The effect of electromyographic (EMG) biofeedback on frontalis and masseter muscle activity was compared with control conditions in two groups of patients with a diagnosis of myofascial pain dysfunction (MPD) syndrome. Patients were selected on the basis of clinical symptoms, radiographic evaluation, and a clinical examination. Depressed patients and patients with signs of a pathological condition in the temporomandibular joint were excluded. Both the experimental (EXP) and the control (CON) group went through two base-line screening sessions before treatment of the EXP group was started. Treatment consisted of eight biofeedback sessions, given twice a week for 4 weeks. Feedback was presented visually on a monitor. Treatment did not include any relaxation training. Control evaluations of both groups took place 1 week, 3 months, and 6 months after the end of treatment. The EXP group was able to reduce EMG levels in frontalis and masseter muscles significantly during training sessions. Follow-up data showed significantly reduced frontalis EMG levels in the EXP group after 3 and 6 months but not in the CON group. Both groups improved subjectively, as judged by reports on pain intensity and duration, but this improvement was significantly more pronounced in the EXP group. Objective clinical indices recorded throughout the study were uncorrelated with EMG changes or subjective reports. It is concluded that biofeedback training facilitated muscular relaxation and self-regulation in the EXP group and that visual EMG feedback, consisting of a patterning of frontalis and masseter muscle activity, can be recommended as an integrated part of MPD syndrome treatment.

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