Magnetic resonance imaging of temporomandibular joint in juvenile idiopathic arthritis

Abstract

Background: Juvenile Idiopathic Arthritis (JIA) is the most common autoimmune inflammatory synovial arthritis causing wide range of disability in children. The involvement of temporo-mandibular joint (TMJ) in JIA varies ranging from 17% to 87%. Unlike other synovial joints, the TM joint is particularly vulnerable to inflammatory damage as the mandibular growth plate is superficial. JIA is a clinical diagnosis and is characterized by synovial hyperplasia and inflammation leading to joint effusion. TMJ involvement is clinically difficult to assess and often goes untreated. Children with TMJ arthritis have mastication dysfunction and pain. Delayed detection and treatment leads to abnormalities like micrognathia, jaw deformity, facial dysmorphism and chewing problems. MRI is the most sensitive modality to diagnose synovitis and involvement of TMJ in children of JIA.Methods: A cross-sectional observational study was undertaken in 30 children diagnosed as JIA as per ILAE criteria. They were evaluated clinically followed by contrast enhanced MRI for evidence of TMJ arthritis.Results: Of the 60 joints evaluated, clinical involvement was found in 18 joints (10 patients). 12(66.7%) out of them had MRI changes. 3(7.1%) joints out of 42 asymptomatic joints had MRI changes. 13 joints had synovial hypertrophy, 8 joints showed bone erosions. Bone marrow edema was seen in 2 joints, with no evidence of cartilage involvement in any joint. The sensitivity, specificity, PPV and NPV of clinical examination to diagnose TMJ arthritis as compared to MRI was 80.0%, 86.7%, 66.7% and 92.7% respectively.Conclusions: With paucity of clinical signs and symptoms, early involvement of TMJ arthritis in children of JIA can be detected by MRI to prevent long term disability in patients.