Abstract
The contour of the neck and shoulder is defined by the trapezius muscle (TM). Beyond facial procedures, botulinum toxin A (BoNT-A) injections has been increasingly adopted to create a smooth shoulder line. Several studies described the intramuscular nerve branching and the pattern of perforating branch of the accessory nerve in the trapezius muscle, providing essential information for botulinum neurotoxin injection. To this date, research groups seldom perform clinical investigations, especially randomized controlled trials, that demonstrates whether BoNT-A injections using the nerve distribution method for aesthetic purposes is more effective. Patients met the criteria for inclusion were randomized to either the Nerve Distribution group (ND group) or control group. Control group patients received injection using the conventional method while ND group patients received the nerve distribution method. Photographic and ultrasonographic evaluations were carried out at baseline, one month, three months, and six months after the procedure. Patients were also required to complete a questionnaire to evaluate their feedbacks to the injection. After screening, 30 healthy young Chinese women were included. At one-month follow-up, no statistically significant difference was observed between the two methods. At the three-month follow-up, the reduction of the TM thickness for the ND group (0.21 ± 0.09 cm) was more than that for the control group (0.27 ± 0.08 cm), with p = 0.047*. Similar differences were observed for the reduction of the shoulder area proportion (p = 0.031*) and the shoulder angle (p = 0.035*). At the six-month follow-up, the reduction in TM thickness in the ND group (0.2 ± 0.09 cm) was more than that of the control group (0.28 ± 0.06 cm), with p = 0.041*. The global aesthetic improvement scale feedbacks of the two methods showed no significant difference (3.4 ± 0.71 vs 3.8 ± 0.91, p = 0.207). The patients did not experience severe side effects. Compared to the conventional injection method, the nerve distribution method is more effective in reducing the trapezius muscle thickness, shoulder area proportion, and shoulder angle at three months, and shows longer lasting effects. The results of this study introduce unique insights into the design and tailoring of treatment protocols for shoulder-line contouring using BoNT-A.
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The work was supported by National High Level Hospital Clinical Research Funding, grant No. 2022-PUMCH-B-041, 2022-PUMCH-A-210 and 2022-PUMCH-A-025.
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All authors have read and approved the final manuscript. LW, MZ, and TL performed the research. JH, NY and XL designed and improved the research study. YC and WZ contributed essential reagents or tools and analyzed the data. LW wrote the paper.
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Video of injection technique (MP4 4549 KB)
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Ultrasonic images were taken at Point D. The upper segment of the yellow dotted line represented thickness of the subcutaneous tissue; lower segment represented thickness of the TM.(JPG 237 KB)
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Comparison of the reduction (from baseline) of the TM thickness of each point and the anterior border of the TM at each follow-up visit between the conventional and the nerve distribution method. NS stands for non-significant. The asterisk (“*”) stands for significant result based on 95% confident intervals. (DOCX 20 KB)
266_2023_3662_MOESM4_ESM.docx
Comparison of the ratio change (from baseline) of the TM thickness of each point and the anterior border of the TM at each follow-up visit between the conventional and the nerve distribution method. NS stands for non-significant. The asterisk (“*”) stands for significant result based on 95% confident intervals. (DOCX 20 KB)
266_2023_3662_MOESM5_ESM.docx
Comparison of the ratio change (from baseline) of the TM thickness, shoulder area proportions and shoulder angle at each follow-up visit between the conventional and the nerve distribution method. NS stands for non-significant. The asterisk (“*”) stands for significant result based on 95% confident intervals. (DOCX 16 KB)
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Wang, L., Zhang, M., Li, T. et al. Nerve Distribution Method is Superior to the Conventional Method in BoNT-A Treatment of Trapezius Hypertrophy: A Randomized Controlled Trial. Aesth Plast Surg 48, 1210–1217 (2024). https://doi.org/10.1007/s00266-023-03662-y
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DOI: https://doi.org/10.1007/s00266-023-03662-y