The use of botulinum toxin to improve cosmesis in patients with facial asymmetry following facial palsy/synkinesis - A literature review.

Facial palsy (FP) is a common debilitating condition with many etiologies. FP causes unilateral paralysis, functional impairments, and asymmetry, reducing aesthetics overall. Secondary complications such as hyperkinesis or synkinesis can result in reduced quality of life (QoL), including social isolation and deteriorating mental health. Treatments, including botulinum toxin injections, aim to correct this asymmetry. This review assessed the efficacy, safety, and cost effectiveness of botulinum for enhancing facial symmetry in FP. A PubMed search was conducted for studies from 2010 to 2023. Studies that analyzed the effects of botulinum on patients with FP and its resulting complications were selected. A total of 16 studies were included. These studies proved botulinum to be beneficial in the long-term treatment of individuals with FP. It reduces facial asymmetry, leading to improved facial aesthetics and overall QoL. Limited evidence was found to suggest botulinum's potential in acute FP. Therapeutic effects were observed within 1 to 21 days, lasting ∼4 months, requiring safe, periodic repetition. Adverse effects were mild, transient, and rare, with no reported severe complications or cases of toxin resistance. Botulinum can be considered safe and effective when used to improve facial symmetry and overall cosmesis in the long-term management of patients with FP. However, there is a lack of studies, especially on those with higher levels of evidence on the use of botulinum in acute FP treatment. Therefore, further research is required to standardize the ideal timing, optimum dosage, and treatment interval.