Evaluation and treatment of synkinesis with botulinum toxin following facial nerve palsy.

PURPOSE: To assess the effect and efficacy of botulinum toxin type A (BTX-A) in reducing synkinesis in aberrant facial nerve regeneration (following facial paralysis). METHOD: A total of 55 sessions of BTX-A (Botox) infiltration were performed on 30 patients (23 female) with synkinesis after facial palsy. Each subject was injected with 2.5 units of BTX-A in each injection site (the sites were chosen on a case-by-case basis). The synkinetic muscles targeted include: orbicularis oculi, zygomaticus major, depressor labii inferioris, platysma, healthy frontalis and healthy corrugator supercilii. The patients were examined using the Sunnybrook Facial Grading System, both before the BTX-A treatment and after an average of 35 days. RESULTS: All 30 patients experienced improvement to the synkinesis after treatment. Total scores: median pre-BTX-A: 40; post 53 p = 0.004. Resting symmetry scores: mean pre-BTX-A -7.1; post: -3.5; median pre -5 [interquartile range (IQR) -10 to -5]; post: -5 (IQR -5 to 0); p = 0.0001. Symmetry of voluntary movement median pre-BTX-A: 56 post 60 p = 0.10. Synkinesis scores: median pre-BTX-A: -9 post -3 p < 0.0001. Mean duration of improvement was 4 months. CONCLUSIONS: BTX-A injection treatment was effective in reducing facial synkinesis, thus improving facial expression symmetry both at rest and in voluntary movements.