Sonographic evaluation of the temporomandibular joints in juvenile idiopathic arthritis☆
Introduction
Juvenile idiopathic arthritis (JIA) is characterized by chronic synovitis and extra-articular manifestations, such as fever, lymphadenopathy, pericarditis, and uveitis. JIA is a chronic inflammatory disease that develops for the age of 16 years and persists for more than 6 weeks [1]. It is diagnosed according to criteria established in 1997 in Durban by the International League of Associations for Rheumatology (ILAR) and revised in 2001 in Edmonton [2]. The temporomandibular joint (TMJ) may be affected by JIA. Temporomandibular diseases (TMDs) such as clicking, crepitation, and disk displacement in patients with JIA have been shown to cause inflammation and degeneration of the condylar heads in the TMJs [3], [4], [5], [6], [7]. TMJ arthritis may not be associated with pain or other clinical signs or symptoms of altered TMJ function, but, it can lead to impaired facial growth, micrognathia, and mandibulofacial alterations such as a convex facial morphology. The possibility of TMJ involvement in children with JIA has to be carefully assessed at disease onset and during follow-up because TMDs are often masked by antirheumatic therapy. In oligoarticular (OA) forms of JIA, TMJ involvement may be overlooked, and symptoms may be absent even during the acute phase of the disease [8].
Ultrasonography (US) has been shown to be an important diagnostic tool, comparable to magnetic resonance imaging (MRI), for the assessment of TMJ involvement in rheumatoid arthritis and psoriatic arthritis [9]. In this study, we evaluated the usefulness of US in the assessment of TMJ involvement and the detect joint effusion (JE) in a cohort of children with JIA.
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Patients and controls
Patients were recruited from the Section of Rheumatology of the Department of Internal Medicine at the University of Florence. We enrolled 68 children (57 girls, 11 boys; median age 11.0 years, age range 9.1–16.0 years) with early-stage JIA (mean duration from onset, 6 ± 2 weeks) that had not been treated.
According to the ILAR revised criteria for the classification of JIA [1], 6 months after onset, 11 out of 68 children had extended oligoarthritis. ANOVA was used to assess correlations between
Results
In all 40 healthy controls, the TMJ capsule was less than 1.4 mm thick. The highest value observed in the controls was 1.38 mm (1 child). Therefore, the 95th percentile was 1.3 mm. The mean thicknesses of the right and left TMJ capsules were not significantly different in controls (1.01 ± 0.16 mm vs. 1.04 ± 0.25 mm, respectively).
In the JIA group, 46 out of 68 patients (68%) presented TMJ JE (bilateral in 16 [35%] cases, unilateral in 30 [65.2%]) (Fig. 1, Fig. 2, respectively). Only 2 (4.3%) out of 46
Discussion
Evaluation of the TMJ is not easy. In JIA, clinical assessment of this joint is insufficient because its involvement is often asymptomatic. Clinical findings must, therefore, be confirmed with imaging studies. MRI is regarded as the gold standard for imaging assessment of the TMJ, but its limited availability and high cost make it unsuitable as a screening or follow-up method [6]. The orthopanogram reveals only late-stage TMJ damage, while computed tomography is not able to visualize the
Conflict of interest statement
The authors have no conflict of interest.
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SIUMB 2008 – Award for the best oral communication presented at the 19th National Congress of the SIUMB.