INTRODUCTION

Facial wounds, particularly the ones lying across the Lines of Langer, show poor healing with a tendency to scar. Several methods have been attempted to overcome this problem, including irradiation, ultrasound, corticosteroid injections, and silicone applications.[1] As these methods of treatment do not have optimum action on the pathology involved in the formation of scars, that is, combating the opposite pull of the muscle on immature collagen, acceptable results are not obtained. Extensive, hypertrophic, or atrophic scars with sharp borders are undesirable and unappealing. On occasions, a scar requires further management for a better aesthetic outcome with revisions and excisions. Very often, the scar may be oriented against the relaxed skin tension lines. To combat this, techniques such as Z or W plasty have been employed to orient the resulting scar in the desired direction. In addition to causing further scarring, very often, these have not been satisfactorily operative. Hence, in such instances, the BTA can be successfully utilized to eliminate the counteracting muscular forces around the scar. The BTA stimulates a temporary paralysis in the facial muscles, exerting the antagonizing forces against the healing of the wound, allowing it an adequate time frame for rest and collagen maturation and, in turn, optimal healing with a possible reduced chance of undesirable scarring. The BTA has been observed to have a negating influence on the transformation of fibroblast by transforming growth factor-β1 (TGF-β1). This is governed by an anti-heparin sulfate (anti-HS) effect due to the regulation of the phosphatase and tensin homolog (PTEN) methylation and phosphorylation of the responsible pathways.[2] Prevention of hypertrophic scars, better wound healing, and improvement of existing scars and wounds are known to be the benefits of BTA-induced “chemo-immobilization,” which is commonly known as BTA-induced paralysis.[3]

MATERIALS AND METHODS

Thirty patients with atrophic and hypertrophic scars, attending the dermatology outpatient department in Victoria hospital, BMCRI between April and October 2016, were included in the study. Patients having keloid scarring or keloidal tendency; pregnant and lactating patients; patients with a history of bleeding disorder or on anticoagulant therapy, oral steroid therapy; and patients with active skin infection such as warts, herpes, and bacterial infection were excluded from the study. Ethical clearance was obtained for the study.

Patients who were operated for the revision of scars were divided into two groups, comprising 15 participants each. In the first group, post-procedure, the area of maximum muscle activity, which was against resting skin tension lines (RSTL), was injected with 4–5 units of BTA at every 1-centimeter area radius [Figure 1]. The second group of patients were not injected with BTA post-procedure [Figure 2]. The patients were followed up for three months. The results were recorded, tabulated, and statistically analyzed.

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Figure 1 With botulinum toxin-A injection

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Figure 2 Without botulinum toxin-A injection

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RESULTS

The most common reason for scars was trauma (58%), followed by post-surgical scars (42%). The MSS was used to assess the scars. Student t-test and Levene’s test were used for data analysis.

In the first group, nine cases had an MSS of 17, two cases had an MSS of 16, and four cases had an MSS of 15. After surgical correction and BTA injection, the MSS reduced from 17 to 7 in seven cases, to 8 in two cases, and from 16 to 7 in two cases. The MSS reduced from 15 to 7 in three cases and to 8 in one case [Table 1].

In the second group, scars in eight cases had an MSS of 17, one had an MSS of 16, and six had an MSS of 15. After surgical correction, MSS reduced from 17 to 11 in five cases, to 10 in three cases, and from 16 to 10 in one case; similarly, MSS reduced from 15 to 11 in cases and to 10 in three cases. Results were statistically significant at a 95% confidence interval (P < 0.01).

DISCUSSION

Key functions of the perioral musculature include facial expression; action of the oral sphincter, including articulation. For wounds around the operated areas, it is recognized that the tensile strength and the exerting forces during the healing process provide a rather unfavorable effect on the scars, which, many times, results in a poor and unpleasant nature in healed scars. These actions are reduced with the BTA injection. With the resulting immobilization of perioral wounds, temporary functional insufficiencies may be expected.

In a meta-analysis conducted by Guo et al., it was found that the patients given the BTA injection fared better than the placebo or blank control group in terms of enhancing scar quality and better healing of wounds. The undesirable effects for BTA treatment in these patients were only negligible adverse events.[3]

Numerous studies advocate that superior wound healing results from BTA-induced immobilization of facial wounds.[456789] Chemoimmobilization of cutaneous wounds is employed to reduce active strain on the healing tissues. A study conducted by Gassner et al. showed there was an enhanced quality of wounds in terms of cosmetic appearance in postoperative scars of rabbit ears after the BTA injection. This possibility resulted from the muscle paralysis and decreased muscle tension during healing.[4] The BTA injection has been utilized for more than 20 years in the treatment of many varied cosmetic and non-cosmetic conditions such as strabismus, nystagmus, achalasia, anal fissure; dystonias, including cerebral palsy, torticollis, dysphonia, blepharospasm, hemifacial spasm, and hyperhidrosis. It has been famously employed in the treatment of hyperkinetic lines.

The BTA injection is used as an adjunctive treatment. It has also been used in conjunction with other treatment modalities such as intense pulsed light, resurfacing, and fillers, constituting a comprehensive “rejuvenation” plan.[10] To avoid unwanted action on the deeper muscle, it would be better to inject a low dose (5 units would be sufficient in most cases) of the BTA at the time of the procedure or if desired at suture removal. Care should be especially taken in cases on the cheek and not involving the midline, if not as much on other areas of the body.

The BTA is also known to cause inhibition of the fibroblasts, therefore providing us with another significant function utilized for the therapy of challenging scars. This is in addition to the reduced expression of connective tissue growth factor, which functions as a downstream regulator of TGF-β1,[11] in turn reducing the levels of TGF-β1 in fibroblasts.[12] The BTA also functions by reducing the infiltration of inflammatory cells during wound healing, and it also leads to an extension of its length.[13] A study conducted by Wang et al. explained that the usage of BTA in scars inhibited collagen production and the fibroblasts’ cell cycle in vivo.[14]

In our study, we establish a significant reduction in the severity of scars measured by the MSS after the BTA injection around the suture line post-procedure, as opposed to a reduced betterment of scar tissue in cases where the BTA was not used.

CONCLUSION

This study demonstrates the positive effect of BTA as an adjunctive treatment for the betterment of the surgical correction of atrophic and hypertrophic scars.