Laboratory Studies
No laboratory studies are specifically indicated to rule in temporomandibular joint (TMJ) syndrome; however, appropriate laboratory samples may be drawn to help rule out other disorders, as follows:
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Complete blood count (CBC), if infection is suspected
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Calcium, phosphate, or alkaline phosphatase, for possible bone disease
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Uric acid if gout is suspected
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Serum creatine and creatine phosphokinase, indicators of muscle disease
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Erythrocyte sedimentation rate if temporal arteritis is suspected
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Rheumatoid factor if rheumatoid arthritis is suspected.
Imaging Studies
Imaging studies generally are not indicated in the emergency department, unless a fracture is suspected. Considerations are as follows:
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Panorex (a radiograph that provides a full view of the upper and lower jaws, teeth, TMJs, and sinuses) may show a fracture, evidence of osteoarthritis, or displacement of the articular disk; Ahn et al demonstrated that panorex films can also be effective in evaluating patients with internal derangement of the TMJ. [9]
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Plain radiographs may demonstrate resting and hinge movement of the TMJ.
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A computed tomography (CT) scan may reveal greater detail of bones than radiographs alone.
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Magnetic resonance imaging (MRI) is the test of choice when looking for disk displacement or pathology. Although central sagittal scans alone are often used, Litko-Rola et al found that multisection evaluation with both sagittal and coronal scans had significantly higher sensitivity for evaluation of TMJ internal derangement. In their study of 382 TMJs in 191 patients with disc displacement, normal disc position was identified in 148 TMJs (38.7%) on central oblique sagittal scans, compared with 89 TMJs (23.3%) on all oblique sagittal and coronal scans (P < 0.001). [10]
For more information, see Temporomandibular Joint (TMJ) Meniscus Abnormality Imaging.
Diagnostic Nerve Block
The auriculotemporal branch of the trigeminal nerve provides the sensory innervation of the TMJ. A diagnostic nerve block of the auriculotemporal nerve can be helpful in differentiating whether the unilateral orofacial pain originates in the TMJ capsule. [11]
To perform a diagnostic anesthesia block, use a 25- to 30-gauge needle and inject 0.5 mL of short-acting anesthetic about 0.5 inches below the skin just inferior and lateral to the mandibular condyle. If the patient does not experience pain relief with the nerve block, consider other causes of the orofacial pain.
