Seraina L. C. Müller, Chantal Zeier, Pablo Pfister, Nadia Menzi, Bita Tafrishi, Dirk J. Schaefer, Jan A. Plock, Tarek Ismail, Holger J. Klein
Facial palsy affects millions worldwide. Botulinum toxin Type A (BoNT-A) is an established treatment for non-flaccid facial palsy, yet objective evidence remains limited. This study evaluates the effects of BoNT-A using AI-based tools and patient-reported outcome measures (PROMs). In this prospective observational study, patients with non-flaccid facial palsy received individualized BoNT-A injections. Exclusion criteria included age < 18, hypersensitivity to BoNT-A, or lack of follow-up. Assessments were conducted before and 3 weeks after treatment, including facial symmetry (Emotrics®), emotion expression (FaceReader™), and PROMs (FaCE and FDI). Eleven patients (mean age 50.1 ± 18 years) were included. BoNT-A significantly improved dynamic facial symmetry: eyebrow raising (p = 0.032), smile angle (p = 0.005), and lower lip height (p = 0.042). Emotion analysis showed no significant changes. PROMs revealed improvements in social well-being (FDI, p = 0.004) and aesthetic satisfaction (FaCE, p = 0.035), while functional FDI scores remained unchanged (p = 0.406). BoNT-A improves objective symmetry and patient satisfaction in non-flaccid facial palsy. The lack of change in emotional expression may reflect improved symmetry at the cost of dynamic muscle activation.