Background: The objective was to compare and correlate disability, pain intensity, the impact of headache on daily life and the fear of movement between subgroups of patients with chronic temporomandibular disorder (TMD).
Methods: A cross-sectional study was conducted in patients diagnosed with chronic painful TMD. Patients were divided into: 1) joint pain (JP); 2) muscle pain (MP); and 3) mixed pain. The following measures were included: Craniomandibular pain and disability (Craniofacial pain and disability inventory), neck disability (Neck Dsiability Index), pain intensity (Visual Analogue Scale), impact of headache (Headache Impact Test 6) and kinesiophobia (Tampa Scale of Kinesiophobia-11).
Results: A total of 154 patients were recruited. The mixed pain group showed significant differences compared with the JP group or MP group in neck disability (p < 0.001, d = 1.99; and p < 0.001, d = 1.17), craniomandibular pain and disability (p < 0.001, d = 1.34; and p < 0.001, d = 0.9, respectively), and impact of headache (p < 0.001, d = 1.91; and p < 0.001, d = 0.91, respectively). In addition, significant differences were observed between JP group and MP group for impact of headache (p < 0.001, d = 1.08). Neck disability was a significant covariate (37 % of variance) of craniomandibular pain and disability for the MP group (β = 0.62; p < 0.001). In the mixed chronic pain group, neck disability (β = 0.40; p < 0.001) and kinesiophobia (β = 0.30; p = 0.03) were significant covariate (33 % of variance) of craniomandibular pain and disability.
Conclusion: Mixed chronic pain patients show greater craniomandibular and neck disability than patients diagnosed with chronic JP or MP. Neck disability predicted the variance of craniofacial pain and disability for patients with MP. Neck disability and kinesiophobia predicted the variance of craniofacial pain and disability for those with chronic mixed pain.
Keywords: Chronic pain; Craniofacial disability; Headache; Neck disability; Temporomandibular disorders.