Early detection and follow-up of morphological alterations of temporomandibular joint in Juvenile Idiopathic Arthritis: High-resolution ultrasound

Introduction: Ultrasonography could be an helpful screening method for the detection of TMJ involvement in children with JIA. It can be used and well tolerated even in very young children (2 years) without sedation or radiation risk. Objectives: The aim of this work was to evaluate the usefulness of high-resolution ultrasound (US) in the early detection of temporomandibular joint (TMJ) alterations and to show normal and pathological imaging appearance of the TMJ in patients with Juvenile Idiopathic Arthritis (JIA). Although TMJ arthritis in JIA is frequently asymptomatic, the TMJ is particularly susceptible to damage. The TMJ is commonly involved in JIA and can lead to malocclusion, condylar alterations, facial deformity and restricted mouth opening. Methods: High-resolution US examinations were performed in 130 patients with JIA. 34 patients (34%) had normal US appearance on both side. The sonograms were done using General Electric LOGIQ E9 equipment using real-time linear-array transducers with variable frequencies (9-18 MHz) by an experienced radiologist. Longitudinal and transverse view images were obtained. Dynamic video clips demonstrated condylar translation from “closed mouth” position to “open mouth” position. The movements can be recorded and compared between the left and the right side. Color Doppler US images furnish diagnostic information regarding hyperemia and synovial vascularity, thus allowed to study vascular signals in the soft tissues around the TMJ. Each joint was analyzed with regard to condylar irregularity, capsular thickness (effusion/synovial thickness), condylar disk dislocation, vascular increasing on Color-Doppler examination and symmetry in condylar translation between open- and closed-mouth position. Results: In our clinical cases capsular thickness, enlargement of the intra-articular space, joint effusion, osteophytes, irregular condyle shape, disc displacement, erosions, increased color Doppler signals were detected. Limitations were especially related to the scarce accessibility of the medial part of the TMJ structures, and the need for trained operators. An important advantage especially in the case of children is that US examination does not require conscious sedation or general anesthesia. Conclusions: The prevalence of TMJ involvement in patients with JIA varies widely (17–87%) and it is often asymptomatic even during the acute phase therefore consequently overlooked. Since inflammation in the TMJ can lead to joint deformity, early diagnosis and treatment of TMJ arthritis are particularly important. High-resolution US could be suggested as a screening tool to detect morphological alterations at an early stage of the JIA. Utilization of high-resolution US for TMJ disorder diagnosis in patients with JIA should increase due to relatively low costs and non-invasivity of the method, moreover it is a nonionizing tool. High-resolution US should be used for detecting inflammatory lesions before permanent TMJ destruction occurs, and monitoring disease progression and treatment response for a more effective therapy.