Electromyographic studies of congenital mirror movements.

We studied two patients with congenital mirror movements. In one, the movements were associated with impaired sensation and a cervicodorsal meningocele. In the other, no abnormality of the nervous system was found. In an EMG study, the normal temporal characteristics, response latency, duration, and amount of EMG on the normal and mirror sides suggest that similar motor commands are responsible for both voluntary and mirror movements.