The Quantitative Assessment of Wrinkle Depth: Turning the Microscope on Botulinum Toxin Type A

Three-Dimensional Evaluation of Static and Dynamic Effects of Botulinum Toxin A on Glabellar Frown Lines

BACKGROUND

The use of injectable solutions for aesthetic purposes has increased tremendously, but lacks objective support. We aimed at assessing static and dynamic effects of botulinum toxin A (BoNTA) on glabellar lines by use of an objective three-dimensional methodology.

METHODS

We prospectively collected three-dimensional stereographic photographs of two different facial expressions (pretreatment, 30 and 90 days posttreatment) in 21 patients, receiving a total of 20 units of BoNTA in both corrugator supercilii muscles. The primary endpoint was the three-dimensional static and dynamic surface irregularity, and secondary endpoints were the glabellar line scale and overall patient satisfaction. Blinded retrospective data analysis and statistical evaluation were performed with p < 0.05 considered statistically significant.

RESULTS

Static glabellar lines (neutral facial expression) were significantly reduced by - 17% and - 24% on day 30 and 90 posttreatment, respectively (vs. pretreatment; both p < 0.0001). Dynamic glabellar frown lines (firmest possible bilateral eye closure) demonstrated a reduction of surface irregularity by - 26% and - 21% on day 30 and 90 posttreatment, respectively (vs. pretreatment; both p < 0.0001). The subjective dynamic glabellar line scale documented a statistically significant improvement on day 30 posttreatment (mean ± SD: 1.5 ± 0.8; p < 0.05) versus pretreatment (2.8 ± 1.0). Polled patients confirmed a subjective wrinkle improvement 90 days posttreatment.

CONCLUSION

The presented setup detected even subtle changes of BoNTA treatment for facial wrinkling and is a promising asset for scientific evaluations of clinical studies analyzing the outcome and duration of efficacy of injectable solutions on the face.

LEVEL OF EVIDENCE IV

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Aesthetic uses of the botulinum toxin

The cosmetic use of botulinum toxin (BoNT) is the most common cosmetic procedure performed in the world today. Common adverse events seen in the aesthetic use of the BoNT include swelling, localized bruising, headaches, injection site discomfort, excessive muscle weakness, and unintended paresis of adjacent muscles. BoNT has a wide array of cosmetic uses, including treatment of glabellar lines, chemical browlift, forehead wrinkles, periorbital, and perioral lines. The future formulations and applications of BoNT type A will be plentiful, and are exciting to consider.

Botulinum neurotoxin A: a review

Despite its ubiquity in cosmetic circles and broad general awareness, a literature search of botulinum neurotoxin in JPRAS and BJPS yielded a mere 4 articles germane to cosmesis. A pair each detailing its application in masseteric hypertrophy(1,2) and the use of cryoanalgesia.(3,4) Given that botulinum neurotoxin A is the most commonly used cosmetic treatment, with American figures being most accurate,(5) a review of the background, development and scientific evidence would be perhaps useful, if not overdue, as Plastic Surgeons increasingly incorporate non-surgical interventions into their practices as part of a comprehensive facial rejuvenation strategy.

Development and validation of a new clinically-meaningful rating scale for measuring lateral canthal line severity

BACKGROUND

Several scales have been employed for evaluating the effects of cosmetic treatments in the periorbital area. The Food and Drug Administration (FDA) has recently issued new recommendations specifying a rigorous process to validate new aesthetic scales.

OBJECTIVES

The authors describe and validate a new clinical rating scale: the Investigator's Global Assessment of Lateral Canthal Line (IGA-LCL) severity scale.

METHODS

The new FDA recommendations were utilized to validate the new scale. The first step was concept elicitation (based on direct input from clinicians, patients, and literature) and evaluation of content validity (appropriateness of concepts). The resulting five-point scale provided detailed descriptions of the lateral canthal lines (LCL), including quantitative assessment of LCL length and depth. Performance parameters, including intra- and interrater reproducibility and construct validity, were then evaluated in clinical studies. Finally, the scale's threshold for clinically-meaningful benefit and the ability of the scale to detect change were confirmed in two Phase 2b clinical studies involving a total of 270 subjects.

RESULTS

Content validity was established and the IGA-LCL scale showed excellent interrater reliability (weighted Kappa = 0.89) and interrater reliability (weighted Kappa = 0.77; Kendall's coefficient of concordance = 0.89). In clinical trials, the scale was sensitive enough to detect clinically-meaningful one- and two-point changes in LCL severity following treatment with topical botulinum toxin type A (BoNT-A). The authors observed statistically-significant correlations between the physician-rated IGA-LCL results and patient-reported outcomes.

CONCLUSIONS

The IGA-LCL scale was shown to be reliable, appropriate, and clinically meaningful for measuring LCL severity.

Botulinum toxin type a inhibits connective tissue growth factor expression in fibroblasts derived from hypertrophic scar

BACKGROUND

Botulinum toxin type A (BTXA) can inhibit the growth of hypertrophic scars, but the molecular mechanism for this action is unknown. In addition to reducing the tension around the wound by stimulating temporary denervation, a growing body of evidence suggests that BTXA is involved in regulating the cell cycle and decreasing transforming growth factor-β1 (TGF-β1) expression in the fibroblasts of hypertrophic scars. Connective tissue growth factor (CTGF) is a downstream regulator of TGF-β1 function and an independent mediator of scarring and fibrosis. The effects of BTXA on CTGF in hypertrophic scar still are unknown. This study aimed to explore the effect of BTXA on CTGF in fibroblasts derived from hypertrophic scar and to elucidate its actual mechanism further.

METHODS

Fibroblasts isolated from tissue specimens of hypertrophic scar were treated with BTXA. The difference in proliferation between treated and nontreated fibroblasts was analyzed by flow cytometry. Proteins of CTGF were checked using Western blot in fibroblasts with and without BTXA.

RESULTS

The proliferation of the fibroblasts treated with BTXA was slower than that of the fibroblasts that had no BTXA treatment (p < 0.01), which showed that BTXA effectively inhibited the growth of fibroblasts. Compared with fibroblasts that received no BTXA treatment, BTXA at 1 U/10(6) cells decreased the expression of CTGF by 49.2% ± 12.5% (p < 0.01), and BTXA at 2.5 U/10(6) cells decreased the expression of CTGF by 56.9% (p < 0.01).

CONCLUSION

These results suggest that BTXA effectively inhibited the growth of fibroblasts derived from hypertrophic scar and in turn caused a decrease in CTGF protein, providing theoretical support for the application of BTXA to control hypertrophic scarring.