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.