Temporomandibular Joint Disorders and the Role of Pain Physicians
The temporomandibular joint (TMJ) is important to activities we perform on a daily basis. It facilitates complex movements necessary for chewing, swallowing, and speaking; as such, pain and decreased mobility related to TMJ disorders can significantly impair a patient’s quality of life. Affected patients usually seek initial medical care from dentists, family practitioners, internists, or otolaryngologists. Prompt recognition may be challenging, and even with a diagnosis, pain related to TMJ pathology may be difficult to manage appropriately. Many patients are eventually referred to chronic pain physicians, and our expertise here is crucial.
“Pain related to TMJ pathology may be difficult to manage appropriately. Many patients are eventually referred to chronic pain physicians, and our expertise here is crucial.”
TMJ disorders (TMD) encompass a wide range of joint-related dysfunction. Collectively, they are fairly common and affect up to 25% of the population. TMD affects females to a disproportionately greater degree, with studies reporting female to male ratios ranging from 2:1 to 8:1. Only a small percentage of affected patients seek treatment.
Understanding the joint’s anatomy is imperative for a correct diagnosis that eliminates differential diagnoses. The TMJ is a diarthroidal hinge joint formed by the temporal bone and the mandible. The mandibular fossa and articular tubercle of the temporal bone are the superior articular surfaces that meet the posterior, cephalad projection of the mandible, called its condyle, at this synovial joint. An articular disc lies between the two fibrocartilaginous surfaces and divides the joint into two cavities (Figure 1).
Pain is a common presentation of TMD and can occur anywhere along the distribution of the trigeminal nerve. It may be well localized around the TMJ but is often perceived along the inferior line of the jaw, within surrounding muscles involved in motion of the jaw (including the masseter and temporalis), in the ear, in the neck, and as far posterior as the suboccipital region. Other symptoms include restriction of jaw movement or locking, bothersome sounds such as clicking or crepitus, difficulty chewing or swallowing, and facial swelling. On physical examination, evaluate the muscles and soft tissues surrounding the TMJ, occlusal position, mandibular range of movement, and posture of the jaw, head, and neck.
Computer tomography and magnetic resonance imaging can definitively diagnose many conditions affecting the TMJ. Examples include joint effusions, capsular disruptions, degenerative changes, and occlusal abnormalities. Imaging studies can also detect the presence of other diagnoses that may mimic TMD, such as aural and dental inflammatory conditions, temporal arteritis, mandibular diseases, and muscular injury.
The clinical picture is not always straightforward. Given the intricate anatomy and range of function of the TMJ, and the fact that pathology of so many nearby structures may have a contributing etiology, determining the best approach to pain management is challenging. Pain specialists are being referred increasing numbers of patients with TMJ-related issues.
The Research Diagnostic Criteria for Temporomandibular Disorders protocol presents a reliable diagnostic algorithm to which physicians should refer., The classification subdivides etiologies into myogenic, arthrogenic, disc displacement, and cervical spine groups of disease. It incorporates pain screening tools, symptom questionnaires (useful for detailed history taking), diagnostic criteria checkpoints, and a behavioral checklist, which can help identify social stressors. It is a very useful tool for diagnosis and planning of treatment.
Noninvasive pain management modalities should be the first approach. Options include physical therapy, pharmacologic agents, and splints. Modification of emotional stressors that may aggravate symptoms through nocturnal grinding is important and requires active patient participation. Patients may be referred to mental health providers to assist with care. Physical therapy and transcutaneous electrical nerve stimulation may help improve the TMJ’s range of motion. Nonsteroidal anti-inflammatory drugs reduce inflammation and associated pain. Muscle relaxants can be beneficial for treating any spasmodic contribution to pain. Tricyclic antidepressants are useful for treating bruxism and sleeplessness related to symptoms. Occlusal splints stabilize the TMJ by repositioning the mandibular condyles into centric relation and facilitate relaxation of muscles in spasm.
Figure 2: Ultrasound image of temporomandibular joint. 2A: Transverse section; 2B: Longitudinal section; Inlays: guide for linear ultrasound probe placement for examination.
AD, articular disc; MC, mandibular condyle; TB, temporal bone; TM, mandibular fossa of temporal bone
Surgical intervention may be necessary if conservative measures are inadequate. Arthrocentesis and drainage of debris and inflammatory collections are both diagnostic and therapeutic. Sodium hyaluronate and corticosteroid intra-articular injections may benefit patients with osteoarthritis in the joint (Figure 2). Injections of botulinum toxin A into surrounding musculature may help in relieving the pain of chewing. Additionally, arthroscopic surgery, arthrotomy, modified condylectomy, discectomy, or total joint replacement may be indicated.
Pain physicians should be familiar with all the diagnosis and management of TMD-related pain. Patients with TMD often seek medical care before presenting to a pain physician and may be frustrated with the challenges of diagnosis and symptom control. It is important that we elicit the pertinent history and physical examination findings to eliminate other differential diagnoses. We should be able to offer patients with TMD excellent care with a good understanding of the etiology and appropriate treatment for this group of diseases. It is our responsibility to coordinate a comprehensive treatment plan that often necessitates a multidisciplinary approach to manage this painful condition.
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