Electromyographic activity of neck muscles in patients affected by retrocollis under the influence of stimulation and coagulation of the prestitial nucleus of the midbrain.

In 2 patients with retrocollis, the positive effects obtained by stereotactic high frequency coagulation of the prestitial nucleus on the tonic activity of the neck muscle were studied electromyographically and clinically. Before the stereotactic therapy, electromyographic recordings at rest were recorded from the musculi splenii. During stimulation of the prestitial nucleus at frequencies of 8, 25 and 50 Hz, the EMG activity at rest diminished in frequency and amplitude and ultimately disappeared. Passage from the EMG recordings at rest to electrical silence took place, in one case, though a rhythmic activity of potentials grouped at 11/s. After coagulation of the prestitial nucleus, the involuntary contractions of neck muscles disappeared and electrical silence occurred. On reexamination 1 month later, the positive results were still present.