Somatosensory profiles in subgroups of patients with myogenic temporomandibular disorders and Fibromyalgia Syndrome.

Some patients with myofascial pain from temporomandibular disorders (TMD) report pain in extra-trigeminal body regions. Our aim was to distinguish TMD as regional musculoskeletal pain syndrome (n=23) from a widespread pain syndrome (FMS; n=18) based on patients' tender point scores, pain drawings and quantitative sensory testing (QST) profiles. Referenced to 18 age- and gender-matched healthy subjects significant group differences for cold, pressure and pinprick pain thresholds, suprathreshold pinprick sensitivity and mechanical detection thresholds were found. Pain sensitivity in TMD patients ranged between those of FMS patients and healthy controls. The group of TMD patients was inhomogeneous with respect to their tender point count with an insensitive group (n=12) resembling healthy controls and a sensitive TMD group (n=9) resembling FMS patients. Nevertheless sensitive TMD patients did not fulfil diagnostic criteria for FMS in regard to widespread pain as shown by their pain drawings. TMD subgroups did not differ with respect to psychological parameters. The sensitive subgroup was more sensitive compared to healthy controls and to insensitive TMD patients in regard to their QST profile over all test areas as well as to their tenderness over orofacial muscles and trigeminal foramina. However, sensitive TMD patients had a short pain duration arguing against a transition from TMD to FMS over time. Data rather suggest an overlap in pathophysiology with FMS, e.g. a disturbance of central pain processing, in this subgroup of TMD patients. Those patients could be identified on the basis of their tender point count as an easy practicable screening tool.