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) is a neurotoxin widely used for facial aesthetics. It 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 (photos), but a negative impact in dynamic recordings (videos). OBJECTIVE Comparison of emotional expression recorded in photos and videos before and after treatment with BTX. METHODS Twenty healthy women (mean age: 45) received a dose of 19 mouse units (XEOMIN®, Merz, Frankfurt am Main, Germany) into the procerus, occipitofrontalis and orbicularis oculi muscles. Photos and videos of the participant's faces with neutral and happy expressions were recorded before treatment and two weeks later. Recordings were rated by naive raters blind to the conditions and in balanced order. RESULTS Videos compared to photos were generally rated as more pleasant, arousing, attractive and genuine (all ps>.001). This was especially the case for videos with neutral expression (p=.003). Independent of presentation mode and facial expression, women were rated as more attractive after BTX treatment (p=.03). CONCLUSION 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 in order to evaluate the effects of treatment with BTX. BTX seems to improve perceived attractiveness, though the cause of this effect remains unclear.