Plastic Surgery Research Council
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PSRC 60th Annual Meeting

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Effect of Glabellar Paralysis by Botulinum Toxin on Ability to Communicate Emotion
Jason T. Laurita, MB1, Mitchell A. Stotland, MD1, Mitchell Horn-Wyffels, MD2, Belinda B. Ray, MA1.
1Geisel School of Medicine at Dartmouth, Hanover, NH, USA, 2University of Minnesota, Minneapolis, MN, USA.

PURPOSE:
Two important, potential behavioral effects of botulinum toxin (BTx) are debated: (1) Does paralysis of glabellar musculature alter mood or emotion through the mechanism of the facial feedback hypothesis? And, (2), does BTx significantly alter one’s ability to facially express emotion? Recent neuroscientific studies have demonstrated that corrugator muscle paralysis can, in fact, alter the perception of emotional stimuli and downgrade amygdala response to anger. Regarding the second question, however, both the lay-press and prospective patients commonly disparage the presumed “expression-erasing” effects of facial BTx treatments despite a lack of any formal evidence. In this study the influence of glabellar BTx on the perceived legibility and intensity of the 6 cardinal expressions of emotion (happy, sad, afraid, surprised, angry, disgusted) is rigorously quantified for the first time.
METHODS:
Phase 1: 52 “expressor” females (age 35-60) were induced to spontaneously express the 6 cardinal emotions both before and 1 month after glabellar injections of BTx. A hidden video camera recorded subjects as they viewed provocative movie clips previously validated to stimulate the different facial expressions of emotion.
Phase II: 21 “perceivers” evaluated the video of all 52 “expressors” viewing the anger-provoking movie clips both pre-BTx treatment (perceivers blinded to treatment or study objective). Ratings for emotional intensity (1-7 scale) were tabulated. The 10 most intense “expressors” were selected out for use in Phase III.
Phase III: 31 new “perceivers” viewed movie clips of the 10 most intense “expressors” pre- and post-BTx (120 clips viewed by each "perceiver", displayed in random order). Each clip was rated for legibility (% accuracy selecting 1 of 6 cardinal emotions) and for intensity (1-7 scale).
RESULTS:
1) Legibility of facial expression:
In those expressing emotion, glabellar BTx injection does not cause a significant change in perceivers’ ability to discern the 6 cardinal emotions.
2) Intensity of facial expression:
Glabellar BTx injection results in a perceived significant reduction (3.77/7 vs 1.89/7; p<0.0001) in the intensity of the anger expression, but has an insignificant effect on the other 5 cardinal emotions.
CONCLUSION:
BTx injections in the glabellar region significantly reduce the intensity of anger expression (p<.0001). However, perceivers maintain an ability to discern the facial expression of all 6 cardinal emotions.






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