Botulinum toxin treatment of the buccinator muscle facial synkinesis: A systematic review.

[BACKGROUND] The purpose of this review is to provide an overview of the available literature assessing the treatment of botulinum toxin injections for the treatment of synkinesis of the buccinator muscle in patients with peripheral facial palsy (PFP).

[MATERIALS AND METHODS] A multi database search was performed, including the following databases: Pubmed, Medline, Embase, and the Cochrane Library. Each database was searched from its earliest date until 8 June 2023. The following outcome measures were extracted from the articles when available: subjective, somatic, and psychological effects on the patients and objective outcomes such as the House-Brackmann, Sunnybrook and Sydney scores. The methodological quality of the included studies was rated using the Newcastle-Ottawa scale for nonrandomised trials.

[RESULTS] The primary literature search generated 37 articles. After removing duplicates, 25 articles remained for abstract appraisal, of which 20 underwent full-text appraisal, resulting in 3 studies for analysis. All of these studies showed (significant) improvement in synkinesis either measured using the Synkinesis Assessment Questionnaire or subjectively measured by asking treated patients.

[CONCLUSION] The available literature supports the finding that botulinum toxin treatment of the buccinator muscle could be a welcome addition to facial synkinesis treatment and could significantly improve patient outcomes. In future studies, the efficacy of EMG-guided buccinator injections, optimal dose, and a validated measuring method could be beneficial in optimising treatment for patients with a PFP and synkinesis.