EMG levels in the occipitofrontalis muscles under an experimental stress condition.

In view of the importance attached to the frontalis muscles by researchers into the etiology of head pain and its treatment by biofeedback techniques, it is surprising that no data have yet been reported on the functioning of the occipitalis muscles, which have a close physiological relationship to the frontales. This study explores the response of the frontalis and occipitalis muscles under a condition of experimental stress. Migraine and tension-headache sufferers were separately compared with a headache-free control group under four conditions: baseline, while listening to instructions, while carrying out an auditory vigilance task, and for a further resting period equivalent to baseline. Results showed that tension levels in the frontalis muscles were not elevated at rest in any of the experimental groups, nor were they significantly responsive to the experimental task. The occipitales however proved to have significantly higher levels in both the tension-headache and migraine groups during the task and recovery periods. The results for the tension group reached significance because of a drop in control group values. These results may have significance in determining the best site for electrode placement in biofeedback.