Botulinum toxin in essential hand tremor - A randomized double-blind placebo-controlled study with customized injection approach

Introduction To evaluate the safety and efficacy of incobotulinumtoxinA (IncoA) injection for treatment of essential hand tremor. In essential tremor and Parkinson's disease tremor, administration of onabotulinumtoxinA via a fixed injection approach improves the tremor but a high percentage of patients (30–70%) develop moderate to severe hand weakness which has limited its use in clinical practice. Methods This study was performed from July 2013 to July 2016 on 33 subjects. This is a double-blind, placebo-controlled, crossover trial injecting 80–120 units of IncoA into 8–14 hand and forearm muscles using a customized approach. The subjects were followed for 28 weeks. The treatment efficacy was evaluated by the Fahn Tolosa Marin tremor rating score and NIH genetic criteria for tremor severity at 4 and 8 weeks after each of the two sets of treatments. Hand strength was assessed by an ergometer. Results There was statistically significant improvement in clinical rating score of tremor at 4 and 8 weeks following the IncoA injection. Conclusion In this study, injection of IncoA treatment via a customized approach improved essential tremor on the clinical scales and patient's perception with a low occurrence of significant hand weakness.