Juvenile idiopathic arthritis

Four-year-old girl presented with painful knee swelling that had continued for eight weeks (erthrocyte sedimentation rate [ESR] = 45 mm/h; C-reactive protein [CRP] = 1.2 mg/dL). Juvenile idiopathic arthritis was diagnosed after exclusion of other causes.

The patient was treated successfully with nonsteroidal anti-inflammatory drugs and subcutaneous methotrexate, leading to remission of the knee swelling. Routine contrast-enhanced MRI of the asymptomatic temporomandibular joints (TMJ) was subsequently performed, when the patient was five years old.

FINDINGS

Contrast-enhanced T1-weighted MRI with fat saturation revealed bilateral synovial thickening and enhancement (Figure 1, arrows). Bilateral TMJ arthritis was diagnosed despite the absence of clinical findings. No signs of early degenerative changes were observed.

To prevent further degenerative changes, bilateral MR-guided steroid injection (40 mg triamcinolone acetonide with gadolinium-DTPA 1:200 for each TMJ) was performed in a 1.5T open-bore MRI system (Magnetom Espree, Siemens) after discussion of other treatment options. MR-compatible needle (MR Chiba, Somatex) was placed in the dorsal fossa of the left TMJ under MR fluoroscopy guidance using a T1-weighted turbo spin-echo sequence (Figure 2. Needle tip highlighted with a dashed arrow; solid arrows mark the mandibular condyle).

Sagittal postinterventional control MRI (T1-weighting with fat saturation) demonstrates the homogeneous intra-articular distribution of the injected material (Figure 3). Follow-up contrast-enhanced MRI examinations after six and 24 weeks show complete remission of the bilateral synovial thickening and enhancement without any additional systemic treatment (Figures 4 and 5).

DISCUSSION

TMJ arthritis is common in patients with juvenile idiopathic arthritis and is often asymptomatic. It can cause long-term complications including pain and restricted mouth opening.¹ Treatment with intra-articular corticosteroids has been shown to be effective, safe, and associated with minimal side effects.² Image-guided techniques should be applied when attempting intra-articular injection, owing to the anatomic location of the TMJ, to ensure correct needle placement. Techniques that do not involve ionizing radiation are preferred given the young age of patients. We have found MRI to be a safe and effective way of guiding intra-articular corticosteroid injections of the TMJ in children with juvenile idiopathic arthritis.

In the case described here, TMJ arthritis was diagnosed and treated before any permanent, degenerative changes occurred.

Case submitted by Dr. Christoph Thomas, Dr. Stephan Clasen, Dr. Marius Horger, Prof. Claus Classen, and Prof. Philippe Pereria of the department of diagnostic and interventional radiology, University of Tübingen, Germany; Dr. Jan Fritz, department of pediatric rheumatology, University of Tübingen; and Dr. Nicolay Tzaribatchev of Johns Hopkins University Clinic, Baltimore, Maryland, U.S.