Auto Injuries and Temporomandibular Joint Disorder
Clinicians for years have seen a relationship between car crashes and temporomandibular joint disorder (TMD), but the exact mechanism of injury has yet to be discovered. Some researchers have postulated the existence of "mandibular whiplash"—or a dramatic opening of the jaw during a collision that could cause damage to the TMJ. More recent studies1 have discredited this theory, and experimental collisions involving human test subjects2 have failed to show any evidence of excessive jaw motion during collisions at speeds of 7 mph.
There does, however, seem to be some kind of relationship between motor vehicle accidents and TMD, and something more than just referred pain from damaged soft-tissues in the posterior neck, as some have suggested.1 Other current studies have reported objective tissue damage to the TMJ in patients with a history of whiplash injury. Goldberg et al reported that post-traumatic TMD sufferers reported higher levels of pain in the jaw musculature and showed similarities to patients with mild traumatic brain injury.3 A study by Garcia and Arrington4 found that whiplash patients were significantly more likely to have TMJ changes evident on MRI, and concluded that TMJ tissue damage should be evaluated in all whiplash patients. (Article 2 is reviewed in Low Velocity Whiplash Biomechanics, and articles 3 & 4 are reviewed in the Bound Volume 1 of the Soft-Tissue Review.)
Two new studies have just recently been published that add to our knowledge of this complex issue.
In first study,5 researchers examined 42 adults who were suffering from chronic post-traumatic headache of at least 3 months duration. All patients had suffered trauma to the head and/or neck in a motor vehicle accident, none had a clinically significant history of headache before the injury, and no patient had lost consciousness for more than 1 hour. (The average loss of consciousness was 20.5 minutes, but 81% of the patients had not lost consciousness at all.) 69% of the patients were involved in active litigation regarding their injury. All patients participated by completing a questionnaire, an interview, a physical assessment, and a neuropsychological assessment.
After all of the data was collected, the researchers found that more than 40% of the patients had 13 or more positive signs that would indicate the presence of TMD. "...the results suggest that TM dysfunction is a common concomitant of chronic post-traumatic headache and support the relevance of examination for TM dysfunction in such patients." The authors also found that only 10% of these patients had previously been evaluated for TMD.
The second study6 compared 50 patients with trauma-related TMD to 50 patients with nontrauma-related TMD. The researchers assessed each of these patients in regard to pain levels, TMJ signs and symptoms, clinical examination findings, and diagnoses.
The researchers found that the trauma-related TMD patients reported higher levels of facial pain, more severe headaches, greater neck pain/symptoms, and more sleep disturbance than did patients with nontrauma-related TMD pain.
Ear-related symptoms were also more common in the trauma patients—"When 'ear-related symptoms' were grouped together, 50% of the trauma patients had one or more reported symptoms of dizziness, tinnitus, a plugged sensation of the ears, earache, or a hearing problem, compared to 28% of the nontrauma group."
"The nontrauma group had more complaints and examination findings of TMJ crepitus and higher self-reports of parafunctional jaw habits. No differences in occlusional parameters were noted between trauma and nontrauma patients. The remainder of the presenting signs, symptoms, and TMD diagnoses showed no between-group differences."
- Christensen LV, McKay DC. Reflex jaw motions and jaw stiffness pertaining to whiplash injury of the neck. Journal of Craniomandibular Practice 1997;15(3):242-260.
- McConnell WE, Howard RP, Van Poppel J, et al. Human head and neck kinematics after low-velocity rear-end impacts: understanding whiplash. SAE 952724.
- Goldberg MB, Mock D, Ichise M, et al. Neuropsychologic deficits and clinical features of posstraumatic temporomandibular joint diosrders. Journal of Orofacial Pain 1996;10(2):126-140.
- Garcia R, Arrington JA. The relationship between cervical whiplash and temporomandibular joint injuries: an MRI study. The Journal of Craniomandibular Practice 1996;14(3):233-239.
- Duckro PN, Chibnall JT, Greenberg MS, et al. Prevalence of temporomandibular dysfunction in chronic post-traumatic headache patients. Headache Quarterly 1997;8(3):228-233.
- Kolbinson DA, Epstein JB, Senthilselvan A, Burgess JA. A comparison of TMD patients with or without prior motor vehicle accident involvement: initial signs, symptoms, and diagnostic characteristics. Journal of Orofacial Pain 1997;11(3):206-214.