Delayed radiation-induced bulbar palsy mimicking ALS.

We describe a patient presenting with progressive bulbar dysfunction and spasticity that clinically mimicked amyotrophic lateral sclerosis (ALS). Electromyography, however, showed no evidence of denervation and revealed a rare combination of peripheral and central myokymia. We feel that this pattern of myokymia represented a marker of neural injury from remote radiation therapy. Nervous system disorders resulting from therapeutic radiation are described, and potential pathophysiologic mechanisms underlying myokymia are discussed.