title: Tension headache patients: a comparison of a recruited subject sample and a clinic-based subject sample.
mesh_terms: D000328:Adult; D005152:Facial Muscles / Q000503:physiopathology; D005260:Female; D006261:Headache / Q000503:physiopathology / Q000523:psychology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction