The relationship between temporomandibular joint dysfunction (TMD) and whiplash is an area of strong debate in medical and engineering circles. Clinically, a great number of patients suffering from whiplash injuries report TMD problems; biomechanically, engineers have been unable to show what happens during a rear end collision that causes injury to the temporomandibular joint.
Part of the problem may very well be that TMD pain may simply be an integral part of neck pain, rather than a separate, unrelated lesion caused by the collision itself. This theory is given credence by a new study that looked specifically at the interrelationship between neck pain and TMD symptoms in the general population.
The goal of this study was to find associations between TMD and neck pain. The researchers used a standard questionnaire that focused on symptomatology of both neck pain and TMD. The authors evaluated TMD by the patient's experience of any joint sounds (such as clicking), stiffness or fatigue in jaws, difficulty with opening mouth wide or it locking in, and any facial or jaw pain. Neck pain was defined as, "a troublesome pain experienced within the last year in the neck area between the occipital bone and the spinous process of the seventh cervical vertebra." 438 subjects completed the questionnaire.
188 patients (38.9%) had "troublesome" neck pain. The authors noted that this rate increased with age, and affected females more than males. A history of trauma did not correlate to troublesome neck pain. 266 subjects (55.1%) were identified with TMD pain.
When the results of the study were analyzed statistically, the authors found that there is indeed a significant association between neck pain and TMD pain. In particular, the strongest relationship exists between neck pain and facial and jaw pain.
The authors also suggest some anatomical reasons why the two conditions are so closely linked:
- The authors refer to experimental studies that show that some neurologic circuits converge in the trigeminal nerve, showing that jaw functioning is inextricably linked with the cervical spine.
- Biomechanically, "the masticatory muscles enter into a synergic or antagonistic relationship with cervical muscles acting as extensors or flexors of the cervical spine. Variations of length and of tonic response in cervical muscles might influence the activity of masticatory muscles."
The authors conclude that future research should investigate not only the role of direct trauma on the TMJ, but also the general "topography of pain and related structures" of the head, face, and spine.
Ciancaglini R, Testa M, Radaelli G. Association of neck pain with symptoms of temporomandibular dysfunction in the general adult population. Scandinavian Journal of Rehabilitation Medicine 1999;31:17-22.