Our aim was to describe the referred pain patterns and size of areas of trigger points (TrPs) in the masticatory and neck-shoulder muscles of women with myofascial temporomandibular disorders (TMD). Twenty-five women with myofascial TMD and 25 healthy matched women participated. Bilateral temporalis, deep masseter, superficial masseter, sternocleidomastoid, upper trapezius and suboccipital muscles were examined for TrPs by an assessor blinded to the subjects' condition. TrPs were identified with manual palpation and categorized into active and latent according to proposed criteria. The referred pain areas were drawn on anatomical maps, digitalized, and measured. The occurrence of active (P < .001) and latent TrPs (P = .04) were different between groups. In all muscles, there were significantly more active and latent TrP in patients than controls (P < .001). Significant differences in referred pain areas between groups (P < .001) and muscles (P < .001) were found: the referred pain areas were larger in patients (P < .001), and the referred pain area elicited by suboccipital TrPs was greater than the referred pain from other TrPs (P < .001). Referred pain areas from neck TrPs were greater than the pain areas from masticatory muscle TrPs (P < .01). Referred pain areas of masticatory TrPs were not different (P > .703). The local and referred pain elicited from active TrPs in the masticatory and neck-shoulder muscles shared similar pain pattern as spontaneous TMD, which supports the concept of peripheral and central sensitization mechanisms in myofascial TMD.
Perspective: The current study showed the existence of multiple active muscle TrPs in the masticatory and neck-shoulder muscles in women with myofascial TMD pain. The local and referred pain elicited from active TrPs reproduced pain complaints in these patients. Further, referred pain areas were larger in TMD pain patients than in healthy controls. The results are also in accordance with the notion of peripheral and central sensitization mechanisms in patients with myofascial TMD.
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