Electromyographic investigations in torticollis.

In 13 patients with torticollis, the electromyographic (EMG) activity in the neck muscles at rest was investigated before, during and after stimulation of the H1 bundle (in horizontal torticollis) and inner part of oral ventral nucleus (in the rotatory form), as well as after coagulation. Three EMG types of torticollis-spasmodic, myoclonic and mixed - could be differentiated. During the 8-, 25- and 50-Hz stimulations, a diminution in the amplitude and frequency of muscle potentials, followed by electric silence, was most often obtained; in general, the electric silence was preceded by a rhythmic activity of grouped potentials. Following coagulation, no spontaneous EMG activity was any longer recorded in the neck muscles, in the majority of the cases.