The usefulness of diagnostic imaging for the assessment of pain symptoms in temporomandibular disorders

Abstract

The causes of pain symptoms in the temporomandibular joint (TMJ) and masticatory muscle (MM) regions may not be determined by clinical examination alone. In this review, we document that pain symptoms of the TMJ and MM regions in patients with temporomandibular disorders (TMDs) are associated with computed tomography and magnetic resonance (MR) findings of internal derangement, joint effusion, osteoarthritis, and bone marrow edema. However, it is emphasized that these imaging findings must not be regarded as the unique and dominant factors in defining TMJ pain. High signal intensity and prominent enhancement of the posterior disk attachment on fat saturation T2-weighted imaging and dynamic MR imaging with contrast material are closely correlated with the severity of TMJ pain. Magnetic transfer contrast, MR spectroscopy, diffusion tensor imaging, and ultrasonography findings have helped identify intramuscular edema and contracture as one of the causes of MM pain and fatigue. Recently, changes in brain as detected by functional MR neuroimaging have been associated with changes in the TMJ and MM regions. The thalamus, the primary somatosensory cortex, the insula, and the anterior and mid-cinglate cortices are most frequently associated with TMD pain.

Keywords: Cone beam computed tomography; Diagnostic imaging; Joint pain; Magnetic resonance imaging; Masticatory muscle pain; Temporomandibular disorders.

Figure 1

(A and B) A 47-year-old man with a recent history of left TMJ pain and MM pain. (A) Sagittal T2-weighted closed- (left) and open-mouth (right) MR images show marked effusion (arrows) above the displaced disk (arrowheads) and mandibular condyle. (B) Sagittal dynamic fat-suppressed T1-weighted pre- (left) and postcontrast (right) MR images demonstrate areas of enhancement corresponding to effusion (arrows). TMJ, temporomandibular joint; MM, masseter muscle.

Figure 2

(A and B) A 18-year-old woman with a recent history of right TMJ pain and clicking. (A) Sagittal T1-weighted closed- (left) and open-mouth (right) MR images show anterior disk displacement without reduction (arrows). (B) Sagittal dynamic fat-suppressed T1-weighted pre- (left) and postcontrast (right) MR images demonstrate inhomogeneous prominent enhancement of the posterior disk attachment (arrows). TMJ, temporomandibular joint.

Figure 3

(A and B) Bone marrow edema pattern in the mandibular condyle. (A) Sagittal T1-weighted closed-mouth MR image shows an ill-defined area of abnormal decreased signal in the subchondral bone marrow (arrow). (B) Sagittal T2-weighted closed-mouth MR image demonstrates abnormal increased signal in the corresponding area (arrow) and effusion (arrowheads) in the superior joint space. (C and D) Bone marrow osteonecrosis pattern in the mandibular condyle. (C and D) Both sagittal T1-weighted and T2-weighted closed-mouth MR images show an ill-defined area of abnormal decreased signal in the mandibular bone marrow (arrow) and effusion (arrowheads) in the superior joint space.

Figure 4

(A and B) A 28-year-old man with a recent history of right masseter muscle pain. (A) Axial GRE and (B) MTC-GRE images show less signal loss in the right masseter muscle (arrows). (C and D) A 14-year-old female with left TMJ pain and opening limitation. (C) Axial GRE and (D) MTC-GRE images show less signal loss in the left lateral pterygoid muscle (arrows). GRE, gradient-recalled echo; MTC, magnetization transfer contrast; MM, masseter muscle; TMJ, temporomandibular joint; LPM, lateral pterygoid muscle.

Figure 5

Surface projection of regional brain activity in a TMD patient with right masseter muscle pain when the patient feels the pain by clenching. (A) Frontal view, (B) upper view, (C) right side view, and (D) left side view. The clenching task activated the left sensorimotor cortex, while it did not activate the right one.