373 The Use of Botulinum Toxin to Improve Cosmesis in Patients with Facial Asymmetry Following Facial palsy/synkinesis

Abstract Aim Facial Palsy (FP) is a common, debilitating condition with a broad range of aetiologies. It causes unilateral paralysis, functional impairments, and asymmetry resulting in overall reduced facial aesthetics. Secondary complications like hyperkinesis or synkinesis can result in a reduced quality of life, including social isolation and deteriorating mental health. Treatments, including botulinum toxin (BTX) injections, aim to correct this asymmetry. This review assesses BTX's efficacy, safety, and cost-effectiveness for enhancing facial symmetry in FP. Method PubMed was used to find studies that analysed BTX’s effects and outcomes on patients with FP and its resulting complications. Only studies from 2010 to 2022 in English were included. A total of 16 studies were identified. Results Intramuscular injections of BTX are a beneficial long-term treatment for individuals with FP. BTX reduces hyperkinesis, synkinesis and enhances facial symmetry, leading to better cosmesis and improved overall quality of life. The amount of toxin required ranges from 0.5-17 units depending on the muscle targeted with platysma requiring the most amount of toxin. When treating both sides of the face, the normal side requires more toxin compared to the affected side. Limited evidence was found to suggest BTX's potential in acute FP. Therapeutic effects ranged between 1-21 days, lasting about 4 months, requiring safe, periodic repetition. Adverse effects were found to be mild, transient, and rare with no severe complications or toxin resistance reported. Conclusions BTX can be considered a safe and effective treatment to improve facial symmetry and overall cosmesis in the long-term management of patients with facial palsy.