CENTRAL AND PERIPHERAL MECHANISMS IN CHRONIC TENSION-TYPE HEADACHE

The second exteroceptive suppression of masseter muscle activity (ES2) and tenderness in pericranial muscles were evaluated in 112 young adu lts who met IHS criteria in the following diagnostic classifications: 31 chronic tension headache, 31 episodic tension headache, 33 migraine without aura and 17 migraine with aura, An additional 31 subjects ser ved as controls. Pericranial muscle tenderness better distinguished di agnostic subgroups and better distinguished recurrent headache suffere rs from controls than did masseter ES2, Chronic tension headache suffe rers exhibited the highest pericranial muscle tenderness, and controls exhibited the lowest tenderness (P < 0.01). All chronic tension heada che sufferers exhibited muscle tenderness in at least one of the peric ranial muscles evaluated, while tenderness was exhibited by 52% of con trols. The association between pericranial muscle tenderness and chron ic tension headache was independent of the intensity, frequency, or ch ronicity of headaches. Our findings raise the possibility that pericra nial muscle tenderness is present early in the development of tension headache, while ES2 suppression only emerges later in the evolution of the disorder.