The fibromyalgia and myofascial pain syndromes: a preliminary study of tender points and trigger points in persons with fibromyalgia, myofascial pain syndrome and no disease.

Four experts on myofascial pain syndrome (MFP) performed trigger point examinations and 4 experts on fibromyalgia performed tender point examinations on 3 groups of subjects (7 patients with fibromyalgia, 8 with MFP, and 8 healthy persons) while blinded as to diagnosis. Local tenderness was common in both disease groups (65-82%), but was elicited in a greater proportion of MFP experts' examinations (82%). Active trigger points were found in about 18% of examinations of patients with fibromyalgia and MFP, but latent trigger points were rare in all groups. A more liberal definition of trigger point, however, resulted in a 38 and 23% positive rate among patients with fibromyalgia and MFP, respectively. Taut muscle bands and muscle twitches were common (50 and 30%, respectively) and noted equally in all 3 diagnostic groups. Problems with reliability were identified for taut bands, muscle twitch, and active trigger points. Our data are exploratory and tentative, but suggest that attention to definition and reliability are required to advance our knowledge of these common syndromes.