Botulinum Toxin A Plays an Important Role in the Placement of Implants Deep Within the Pectoralis Major Muscle for Mammaplasty: A Systematic Review and Meta-analysis.

[BACKGROUND] Breast prosthesis implants have been safely and efficiently used in the plastic surgery department. With the increasing demand for aesthetics, these silicon implants were not only used in breast augmentation surgery but also in breast reconstruction after mastectomy. Nevertheless, breast prosthesis implantation brings a lot of complications, such as: postoperative chronic pain, capsule contracture, prosthesis displacement and prosthesis rupture and infection in severe cases. From the year 1998, botulinum toxin A (BTX-A), a neurotoxin, has been reported to be effective for pain control, capsule contracture lessening, expander enlargement and so on. However, those articles included all kinds of study types: randomized, double-blinded controlled trial (RCT), nonrandomized trial, retrospective analysis and case series, besides the outcomes were varied. To clarify how BTX-A acts at the mammaplasty field, we made this systematic review and meta-analysis.

[PURPOSE] To review how BTX-A acts in the field of mammaplasty as well as discuss the relative mechanisms of BTX-A and the related research progress.

[METHODS] We searched Pubmed, Embase, Cochrane, Web of science, Clinical trials, Wanfang Database and VIP from inception until March 2018 for papers reporting the use of BTX-A in the breast surgery using implants deep within the pectoralis major muscle. System review, viewpoints and case reports were excluded.

[RESULTS] Ten articles met the criteria for inclusion including six prospective controlled (2 RCT; 4 other trails), three retrospective cohorts and one case series. These studies were all about patients using BTX-A during or after breast surgery with expanders or prostheses. A total of 682 patients were enrolled, 543 (79.61%) accepted BTX-A injection, 185 underwent mastectomies with immediate reconstruction, 13 with delayed reconstruction, 295 mastectomies with either immediate or delayed reconstruction and 189 with breast augmentation using silicone prostheses. The study time ranging from 4 months to 13 years, 15 patients (2.76%) received BTX-A injection more than two times, 9.2% received less than 75 U BTX-A, 34.3% 75-100 U, 0.18% 250 U, and in 56.4% the dosage was not stated. No complications associated with BTX-A were mentioned, almost all the studies reported efficacy for pain control. Other assessments included increased speed of expander enlargement and volume were mentioned in four papers, two articles analyzed the visual analogue scores, three suggested relief of capsular contracture, two reported lower narcotic use, three mentioned shorter hospital stays and one proved lowering the rate of unplanned expander. It seems all the studies demonstrate the valid usage of BTX-A, but the quality of this evidence still under the line.

[CONCLUSION] We could try to use BTX-A as a new method in the field of mammaplasty. There are so many advantages such as postoperative pain relief, reducing the hospital stay, and increasing operation success rate, but rigorous methodological evidence is still lacking. A lot of studies were retrospective, only two studies used the RCT method. Therefore, to obtain strong evidence to clarify the usage of BTX-A, more randomized double-blinded controlled trials will be required, meanwhile the mechanism study adds to the evidence.

[LEVEL OF EVIDENCE III] This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .