Facial Paralysis Treatment and Facial Symmetrization with Botulinum Neurotoxin: A Narrative Review with Illustrative Clinical Cases

Facial paralysis leads to static and dynamic asymmetry, hyperkinesis of the non-paralyzed side, and synkinesis, with major functional and psychosocial consequences for patients. Botulinum neurotoxin serotype A (BoNT-A) injections are an effective therapeutic option since they denervate overactive muscles, thereby reducing hyperkinesis or synkinesis and eventually improving asymmetry. This narrative review summarizes relevant literature on the use of BoNT-A for facial paralysis. It provides a summary of dosing strategies and treatment plans, discusses the use of functional scales for assessing facial paralysis and improvement after treatment, and outlines the use of electromyography (EMG) or ultrasound-guided injections to improve treatment outcomes. Finally, it discusses its potential role in the preparation for functional microsurgery. We also present the authors' anecdotal experience, with three case reports: a woman with facial paralysis caused by Ramsay Hunt Syndrome, treated with a full-face and neck BoNT-A protocol and followed-up for 18 months with photographic documentation, to further assess the aesthetic improvement; a young woman with familiarity of facial paralysis, contralateral hyperkinesis, and synkinesis, managed with EMG-guided and landmark-guided injections; and her mother, with recurrent facial paralysis and chronic synkinesis, treated with stepwise BoNT-A sessions. All three cases demonstrated clinically meaningful improvements, as evidenced by the photographic material and functional grading scores presented.