Glabellar contraction patterns: a tool to optimize botulinum toxin treatment.

BACKGROUND: Botulinum toxin is a well-established treatment for dynamic glabellar lines. A previous study evaluated the existence of glabellar contraction "patterns," according to the predominance of eyebrow approximation, depression, or elevation movements, namely "U," "V," "convergent arrows," "omega," and "inverted omega." OBJECTIVES: To confirm contraction patterns in the adult population for a better treatment approach and to verify whether changes occur after repeated treatment. METHODS: Pairs of photographs-at rest and under contraction-from two groups were retrospectively analyzed: 334 adult volunteers with a predominance of specific movements, being verified and 36 previously treated individuals when they returned for re-injections. RESULTS: The five glabellar contraction patterns were confirmed. Each individual's initial pattern reappeared upon waning of the toxin effect. CONCLUSION: Interpersonal differences in facial animation are observed. Classifying glabellar wrinkles allows accurate treatment with botulinum toxin, injecting the most commonly recruited muscles with higher doses or into more sites. Muscles not so recruited are spared or injected with lower doses for more-effective and -natural results. Although botulinum toxin blockade causes recruitment of adjacent muscles, the initial muscle contraction pattern is resumed when the effect wanes.