Subjective, clinical and EMG effects of biofeedback and splint treatment.

Patients suffering from myofascial pain dysfunction (MPD) were trained to maintain constant levels of EMG masseter activity with the aid of biofeedback. Treatment effects were compared with the effects of a nightly full-coverage splint and with a no-treatment control group. The biofeedback group showed significantly more improvement in clinical dysfunction and subjective symptoms related to pain and mandibular movement than either the splint group or the control group. The results of the splint group were not substantially different from the control group. The EMG results indicate that during biofeedback the ratio between EMG activity of the trained and the non-trained masseter shifted towards a higher contribution of the trained muscle. This effect was significant at high task levels. During biofeedback EMG task performance improved but this effect did not generalize to non-feedback situations. It is suggested that the treatment effects of biofeedback depend upon the increase in perceived control reported by the biofeedback group.