Intradermal injection of botulinum toxin type A (Botox) immediately following wound closure improved the appearance of facial surgical scars compared with control scars in a small, randomized, double-blind trial from the People’s Republic of China.
At 6 months’ follow-up, the half of each facial scar treated with the injections following wound closure was narrower and flatter than the half left untreated, Li Hu, MD, PhD, and colleagues from the Shanghai Jiao Tong University School of Medicine Shanghai, reported in Plastic and Reconstructive Surgery.
The mean Vancouver Scar Scale score, used to characterize hypertrophic scars, was also lower for the half of the scar that was treated with the toxin, at 4.68 compared with 5.24 for the half that was not treated, although this difference was not statistically significant (P=0.146), the investigators added.
“Too many reports have focused on the treatment rather than the prevention of untoward surgical scars. However, early management of surgical scars is more likely to yield a better cosmetic appearance and require fewer treatments. This study demonstrates that early postsurgical botulinum toxin injections can produce better, narrower, and flatter facial surgical scars [than scars that remain untreated].”
For the study, 16 patients were randomized to receive botulinum toxin type A injections to half of their facial scar and the other half of the scar was treated with 0.9% normal saline.
“Immediately after skin closure, the encoded vial contents (0.2 mL containing 10 U for each 1-cm scar) were injected at a distance of 5 mm on either side of the wound,” the team wrote. The mean amount of botulinum toxin injected per scar was 33.7 U (range, 15 to 80 U). The mean age of the subjects was 12 (range, 6 to 49), while the mean length of the scar was 6.74 cm (range, 3 to 16 cm). The original diagnoses included congenital melanocytic nevi, port-wine stains, arteriovenous malformations, and disfiguring scars. Fourteen of the 16 patients completed the study.
In a subset analysis, the difference in the Vancouver Scar Scale height score at 6 months was significantly lower, at 0.47 for the treated part of the scar compared with 0.76 for the half that was not treated (P=0.009). At the same time point, the treated portion of the scar was also significantly narrower at 0.32, compared with 0.43 (P=0.001) for the untreated segment of the scar. The mean visual analogue scale (VAS) score was also higher at 5.76 for the treated part of the scar, compared with 4.97 for the control side — a difference between the two sides that was again significant (P=0.046).
In contrast, no significant differences were seen in the subdomains of pigmentation at 1.63 for the treated side versus 1.58 for the control side (P=0.391) or in vascularity, at 1.24 for the treated side versus 1.32 for the control side (P=0.263). No adverse events were noted. Tension at the edges of a wound significantly contributes to unsightly scars, the researchers explained.
“Temporary muscular paralysis induced by botulinum toxin type A could decrease movement and stress around a healing wound. This relief of tension may help prevent facial scar widening, hypertrophy, and hyperpigmentation.”
The authors also noted that botulinum toxin may have a direct inhibitory effect on fibroblasts and transforming growth factor-β1 expression, both key to the development of hypertrophic scars. A previously published study similarly found that early injections of the same botulinum toxin improved the appearance of facial scars — again by inducing temporary muscle paralysis and decreasing tension on wound edges.
Asked for her opinion, Tina Alster, MD, director of the Washington Institute of Dermatologic Laser Surgery in Washington, D.C., who was not involved with the study, pointed out that one of the limitations was the small sample size. She also noted that in general, scars on the face and neck tend to heal fairly well, as they are not under a lot of tension, which can contribute to unsightly scars.
However, she said she agreed in principle that starting early to try and minimize scars is a good idea: “I do a lot of laser scar revision and even using lasers to reverse red or hypertrophic keloid scars, we found that the earlier you start using the laser, the less severe the scar, and the earlier the scar looks better.”
In addition, Alster said, for many practitioners, incorporating the use of botulinum toxin into the practice of scar management is likely to be more readily available than the use of lasers, although in her own practice, she has found it actually to be less expensive and even less invasive to use a laser for scar revision than to inject botulinum toxin around a wound.
“I think it’s an important study if only because it asks the question, will the use of Botox or any of the other neuromodulators reduce scar formation by directly reducing the mechanical forces across a wound bed, and that answer is likely yes.”
“So in general this is a ‘thumbs up’ study, but with the caveat that larger studies of more significant scars are still warranted.”
The study authors, as well as Alster, reported having no financial conflicts of interest.
F. Perry Wilson, MD, MSCE Assistant Professor, Section of Nephrology, Yale School of Medicine and Dorothy Caputo, MA, BSN, RN, Nurse Planner