Comorbid Painful TMD with Trigeminal Neuralgia and Atypical Facial Pain

Objectives: Trigeminal neuralgia (TN) and Atypical Facial Pain (AFP) are uncommon but extant neuropathic pain disorders seen in academic orofacial pain clinics. Painful TMD is known to be comorbid with a subset of AFP—patients with Atypical Odontalgia. However, TN-TMD comorbidity is unreported. This is clinically important because TN is classified into two categories: Type 1 and Type 2, and Type 2 pain is more constant, less intense, and has less favorable prognosis than Type 1. One possible explanation of Type 2 TN is the comorbid presentation of TMD with TN.
Methods: Retrospective review of electronic health records from the University of Minnesota was conducted among new patients seen within the TMD and Orofacial Pain Clinic between October 1, 2010 and October 1, 2019. Painful TMD was considered TMJ arthralgia, myalgia, or myofascial pain (masticatory/cervical muscles). Proportions of patients diagnosed with TN±TMD and AFP±TMD were calculated and differences between samples calculated using two-sample z-test (a=0.05).
Results: Over nine years, 7,855 new patients were evaluated. 136(1.7%) were diagnosed with TN, 315(4.0%) with AFP, and 16(0.2%) with both disorders. The proportion of patients with TN that also had painful TMD was 0.45(95%CI:0.37-0.53), while the proportion with AFP and painful TMD was 0.60(95%CI:0.54-0.65). The proportion of both pain disorders with painful TMD was 0.31(95%CI:0.14-0.56). The proportion of patients with comorbid TMD was statistically higher in patients with AFP compared to those with TN (p=0.0015).
Conclusions: The comorbid presentation of painful TMD with neuropathic orofacial pain disorders is common in orofacial pain practice. It is not known which pain disorder precedes the other, nor whether painful TMD comorbid with TN satisfies criteria for classification as Type 2 TN. Due to referral bias present in this clinic, prospective research investigating the relationship between TN and other neuropathic orofacial pain with painful TMD in other clinical settings is necessary.