The Role of Ultrasound in Temporomandibular Joint Disorders: An Update and Future Perspectives

Abstract

Temporomandibular joint (TMJ) disorder is the second most common chronic pain condition affecting the general population after back pain. It encompasses a complex set of conditions, manifesting with jaw pain and limitation in mouth opening, influencing chewing, eating, speaking, and facial expression. TMJ dysfunction could be related to mechanical abnormalities or underlying inflammatory arthropathies, such as rheumatoid arthritis (RA) or juvenile idiopathic arthritis (JIA). TMJ exhibits a complex anatomy, and thus a thorough investigation is required to detect the TMJ abnormalities. Importantly, TMJ involvement can be completely asymptomatic during the early stages of the disease, showing no clinically detectable signs, exposing patients to delayed diagnosis, and progressive irreversible condylar damage. For the prevention of JIA complications, early diagnosis is therefore essential. Currently, magnetic resonance imaging (MRI) is described in the literature as the gold standard method to evaluate TMJ. However, it is a high-cost procedure, not available in all centers, and requires a long time for image acquisition, which could represent a problem notably in the pediatric population. It also suffers restricted usage in patients with claustrophobia. Ultrasonography (US) has emerged in recent years as an alternative diagnostic method, as it is less expensive, not invasive, and does not demand special facilities. In this narrative review, we will investigate the power of US in TMJ disorders based on the most relevant literature data, from an early screening of TMJ changes to differential diagnosis and monitoring. We then propose a potential algorithm to optimize the management of TMJ pathology, questioning what would be the role of ultrasonographic study.

Comparison between ultrasound and magnetic resonance imaging of the temporomandibular joint in juvenile idiopathic arthritis: A systematic review

“…8,45,46 US can also be suggested as useful examination tool due to its widespread accessibility, cost-effectiveness, real-time quick dynamic and direct assessment and higher paediatric patient tolerance with no need of sedation or use of contrast, the potential utility in detecting both osteochondral and soft-tissue changes during imageguided TMJ procedures and for monitoring the course of a pathological condition or treatment. 43,47 However, besides the US limitations there are no reference values of lateral condylar changes, synovial or capsular-condylar thickness or joint effusion neither an accepted scoring system of these TMJ measurements. [48][49][50] The correlation between US and contrast-enhanced MRI in children with JIA is positive and evaluate as 'moderate' when considering the acute arthritis visualised as synovial enhancement or increased capsular and lateral periarticular space.…”

“…36,46 The disc position was not checked in any of the included studies probably because previous outcomes on patients with TMD were confusing. Only a few authors observed some abnormalities in the disc-condyle relationship through US, 43,[51][52][53][54][55] however, it is overall accepted that US is not useful neither accurate to diagnose TMJ disc displacements 36,43,[56][57][58][59][60] when a discrimination between displacement with or without reduction is needed. 43,54 About the detection of intraarticular effusion in the TMJ area, Manfredini et al 54 stated that US remains potentially useful as an alternative imaging technique with a good accuracy, 48 even though the challenging analysis of TMJ capsular width is in only 2 mm.…”

“…61 This is in agreement with other authors reporting good performance of US in assessing joint effusion and condylar erosion. 36,43,51,53,57,62,63 Clinical assessment of TMJs was carry out in four studies. 16,34,35,38 In particular, it was detected the MIO as sign of TMJ involvement.…”

“…Currently, MRI is considered the gold standard technique for TMJ assessment, 8,39 for its high sensitivity and specificity in identifying both acute and chronic pathologies as well as arthritic sequelae. 42,43 In particular, the most recent EULAR guidelines for JIA management recommend the MRI for the diagnosis and follow-up of TMJ. 43,44 Specifically, acute findings include joint effusion, synovial enhancement and thickening and bone marrow edema.…”

“…42,43 In particular, the most recent EULAR guidelines for JIA management recommend the MRI for the diagnosis and follow-up of TMJ. 43,44 Specifically, acute findings include joint effusion, synovial enhancement and thickening and bone marrow edema. Osteochondral and other chronic changes include pannus formation, condylar flattening, bone erosions, disk abnormalities and hypertrophic bone formation.…”