Tension headache may actually be temporomandibular muscle and joint disorder

May 23 2006

People whose recurrent headaches have been diagnosed as tension-related actually may be suffering from temporomandibular muscle and joint disorder, or TMJD, a study headed by a researcher from the University at Buffalo's School of Dental Medicine has shown.

Results showed that examiners could replicate tension-headache symptoms in 82 percent of subjects by performing the clinical examination of the temporalis muscle, which is involved in TMJD.

Richard Ohrbach, D.D.S., Ph.D., UB associate professor in the Department of Oral Diagnostic Sciences, presented the study results at the American Association of Dental Research meeting held recently in Orlando, Fla.

The temporalis muscle is responsible for closing the jaw and is involved in chewing, but these core functions of that pair of muscles often are ignored when the presenting complaint is "headache," as opposed to jaw pain, Ohrbach said.

"Because headache is so incredibly common, it often is regarded as inevitable, and if sufferers label the pain as 'headache,' they may not seek help," he said. "Or if they do seek help, the label of 'headache' typically will propel the individual to a physician or neurologist for consultation.

"Knowledge about the intersection between jaw pain and headache is not well established, and consequently, jaw pain may be ignored in the differential diagnosis," Ohrbach added. "This can be most unfortunate for the individual, because TMJD can be very treatable, but if a jaw disorder is ignored, then treatment for the headache may not address all of the factors contributing to the headache."

The current study is part of an $8 million project to establish valid and reliable TMJD diagnostic criteria. Results will advance the field of TMJD research and aid clinicians in their practices.

Researchers at the University of Minnesota and the University of Washington, in addition to UB, are involved in the project.

An estimated 5-10 percent of the U.S. population suffer from TMJD severe enough to warrant treatment. These patients experience debilitating pain that can destroy quality of life. Diagnosing the disorder is problematic, however, due to overlap with other conditions, Ohrbach said.

TMJD usually involves more than a single symptom, rarely has a single cause and frequently involves multiple factors, including behavioral and emotional responses. Lacking a firm set of diagnostic tools, physicians and dentists often depend on their individual judgment to decide if a patient does or does not have the disorder, he noted.

The diagnostic criteria for TMJD being tested in this project are part of the established Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Headache diagnosis is based on the International Headache Society (IHS) guidelines. All examiners were been trained to use the "gold-standard" criteria for tension-type headache established by the IHS.

The study compared the diagnostic procedures for pain and the reproduction of "pain" vs. "headache" during the clinical examination. Procedures included a range of functional and orthopedic tests and standard pain sensitivity to pressure applied to the muscles associated with headache. The types of headaches considered included sub-clinical headaches, tension-type headaches and headaches exhibiting more symptoms than are accepted for tension-type headaches, such as the "mixed headache," migraine or "migraine-type" headaches

The study involved 583 participants -- 82.3 percent female and 17.7 percent male -- who were recruited as cases from the community based on the presence of symptoms clearly associated with TMJD. Based on IHS criteria, 31.5 percent, or 152 participants, were diagnosed with tension-type headache by the examiners.

Additional researchers on the study were Yoly Gondalez, D.D.S., from UB; John O. Look, D.D.S., Ph.D., Eric L. Schiffman, D.D.S., and Wei Pan, Ph.D., from the University of Minnesota, and Edmond L. Truelove, D.D.S., from the University of Washington.