Evaluation of the ultrasonography-guidance for botulinum toxin type a injection into lateral pterygoid muscle in patients with TMJ anterior disc displacement with reduction.

Anterior disc displacement with reduction (ADDwR) is a common temporomandibular joint disorder associated with pain, joint sounds, and limited jaw movement. Conservative treatments are considered first-line but often yield unsatisfactory results. Botulinum toxin type A (BTX-A) injection into the lateral pterygoid muscle (LPM) offers a minimally invasive alternative, and ultrasonography enhances safety and accuracy through real-time, radiation-free guidance. This single-arm clinical trial included ten patients (20 TMJs), aged 19-38 years, diagnosed with ADDwR. Each patient received 25 units of BTX-A into the LPM under ultrasound guidance. Clinical outcomes, including pain (NPRS), clicking sound, maximum interincisal opening (MIO), and lateral excursion of the mandible, were assessed at 2, 6, 12, and 24 weeks. MRI was performed at baseline and 12 weeks to evaluate disc position, while Fonseca's questionnaire was applied preoperatively and at 24 weeks. Significant improvements were observed in pain, clicking, MIO, and lateral excursion, with MRI confirming improved disc position at 12 weeks and Fonseca scores demonstrating marked improvement at 24 weeks. The findings suggest that ultrasound-guided BTX-A injection into the LPM is a safe and effective treatment for ADDwR, enhancing joint function and symptom relief, although larger randomized studies are recommended.