SKIN 
 

December 2018     Volume 2 Supplemental Issue  
 

Copyright 2018 The National Society for Cutaneous Medicine 99 

RISING DERM STARS 
 

 
Prophylactic botulinum toxin in post-excisional scars: a randomized, 
doubleblinded, controlled clinical trial 
 
Danielle P Dubin BA, Richard L Torbeck MD, Daniel M Bernstein MD, Matthew J Lin MD, Hooman 
Khorasani MD 
 

 
 
Background: Excision of non-melanoma 
skin cancer on the face is usually curative, 
but the resultant scar in this cosmetically 
sensitive area may cause significant distress. 
Excessive wound tension may impair the 
healing process and lead to unsightly scars1; 
therefore, one of the key principles in 
cutaneous surgery is to minimize wound 
tension. Botulinum toxin is utilized as a 
treatment for facial rhytids due to its ability to 
induce a chemical paralysis of the 
musculature2. It has been hypothesized that 
it may also be used to minimize facial scars 
by paralyzing facial muscles, thereby leading 
to reduced wound tension. 
 
Objective: To assess post-operative scar 
outcomes after administration of botulinum 
toxin at the time of excisional skin cancer 
surgery. 
 
Methods: In this single center, single 
surgeon, double-blinded, prospective, 
randomized clinical trial, 25 Caucasian 
patients ≥ 18 years of age were randomized 
to receive either botulinum toxin injections or 
placebo injections of normal saline 
immediately following closure of skin cancer 
defects from Mohs Micrographic Surgery on 
the forehead. All defects underwent layered 
closure by a single dermatologic surgeon 
with thirteen years of surgical experience. 
Botulinum toxin (50 units) or saline (1 mL) 
were then injected in a standardized pattern 

on the forehead (Figure 1). Wounds were 
dressed in a standardized manner with 
Mastitol®, Steri-Strips®, Telfa®, gauze, 
Hypafix® and cutaneous sutures were 
removed 7 days after surgery. The primary 
outcome was a blinded assessment of the 
scar six months after surgery with the 
modified Manchester Scar Scale (mMSS) 
and Visual Analog Scale (VAS). The study 
arms were compared using the Mann-
Whitney U test. Two-tailed tests with a 
significance level of 5% were used. 
 
Results: The placebo and botulinum toxin 
groups were similar in terms of age (mean of 
57 and 59), gender (female:male ratio 5:6 
and 5:9), smoking history (2 and 3 patients, 
respectively), autoimmune disorders (1 
each), and scar location. There was no 
significant difference in mMSS scores 
between the study arms (median 10.00 and 
10.15, p = 0.79). Similarly, there was no 
significant difference in the VAS scores 
(median values 3 and 3, p = 0.87). Analysis 
of subgroups stratified by age, gender, 
closure type, scar orientation, and sub-
locations also failed to demonstrate a 
significant difference. 
 
Conclusion: When administered at the time 
of wound closure, botulinum toxin does not 
significantly improve post-operative facial 
scar outcomes. Further studies are needed to 
determine the efficacy of prophylactic 



SKIN 
 

December 2018     Volume 2 Supplemental Issue  
 

Copyright 2018 The National Society for Cutaneous Medicine 100 

administration of botulinum toxin prior to 
wound closure, which may allow for 
maximum chemical paralysis of the facial 
musculature. 
Figure 1: Standardized injection pattern for both 
study arms. 

 
 
 
Figure 2: Box plot comparing VAS and mMSS for 
the placebo versus botulinum toxin study arms. 

 
 

References: 
References: 
1. Meyer, M, and DA McGrouther. “A Study 
Relating Wound Tension to Scar 
Morphology in the Pre-Sternal Scar Using 
Langers Technique.” British Journal of 
Plastic Surgery, vol. 44, no. 4, May 1991, pp. 
291–294., doi:10.1016/0007- 
1226(91)90074-t. 
2. Carruthers, Jean D.A., and J. Alastair 
Carruthers. “Treatment of Glabellar Frown 
Lines with C. Botulinum-A Exotoxin.” The 
Journal of Dermatologic Surgery and 

Oncology, vol. 18, no. 1, 1992, pp. 17–21., 
doi:10.1111/j.1524- 
4725.1992.tb03295.x