Delayed temporomandibular joint pain and dysfunction induced by whiplash trauma
From: J Am Dent Assoc, Vol 138, No 8, 1084-1091. 2007
The Quebec Task Force on Whiplash Associated Disorders published a systematic review of the literature on whiplash injuries in 1995 followed by an updated review in 2001. They considered 24 studies of prognosis to be scientifically admissible, one of which focused on the temporomandibular joint (TMJ) but did not include control subjects. Since the updated review, two TMJ related studies have been published. The first study was a controlled follow-up that investigated TMJ pain and dysfunction. It only included patients between the ages of 20 and 35 with signs and symptoms corresponding to whiplash associated disorders grade 11 (that is, a neck complaint of pain, stiffness or tenderness but no physical signs). The patients, therefore, were not representative of the general population that is exposed to whiplash trauma. The second study was population-based and included patients who had been exposed to either an indirect whiplash trauma or a direct trauma to the head. It evaluated the incidence and recovery of reduced or painful jaw movements that began with the car collision but did not account for whether there was TMJ affliction. Impaired and painful jaw movements can be symptoms of TMJ injury, but they also can be associated directly with the neck injury in patients who have whiplash associated disorders. It remains unclear whether a delayed onset of symptoms can occur in TMJs that appear unaffected directly after whiplash trauma.
A study was conducted to enhance knowledge about short-term and long-term TMJ pain, dysfunction or both induced by whiplash trauma. We hypothesized that delayed symptoms frequently develop in the TMJ after whiplash trauma and that the sex of the patient affects the development of posttraumatic symptoms in the TMJ.
The national health insurance in Sweden covers health care costs for patients with whiplash injury, and litigation concerning whiplash-related injuries is rare. If damages are paid, they are small. Hence, damages do not constitute an economic incentive for patients in Sweden to overestimate symptoms after whiplash trauma. This adds credibility to their results, because recovery from whiplash tends to be much faster in jurisdictions operating under a system that does not compensate for pain and suffering. This was demonstrated in a study that found a 54 percent reduction in median time to claim closure after a tort-compensation system for traffic injuries, which included payments for pain and suffering, was changed to a no-fault system, which did not include such payments.
We did not attempt to either attract or reject people with TMJ symptoms, and it is reasonable to consider that their subjects and control subjects reflect a general population that might be exposed to whiplash trauma. This conclusion was supported by the results of a recent population-based study in which the frequency of reported precollision jaw pain equaled the frequency of TMJ pain before the accident in their subjects and control subjects. The conformity in TMJ symptomatology between their subjects before the accident and control subjects was crucial. It was a prerequisite for the long-term comparison between incidence of new posttraumatic TMJ symptoms in the subjects after whiplash trauma and concurrent development of TMJ symptoms (that is, the natural course) in the control subjects. We also noted conformity between groups in that neither subjects nor control subjects had received TMJ treatment, although it was spontaneously requested by 12 percent of the subjects at follow-up. The true number of patients in need of TMJ treatment most likely was higher, considering the increase in pain intensity and the increase of TMJ symptoms, mostly painful locking, which they reported to be the main complaint.
It is plausible that the subjects’ estimations of pain and pain intensity would have been even higher had there not been a more extensive use of analgesics in the subject’s group than in the control subjects’ group. Conversely, pain’s adverse effect on sleep and daily activities might enhance a patient’s perception of pain and pain intensity. Other factors that might have influenced the outcome of TMJ pain and pain intensity are psychosocial dysfunction and psychological factors such as depression and anxiety. Depression symptoms are common after whiplash trauma, and neck pain intensity directly after whiplash trauma is a prognostic factor for depression and anxiety within the two following years. We have not assessed psychological and psychosocial illnesses in their study, and further research is needed to evaluate their prognostic impact on TMJ symptoms after whiplash trauma.
Incidence of posttraumatic TMJ symptoms. Their hypothesis that delayed TMJ symptoms frequently appear after whiplash trauma was verified. After one full year, we found a significant difference between subjects and control subjects in that one in three of the primarily asymptomatic subjects but only one in 14 matched control subjects had developed TMJ symptoms including dysfunction, pain or both. This contradicts the results of a controlled, prospective study that reported no significant difference in the frequency of TMJ symptoms between subjects and control subjects directly after the accident or after six months. The disparity in results between studies can be explained by their inclusion of patients with signs and symptoms corresponding to only whiplash associated disorders grade 1, while their subjects had signs and symptoms corresponding to whiplash associated disorders grades 1 through 3. Furthermore, they excluded patients younger than 20 years and older than 35 years from their study, while we did not have an age-related exclusion criterion. The resulting age range of 17 to 56 years in their study represented a typical population exposed to whiplash trauma.
Their follow-up findings also contradicted the results of a prospective, but uncontrolled, study that reported no increase of joint symptoms one year after trauma compared with the symptoms after the accident. The difference likely can be explained by a deviant range of symptoms in their patient population compared with the general population. The authors found TMJ clicking in only 1 percent of their patients, while there are studies that reported a prevalence between 15 and 44 percent in general populations with various age ranges. At the inceptive examination, the frequencies of TMJ clicking in their subjects and control subjects were in line with those in general populations.
TMJ symptoms as main complaint. One in five subjects reported that TMJ symptoms were their main complaint one full year after the accident. This was quadruple the number of subjects reporting TMJ symptoms as their main complaint directly after the accident, and the increase was found in female subjects. Neck related symptoms after whiplash trauma are more common in women than in men. One hypothesis for this is that given the same head size, women have less neck musculature mass than do men, which makes them more susceptible to this type of trauma. As with the neck, their results point to the TMJ being more vulnerable in women than in men because the significant increase in the number of patients reporting TMJ symptoms as the main complaint was attributed to women.
In their study at the inceptive examination, subjects reported having TMJ pain significantly more frequently than did control subjects, which is in line with a study conducted two weeks after whiplash trauma. At follow-up in their study, one in three subjects reported having TMJ pain, which was five times more frequent than in control subjects and was contrary to the reported frequency of pain before the inceptive examination (no difference between subjects and control subjects). TMJ pain intensity increased in subjects from the inceptive examination to follow-up, but the number of subjects was not large enough to yield sufficient statistical power. Frequency of TMJ pain increased significantly from the inceptive examination to follow-up for female subjects, which also was the case for TMJ symptoms’ being the main complaint. The majority of subjects with TMJ symptoms as their main complaint at follow-up reported the onset of new symptoms that were consistent with painful nonreducing TMJ disk displacement.
