FAANEM Said R. Beydoun, MD, FAAN, FAANEM A 39-year-old woman with nasopharyngeal carcinoma underwent partial resection along with head and neck radiation therapy. Approximately 10 months later she developed progressive difficulty swallowing and facial spasms. Neurologic examination was significant for dysarthric speech and prominent rippling and wavelike movements of the tongue (see video on the Neurology Web site at www.neurology.org). Needle electromyography revealed myokymic discharges of the tongue in addition to the right-sided facial muscles. Radiation therapy may damage the hypoglossal nerve with subsequent hyperexcitability of the axon membrane and cause myokymia of the tongue, similar to myokymic discharges associated with brachial plexopathies after radiation therapy.1,2