A single-blind randomized controlled trial of ultrasound-guided Canggui Tanxue needling technique for contractural facial synkinesis

BACKGROUND: Facial spastic synkinesis (FSS) is a disabling sequela of facial nerve palsy, with current treatments limited by transient efficacy, severe side effects, poor precision, and lack of quantifiable targets/objective evaluation. This study used ultrasound shear wave elastography combined with Canggui Tanxue needling to precisely locate lesioned muscles, exploring a safer, more effective targeted strategy to address the gap of insufficient precision and quantitative evidence in clinical practice. METHODS: A single-blind randomized controlled trial was conducted at Chongqing Traditional Chinese Medicine Hospital's Acupuncture Department (June 2022 to May 2023), enrolling 64 FSS patients randomized into an ultrasound-guided group (n = 31) and a control group (n = 33). The former received Canggui Tanxue needling at hypertonic muscles (Young modulus > 10 kPa) under real-time shear wave elastography, the latter received traditional syndrome differentiation-based acupuncture. Both groups had 6 sessions (twice weekly for 3 weeks). Outcome measures included primary (Young modulus of target muscles) and secondary (House-Brackmann grading, Facial Disability Index, and total effective rate) indicators. SPSS 26.0 was used for statistical analysis. RESULTS: A total of 64 patients aged 27 to 66 years were enrolled, including 25 males (39.06%) and 39 females (60.94%). Baseline characteristics were comparable between groups (P > .05). Post-intervention, the ultrasound-guided group had significantly larger reductions in Young modulus of depressor anguli oris (3.00 vs 1.10 kPa) and levator labii superioris (5.60 vs 1.00 kPa) versus controls (P < .001). It also showed superior facial nerve recovery (House-Brackmann grading: P = .013), a higher total effective rate (87.1% vs 42.4%, P < .001), and greater improvement in physical function scores (74.84 ± 8.42 vs 68.94 ± 13.68, P = .04). Psychosocial function scores decreased in both groups (P = .92). Only 2 mild subcutaneous hematomas occurred in the ultrasound-guided group, confirming good safety. CONCLUSIONS: Ultrasound-guided Canggui Tanxue needling precisely targets hypertonic muscles, reduces pathological tension, improves FSS patients' facial function, and is safe, offering an effective targeted strategy. Clinical promotion of this precise acupuncture technology is recommended, especially for late-stage facial nerve palsy patients with abnormal muscle tension. Future studies should extend follow-up to assess long-term efficacy/recurrence and combine neurophysiological/multimodal imaging to clarify its mechanism.