Ratings of Emotional Expressions in Static and Dynamic Facial Recordings Before and After Upper Face Botulinum Injections-An Observational Prospective Study.

Background: Botulinum toxin A (BTX), a neurotoxin widely used for facial aesthetics, causes dose-dependent muscle paralysis. It was hypothesized that treatment of mimic muscles with BTX might have a positive impact on emotional expression in static images (photographs), but a negative impact in dynamic recordings (videos).

Objectives: The aim of this study was to compare of emotional expression recorded in photographs and videos before and after treatment with BTX.

Methods: Twenty healthy women (mean age, 45 years) received a dose of 19 mouse units of XEOMIN (Merz, Frankfurt am Main, Germany) into the procerus, occipitofrontalis, and orbicularis oculi muscles. Photographs and videos of the participants' faces with neutral and happy expressions were recorded before treatment and 2 weeks later. Recordings were rated by naive raters blind to the conditions and in balanced order.

Results: Videos were generally rated as more pleasant, arousing, attractive, and genuine than photographs (all Ps > 0.001). This was especially the case for videos with neutral expression (P = 0.003). Independent of presentation mode and facial expression, women were rated as more attractive after BTX treatment (P = 0.03).

Conclusions: In contrast to the hypothesis, the reduced mobility had no detectable negative impact on dynamic emotional expression, but videos received more positive ratings, particularly for neutral expressions. It is thus recommended to assess emotional expression with dynamic recordings to evaluate the effects of treatment with BTX. BTX seems to improve perceived attractiveness, although the cause of this effect remains unclear.