Oscillatory activity in different motor subsystems in palatal myoclonus. A case report.

In a patient with palatal myoclonus the mutual interaction between voluntary movements and the myoclonic activity was analysed. Amplitude and frequency of myoclonic activity in hand muscles were modulated by flexions and extensions. A 1:1 relationship was found between EMG-bursts in hand muscles and palatal movements. A 1:2 relationship was found between eye and finger movements. Resetting of myoclonus in the abductor digiti minimi muscle occurred after cutaneous ulnar nerve stimulation. It is suggested that feedback plays an important role in the generation of the oscillatory activity in PM in addition to pacemaker activity in brainstem neurons.