Botulinum Toxin and Burn Induces Contracture

Article information

Arch Plast Surg. 2016;43(6):609-611
Publication date (electronic) : 2016 November 18
doi : https://doi.org/10.5999/aps.2016.43.6.609
1Department of Plastic Surgery, Isfahan University of Medical Sciences, Isfahan, Iran.
2Department of Anesthesiology, Isfahan University of Medical Sciences, Isfahan, Iran.
3Department of Community Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
Correspondence: Narges Motamedi. Department of Community Medicine, Isfahan University of Medical Sciences, Hezarzerib St, Isfahan 8174673461, Iran. Tel: +98-91-3225-2202, Fax: +98-31-448-1192, motamedi.narges@yahoo.com
Received 2015 January 26; Revised 2016 February 17; Accepted 2016 March 16.

Scar formation is one of the physiological processes of wound healing in the deepest part of the damaged dermis [1]. Hypertrophic scars and keloids are formed as the muscles pull the edges of a wound while the collagen fibers of the skin are still immature [2]. Temporarily paralyzing the muscles around the wound with botulinum toxin is one of the newer methods used during the process of reconstructive surgery [2]. Botulinum toxin directly inhibits fibroblast-to-myofibroblast differentiation in vitro, and it is indicated for its potential use in the treatment of wounds after trauma, burn, or surgery [3]. However, based on the available information, it is difficult to predict the therapeutic response of scars to botulinum, and more studies are needed before this method can become a standard therapy. We studied the effectiveness of a botulinum toxin injection in the recovery rate of contractures, which was burn induced and did not recovery acceptably by the surgical reconstruction of scars.

This was a randomized, controlled clinical trial. Patients aged 2 to 50 years with a chronic burn scar with contracture in certain areas of the body include joints, palms , eyelids, lip and cheek, were enrolled in the study. The burn must have occurred at least three months before the intervention and it must have produced a red scar (an immature scar).

Exclusion criteria were the previous treatment of spasticity, known sensitivity to botulinum toxin, isease that affects muscles, or use of aminoglycoside antibiotics such as spectinomycin within a period 30 days before or during the study.

The participants were divided into two groups. One group received an injection of botulinum toxin and the second group was followed without any intervention.

In the adults we injected botulinum toxin as 100 Units of Botox into the center, around the periphery, and at the two ends of the lesion. The method of injection was meso injection, in which botulinum toxin was injected subdermally, intradermally and into the scar, diffusely.

In children under 15 years old, the dose was 50 Units of Botox and in the children under five, 25 units.

In palms, upper eyelid and the small joints such as fingers, the maximum dose was 10 units.

In the lower eyelid, lower lip, and cheek, 10–15, 15–20, and 10 units were injected, respectively.

All patients were followed for six months with the same schedule.

In the major joints, we used a plastic manual goniometer (Phoenix Healthcare Products, Nottingham, UK) to a precision of 1°. Range of motion was defined between 0° and 100°.

For eyelid contracture, scoring was defined as follows [4]: complete closing, 4; pupils not visible, 3; pupils visible, 2; and complete opening, 1.

Of the 50 subjects, eight were lost during the follow-up. The baseline characteristics of the lost subjects were same in the intervention and control groups.

We analyzed the data of the 42 remaining patients. Among them, 51% were male and 49% female.

The total mean±standard deviation of age was 20.5±10.8.

The sex and age distribution was similar in both groups (P>0.05).

The range of motion of contracted parts of the body before and after intervention is shown in Table 1. Before injection, the range of motion in the intervention group was 58±17.6, and in the control was 73.9±32.9 (P>0.05). After injection, it changed to 89.8±21.5 and 81±43.5, respectively. This means that the improvement was 43% greater in the botulinum toxin group. Although the intervention group had more contracture than the control group, the difference was not statistically significant. Although the range of motion improved in both groups, the change in the range of motion was significantly greater in the intervention group (30.9° vs. 7.1°, respectively).

Active extension in botulinum toxin and placebo groups (before, after, and change in degrees)

The severity of eyelid contracture in the control group did not change, while in the intervention group, it improved but not significantly (Table 1) (Fig. 1).

Fig. 1

Eyelid scar changes in a case of botulinum toxin injection. (A) First injection, 3 months after burn. (B) 3 months after injection, 6 months after burn.

Fig. 2 shows scar changes before and 3 months and 5 months after injection of botulinum toxin.

Fig. 2

Scar changes in a case of botulinum toxin injection. (A) First injection, 3 months after burn. (B) 3 months after injection, 6 months after burn. (C) 5 months after injection, 8 months after burn.

Generally, botulinum toxin injections relaxed the scar tissue, then established blood flow; this mechanism enabled the process of remodeling [5].

This study showed that for the endpoint, there was no statistically significant difference between treatment groups. This seems to be due to the small sample size. Although burn-induced contracture decreased during the healing period even without any intervention, the study detected a change of 30.9° versus 7°, which was considered to be of clinical relevance and to represent a clinically meaningful improvement in functional gain.

Notes

No potential conflict of interest relevant to this article was reported.

References

1. Gauglitz GG. Therapeutic strategies for the improvement of scars. Prime 2012;2:16–27.
2. Wilson AM. Use of botulinum toxin type A to prevent widening of facial scars. Plast Reconstr Surg 2006;117:1758–1766. 16651948.
3. Jeong HS, Lee BH, Sung HM, et al. Effect of botulinum toxin type a on differentiation of fibroblasts derived from scar tissue. Plast Reconstr Surg 2015;136:171e–178e.
4. Malhotra R, Sheikh I, Dheansa B. The management of eyelid burns. Surv Ophthalmol 2009;54:356–371. 19422964.
5. Welch MJ, Purkiss JR, Foster KA. Sensitivity of embryonic rat dorsal root ganglia neurons to Clostridium botulinum neurotoxins. Toxicon 2000;38:245–258. 10665805.

Article information Continued

Fig. 1

Eyelid scar changes in a case of botulinum toxin injection. (A) First injection, 3 months after burn. (B) 3 months after injection, 6 months after burn.

Fig. 2

Scar changes in a case of botulinum toxin injection. (A) First injection, 3 months after burn. (B) 3 months after injection, 6 months after burn. (C) 5 months after injection, 8 months after burn.

Table 1

Active extension in botulinum toxin and placebo groups (before, after, and change in degrees)

Groups Mean Standard deviation 95% Confidence interval P-value
Lower Upper
Range of motion
 Before NSa)
  Botox 58.9 17.6 51.7 66.1
  Control 73.9 32.7 51.7 88.8
 After NS
  Botox 89.8 21.5 80.5 98.4
  Control 81 43.5 60.1 99
Change Sb)
 Botox 30.9 19.5 22 37.8
 Control 7.1 47 −13 28.8
Eyelid contracture change NS
 Botox 33.3 12.8 25.1 50.8
 Control 8.3 12.9 0 25.9

a)Non significant; b)Significant at level 0.05.