Objective: To assess the local and referred pain areas and pain characteristics evoked from temporalis muscle trigger points (TrPs) in chronic tension-type headache (CTTH).
Methods: Thirty CTTH patients and 30 age and sex-matched controls were studied. A headache diary was kept for 4 weeks to substantiate the diagnosis and record the pain history. Both temporalis muscles were examined for the presence of myofascial TrPs in a blinded fashion. The local and referred pain intensities, referred pain pattern, and pressure pain threshold were recorded.
Results: Referred pain was evoked in 87% and 54% on the dominant and nondominant sides in CTTH patients, which was significantly higher (P<0.001) than in controls (10% vs. 17%, respectively). Referred pain spread to the temple ipsilateral to the stimulated muscle in both patients and controls, with additional referral behind the eyes in most patients, but none in controls. CTTH patients reported a higher local [visual analog scale (VAS): 5.6+/-1.2 right side, 5.3+/-1.4 left side] and referred pain (VAS: 4.7+/-2 right side, 3.5+/-2.8 left side) intensity than healthy controls (VAS: 0.8+/-0.7 right side, 0.7+/-0.7 left side for local pain; and 0.3+/-0.2 right side, 0.4+/-0.3 left side for referred pain) in both temporalis muscles (both, P<0.001). The local and referred pain areas were larger in patients than in controls (P<0.001). Twenty-three out of 30 CTTH patients (77%) had active TrPs in the temporalis muscle leading to their usual headache (17 patients on the right side; 12 on the left side, whereas 6 with bilateral active TrPs). CTTH patients with active TrPs in either right or left temporalis muscle showed longer headache duration than those with latent TrPs (P=0.004). CTTH patients showed significantly (P<0.001) lower pressure pain threshold (1.1+/-0.2 right side, 1.2+/-0.3 left side) as compared with controls (2.5+/-0.5 right side, 2.6+/-0.4 left side).
Conclusions: In CTTH patients, the evoked local and referred pain from active TrPs in the temporalis muscle and its sensory characteristics shared similar patterns as their habitual headache pain. Local and referred pain from active TrPs in the temporalis muscles may constitute one of the sources contributing to the pain profile of CTTH.