Temporomandibular disorders and chronic daily headaches in the community and in specialty care

Background Chronic daily headaches (CDHs) are often associated with temporomandibular disorders (TMDs). However, large studies assessing the relationship were conducted in general, and not clinical, populations. Thus, clinical exams were not completed. Clinic-based studies with expert diagnosis are, in turn, often small and may not be representative. Objective To contrast the demographic and clinical symptoms of CDH and TMD in participants within the general population relative to patients seen in a headache clinic. Methods All inhabitants 10 years and older of a small city in Brazil were interviewed. Those with more than 15 days of headache per month were examined by a team consisting of a neurologist, a dentist, and a physical therapist. Headaches were classified as per the Second Edition of the International Classification of Headache Disorders and TMD as per the Research Diagnostic Criteria. The procedure was repeated (by the same team) with CDH sufferers consecutively seen in a headache center. Results Of 1605 inhabitants interviewed, 57 (3.6%) had CDH, and 43 completed all physical assessments. For specialty care group, of 289 patients, 92 had CDH, and 85 completed all assessments. No significant differences were seen for gender and age, but education level was significantly higher among those recruited at specialty care. Muscular TMD happened in 30.2% of CDH patients from the community vs 55.3% in the headache center (difference of -25.1%, 95% confidence interval of difference = -40.8% to -9.4%). No TMD happened in 41.9% of those recruited from the population relative to 20% of those in the headache center (21.9%, 95% confidence interval = 6.7-37.1%). Conclusion Individuals with CDH recruited from the general population are significantly less likely to have CDH relative to those selected from the headache center. Issues of generalizability are of concern when conducting clinic-based studies on the topic.