Effectiveness, safety, and quality of life outcomes of neurotoxin injections in the treatment of essential tremors: a systematic review

Abstract

Essential tremor (ET) is a chronic, progressive condition classically affecting the hands and arms, is typically bilateral, and may be asymmetric. Tremor related disability can impact mood and quality of life. Disease progression and patient related factors may limit efficacy and use of traditional pharmacologic options. Botulinum neurotoxin (BoNT) injections have been explored as an alternative treatment option. This systematic review aims to evaluate the efficacy and safety of BoNT injections as a therapeutic intervention for essential tremors. Following PRISMA guidelines, a systematic literature search was conducted on PubMed, Cochrane, HERDIN, and ScienceDirect on March 2025. The following search string was used ("Essential tremor" OR "tremor disorder") AND ("botulinum toxin" OR "neurotoxin" OR "botulinum toxin A" OR "BoNT-B") AND ("efficacy" OR "safety" OR "treatment"). All articles published prior to March 2025 were included. Of 9121 records, 18 studies were included in the final analysis: eight open label studies, five randomized clinical trials, three retrospective studies, and two prospective crossover studies. The studies looked at ET manifesting as upper limb tremor (n = 12), voice tremor (n = 4), and head tremor (n = 2). Among patients receiving BoNT, majority experienced reduction in tremor amplitude and severity and improvement in quality-of-life. Adverse effects were generally dose-dependent and tolerable. Muscle weakness was reported from injections in the upper limb. Hoarseness, breathiness, coughing/choking, dysphagia, and jaw weakness were mostly reported from injections for voice tremors. Lastly, headache, dizziness and dry skin were reported from injections for head tremors. BoNT injections demonstrated effectiveness in reducing tremor severity and is a promising approach for those experiencing symptoms that are refractory to conventional oral medications. Further controlled trials are necessary to confirm these observations.

Keywords: Botulinum neurotoxin type A (botulinum toxin A); Botulinum toxin; Essential tremors; IncobotulinumtoxinA; Neurotoxin; OnabotulinumtoxinA.