Efficacy of Botulinum Toxin in the Treatment of Facial and Cervical Hypertrophic Scar: A Meta-Analysis.

[OBJECTIVE] Maxillofacial-neck hyperplastic scars have long been a persistent concern among individuals in both Western and Eastern countries. These scars exhibit rapid growth within 3-6 months following wound healing, subsequently receding at a slower pace, leading to skin redness, tension, and potential itching. The lack of comprehensive understanding regarding the formation mechanism and biological attributes of these scars has made them a prominent subject of research both domestically and internationally.

[METHODS] Research data from 2010 to 2023 was selected, and relevant literature on the efficacy of botulinum toxin in the treatment of facial and neck hypertrophic scars was searched until August 2023. The literature on the incidence of facial-neck hypertrophic scars included in PubMed, the Cochrane Library, EMbase, and Web of Science was searched. Two researchers independently screened and extracted the data according to strict inclusion and exclusion criteria.Risk bias in Review Manager 5.4, provided by the Cochrane Collaboration, was used for methodological quality assessment and meta-analysis of the included literature. In case of any disagreement, the decision shall be made through consultation with the third party. Scar width, patient satisfaction, and visual analogue scale (VAS) were evaluated. Weighted mean difference (WMD), odds ratio (OR), and 95% confidence interval (95%CI) were used for evaluation. Publication bias was intuitively determined by funnel plot, and sensitivity analysis was conducted by removing literatures one by one for risk assessment.

[RESULTS] After reading the title, abstract, and full text, a total of 237 patients were included in 7 articles. Scar width was only studied in 6 literatures, and the heterogeneity test of the included studies (χ2 = 148.95, P < .001, I2 = 98%) showed significant heterogeneity among the studies. Therefore, the random effects model was used to merge the data. Combined effect value WMD =-2.85 [95% CI :(-6.51, 0.81), P < .001], the difference between the two groups was statistically significant. The combined OR of the random-effects model was 8.52 [95%CI: (7.96, 9.08), P < .001], and the difference between the two groups was statistically significant. Among them, the heterogeneity test (χ2 = 2.69, P = .44, I² = 0%) was carried out in two studies, indicating good homogeneity among the studies, so the combined WMD was 0.68 [95%CI: (0.38, 0.99), P < .001] by using the fixed-effect model. The median VAS was described in the other two literatures, and the mean scores in the experimental group were 8.9 and 8.25, respectively, while the mean scores in the control group were 7.2 and 6.28, respectively, indicating that local injection of botulinum A toxin at the early stage of wound healing can significantly improve scar quality. Sensitivity analysis suggested that the meta-analysis results were stable and reliable, and publication bias was not analyzed using funnel plots.

[CONCLUSION] Botulinum toxin has a positive effect on preventing hyperplastic scars in the maxillofacial and neck areas, and it can also help fade existing scars.