The use of electromyography and muscle palpation in the diagnosis of tension-type headache with and without pericranial muscle involvement.

The Headache Classification Committee of the International Headache Society recently issued revised diagnostic criteria for headache disorders. According to these criteria, tension-type headache may be subclassified depending upon whether pericranial muscle disorder is found. The presence or absence of pericranial muscle disorder was to be determined by palpating the muscles for tenderness or by measuring electromyographic (EMG) activity. In this study, pericranial muscles were palpated, and EMG activity was measured in 27 episodic tension-type headache patients and 32 headache-free controls. All testing was done while the subjects were in a headache-free state. Muscle tenderness was positively associated with the diagnosis of tension-type headache. Headache subjects exhibited significantly higher levels of temporal EMG activity compared to controls, but EMG data were of little use in assigning individual subjects to diagnostic groups. Measures of muscle tenderness and hyperactivity were only weakly associated. Pericranial muscle tenderness and elevated EMG activity may index different aspects of abnormal muscle function.