Background and purpose: Sialorrhea often happens in patients with neurologic disorders, and botulinum toxin (BoNT), which inhibits acetylcholine activation, may be an effective treatment for drooling. This systematic review and meta-analysis of randomized control trials aims to evaluate the efficacy and safety of BoNT in adults and children with sialorrhea due to neurological disorders. Methods: The PubMed, Embase, and Cochrane databases were searched for relevant studies published before August 2021. The pooled estimate of outcomes was calculated using a random effect model. Results: The review included 17 studies involving 981 patients. Compared with placebo, both BoNT type A (BoNT-A) and BoNT type B (BoNT-B) alleviated drooling frequency and severity (mean difference, 95% CI; BoNT-A: −1.20, −1.89 to −0.51; BoNT-B: −1.62, −2.07 to −1.17), reduced saliva weight (BoNT-A: −1.70, −2.30 to −1.10; BoNT-B: −1.12, −1.97 to −0.27), and improved global impression of change (BoNT-A: −1.30, −1.73 to −0.86; BoNT-B: −1.58, −1.95 to −1.21) in adults 4 weeks postinjection. BoNT-B remained effective at 12 weeks. In children, BoNT-A and BoNT-B alleviated sialorrhea symptoms (BoNT-A: −1.63, −2.42 to −0.85; BoNT-B: −5.20, −6.03 to −4.37) and BoNT-A reduced saliva weight (−0.77, −1.54 to 0.00) at 4 weeks postinjection. After 12 weeks, BoNT-B remained efficacious. Most adverse effects (AEs) were mild to moderate and self-limited. Conclusions: There is moderate certainty of evidence (COE) that either BoNT-A or BoNT-B could relieve sialorrhea after 4 and 12 weeks of follow-up without significantly more severe AEs in adults. However, the COE is very low to low in children.
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