A personalized treatment approach of frontalis muscle with botulinum toxin A (Bont-A) related to functional anatomy: case studies.

Background

The forehead is one of the most frequent sites of botulinum toxin (Bont-A) application. To date, few data are available about the anatomy of the frontalis muscle. Its anatomy is highly heterogeneous in Caucasian people. Consequently, personalized treatments with botulinum toxin-A (Bont-A) are needed to obtain good esthetic results and to reduce side effects. Recently, a study on cadavers found four anatomical shapes of the frontalis muscle, corresponding to four horizontal wrinkle patterns in live patients.

Objective

To perform a personalized, reproducible, and safer treatment with Bont-A of the forehead, by classifying patients according to four specific anatomical shapes of the frontalis muscle related to skin wrinkle patterns during contraction.

Methods

We treated four patients classified according to the four anatomic types (I, II, III, and IV). The patients' forehead was divided into 21 areas and matched with 4 horizontal wrinkle patterns. Detecting different activities of the muscle in the different areas of the forehead, treatment injections were performed with a different dose, dilution, and at different anatomical layers (intramuscular or intradermal) per point.

Conclusions

We confirmed four different wrinkle patterns after forehead contraction according to the anatomical shape of the frontalis muscle. This allows us to perform a tailored treatment with Bont-A. Nevertheless, some patients with atypical patterns still need "ad hoc" treatment.