Exteroceptive suppression of temporalis muscle activity: a blind study of tension-type headache, migraine, and cervicogenic headache.

Exteroceptive suppression of temporalis muscle activity (ES2 duration) has been reported to be reduced in chronic tension-type headache in previous open studies (with varying stimulus and analysis methods). We studied ES2 duration and latency in 11 patients with chronic tension-type headache, 10 patients with cervicogenic headache, 11 migraine patients, and 9 headache-free control subjects. The investigator was blinded as to the diagnostic category. Electrical stimuli of 0.5 ms duration and at least three times sensory threshold (median 9.6 mA) were used. ES2 was obtained in all but one (control) subject and the control ES2 duration mean was 33.5 (SD 8.5) ms (80% EMG amplitude reduction criterion). Mean ES2 duration differences were not found between the four groups. None of the headache patients had ES2 durations below the control group range. ES2 duration tended to decrease with increasing duration of headache history. Consistent asymmetries of ES2 latency and duration were not found among patients with (unilateral) cervicogenic headache. Thus, the role of ES2 in headache diagnosis still seems to be unsettled.