Clinical effectiveness of thread-embedding acupuncture in the treatment of Bell's palsy sequelae: A randomized, patient-assessor-blinded, controlled, clinical trial

Bell's palsy, also known as idiopathic facial palsy, affects the muscles responsible for facial expression and may leave lasting sequelae in approximately 30% of patients. This randomized controlled trial investigated the efficacy of thread-embedding acupuncture (TEA) as an additional treatment for patients with Bell's palsy sequelae persisting for more than three months. TEA is an innovative technique that involves the insertion and embedding of absorbable materials such as polydioxanone into specific acupuncture points, maintaining the therapeutic effect for prolonged periods through mechanical and chemical reactions of the embedded thread. The study was conducted at Kyung Hee University Hospital in Gangdong, Seoul, with 56 participants randomized into two parallel groups.

The experimental group received true TEA once a week for eight weeks, while the control group received sham TEA (with threads removed). Both groups also received traditional acupuncture twice a week as concomitant treatment. The double-blinded design ensured that neither the patients nor the assessors knew which treatment was being administered. TEA was applied at ten specific points on the face (ST-5→ST-6, ST-4→ST-7, ST-4→LI-20, LI-20→BL-1, GB-3→LI-20, ST-7→LI-20, SI-18→LI-20) by physicians specialized in Korean medicine with more than seven years of experience.

The procedure involved oblique needle insertion at angles of 10-20 degrees up to 4 cm depth in the superficial musculoaponeurotic system layer. The primary outcome was the change in the Facial Disability Index (FDI) from baseline to eight weeks. The results showed significant improvement in the physical aspect of the FDI in the TEA group compared with the control group after eight weeks (p = 0.048). There was also a significant difference in the lip length index at four weeks, favoring the TEA group.

Both groups showed significant improvements over time in various parameters, including FDI social and physical scores, the Facial Nerve Grading System 2.0, and the Sunnybrook Facial Grading System. Facial stiffness improved significantly only in the TEA group, and the House-Brackmann grade also showed superior improvement in this group. In terms of safety, no significant adverse events were reported, except for minor bruising at the thread implantation site. Laboratory tests and vital signs showed no clinically significant changes.

The adherence rate was high, with 89.28% of participants completing the study. Clinical implications suggest that, although TEA may offer some additional benefits, especially for physical discomfort and facial stiffness, its efficacy as an add-on treatment to traditional acupuncture has not been conclusively demonstrated for all aspects of Bell's palsy sequelae. The study is pioneering as the first randomized controlled trial to investigate TEA for Bell's palsy sequelae, providing valuable information about selection criteria, sample sizes, and outcome measures for future studies. Limitations include the difficulty of isolating the specific effects of TEA due to concomitant treatment with traditional acupuncture, the lack of long-term follow-up beyond eight weeks, and significant baseline differences in facial stiffness scores between groups.