Preoperative Botulinum Toxin Injection Does Not Improve Hair Transplantation Outcomes: A Split-scalp Randomized Controlled Trial

Botulinum toxin (BoNT), derived from Clostridium botulinum, is widely recognized for its cosmetic applications and therapeutic efficacy in various neurological and dermatological disorders. In recent years, its potential role in treating hair related disorders has garnered increasing attention, including androgenetic alopecia (AGA) alopecia areata (AA), telogen effluvium (TE), and trichodynia-associated alopecia. Our own prior research corroborates these findings, indicating that for AGA patients with vertex hair loss, both intradermal injection within the alopecic area and intramuscular injection around the head effectively increase hair diameter, with the latter showing greater efficacy in improving hair density.
For AGA patients with male pattern (male pattern hair loss, MPHL) and patient with congenital high hairline (CHHL), hair transplantation constitutes a commonly employed treatment modality. While significant technical advancements have been made in transplantation techniques, persistent challenges include graft survival and preservation. Ischemia during the immediate post-implantation period is a primary contributor to transplantation failure. BoTN can improve the scalp microenvironment by enhancing local oxygenation and blood flow through vasodilation and reduced vascular pressure. Given the proposed mechanism of BoNT, we hypothesize that perioperative BoNT administration may offer a novel approach to enhance hair transplantation outcomes by mitigating ischemia-induced graft failure. To rigorously evaluate this hypothesis, we designed and registered the present randomized split-scalp controlled trial investigating the impact of preoperative BoNT on hair transplantation outcomes.