Speech-activated myoclonus: an uncommon form of action myoclonus.

We describe an unusual form of facial myoclonus activated by speech in 3 patients with different underlying neurological diseases and present the electrophysiological investigations and results of structural and functional imaging. In 1 of 2 patients in whom jerk-locked electroencephalogram (EEG) back-averaging was done, a cortical potential clearly preceded the facial jerks. In the second patient, a cortical potential preceding the jerk was not certain. In the third patient, the resting EEG contained outbursts of symmetric, slower frequencies of indeterminate significance. An epileptiform disorder was suspected in this patient.