Appropriate Timing of Early Postoperative Botulinum Toxin Type A Injection for Thyroidectomy Scar Management: A Split-Scar Study

Background: Botulinum toxin type A (BTxA) injection is effective for surgical scar prevention. Although some studies have aimed to confirm the efficacy of BTxA injection at different time points, none has been conducted to determine the most appropriate timing of injection for scar management. The authors predicted that the injection of BTxA at different times during the wound healing process would cause differing scar quality improvement and clarify unknown molecular mechanisms. Methods: The study included adults who underwent thyroidectomy. All patients received paralesional BTxA injections on the day of the surgery on either the right or left side of the operative site. The same dose was injected on the noninjected side by means of the same method after 2 weeks. At 2, 4, 12, and 24 weeks postoperatively, the modified Stony Brook Scar Evaluation Scale, visual analogue scale, and erythema index were used for objective, subjective, and quantitative evaluations of the scar. At week 24 postoperatively, a quantitative scar assessment was performed with respect to the erythema index, skin elasticity, melanin index, and friction. Results: On objective evaluation of the scar and patient satisfaction at 24 weeks postoperatively, the operation-day injection side showed better outcomes than the 2-week-postoperative injection side. These differences were significant from postoperative week 4. In the final quantitative scar assessment at postoperative week 24, significant improvements were observed in the erythema index and skin elasticity. Conclusion: These results suggest that immediate postoperative BTxA injection is more effective for thyroidectomy scar management in terms of erythema, skin elasticity, and patient satisfaction.