Background & Aims

Temporomandibular joint disorder (TMD) is an orofacial pain disorder resulting from dysfunction in the temporomandibular joint (TMJ) and associated structures1,2,3. TMD pain can range from mild to debilitating and studies show that a significant portion of patients are unable to achieve adequate relief1. This may be due to the heterogenous nature of TMD pain. While TMD is typically considered a musculoskeletal disorder, it has been suggested to encompass non-nociceptive pain phenotypes as well4. It is unclear if other components of pain, such as neuropathic pain, may contribute to the severity of TMD in some cases. This study examines TMD profiles using validated pain scales, quantitative assessment of allodynia, hypoesthesia and pinprick thresholds and pain. We conducted an analysis of how clinical pain profiles differed among patients with chronic TMD. Our goal was to determine if neuropathic pain may be a be a component of TMD pain in some patients.

Methods

We recruited 327 patients with chronic TMD pain and examined neuropathic pain symptoms in the jaw and orofacial area via 2 validated questionnaires: the Douleur Neuropathique en 4 (DN4), the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS). We performed bedside testing to determine pinprick thresholds, the presence of dynamic and touch allodynia, and hypoesthesia in the orofacial area. A latent profile analysis was conducted to classify participants based on these neuropathic pain scale scores. We further measured pain severity via Graded Chronic Pain Scale (GCPS), and pain pattern across the whole body using the painDETECT questionnaire (PDQ). We also assessed the presence of Fibromyalgia via the Fibromyalgia Diagnostic Criteria as a potential covariable. We used linear regression, and analysis of variance statistical tests to determine group effects.

Results

We identified 2 subgroups of patients exhibiting TMD pain with a neuropathic pain-like symptom profile (TMD+NP, n = 53) and without (TMD-NP, n = 274) neuropathic pain-like symptoms. Results showed significant increase in the GCPS severity of pain for TMD+NP group (b = 2.1, p <0.001) and marginal differences in the duration of TMD pain (p = 0.06). There was no significant difference in widespread pain index (p = 0.11) or corresponding symptom severity (p =0.08). TMD+NP participants scored higher on the PDQ (b = 11.8, p< 0.001), reported significantly more pain sites (b = 5.6, p<0.001) than TMD-NP participants. They also reported greater touch allodynia (b = 2.1, p < 0.001), dynamic allodynia (b =0.3 p< 0.001), and pinprick threshold (b =1.5, p < 0.001). In addition, we found greater hypoesthesia to both touch (b = 0.25, p <0.001) and pin prick (b = 0.25, p < 0.001) in the TMD+NP group. However, there was no significant difference in PDQ pattern of pain across the whole body.

Conclusions

This study outlines the presence of a subgroup of patients showing probable neuropathic pain components to their TMD pain. This suggests a possible heterogeneity of pain phenotypes in a pain condition that has been primarily associated with nociceptive pain. Future sensory testing and analyses will be needed to investigate this potential heterogeneity and the impact on clinical, social and behavioral outcomes in TMD.

References

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Presenting Author

Titilola Akintola

Poster Authors

Titilola Akintola

PhD

University of Maryland

Lead Author

E-mail

Topics

  • Specific Pain Conditions/Pain in Specific Populations: Orofacial Pain