Palatal myoclonus. Reflex activation of contractions.

We report two unusual features of a 37-year-old man with palatal myoclonus. Although the rhythmic palatal contractions of this disorder are usually incessant, he was able to voluntarily suppress them for minutes. During periods of suppression, specific voluntary actions using the left side of his body, but not the right, reliably elicited single contractions. Various stimuli to the left side of his body, but not the right, also produced single contractions. Stimulation of trigeminal nerve branches evoked palatal electromyographic discharge after 55 ms. Microsurgical vascular decompression of posterior fossa neural structures led to improvement of several of the patient's symptoms and signs.