EMG activity in pericranial muscles during postural variation and mental activity in healthy volunteers and patients with chronic tension type headache.

EMG activity was recorded over frontalis, temporalis and trapezius muscles in a supine position, a standing position and during a mental task in 32 female patients suffering from chronic tension-type headache and in 20 healthy volunteers. Measurements in patients were made before and after biofeedback therapy. All EMG levels were on average significantly higher in patients than in controls. 62.5% of patients had at least one abnormal EMG level, but only 34% were beyond the normal range, if 1 muscle and 1 recording condition was considered. EMG levels were not correlated with headache severity, anxiety or response to biofeedback treatment. It is therefore suggested that pericranial EMG activity is not pathogenetic in chronic tension type headache, but merely one of several pathophysiologic changes, that are produced by a central dysfunction.