A RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY TO EVALUATE BOTULINUM TOXIN TYPE-A IN ESSENTIAL HAND TREMOR

Twenty-five patients with hand tremor of 2 + (moderate) to 4 + (severe ) on the tremor severity rating scale were randomized to receive eithe r 50 U of botulinum toxin (BTX) type A (Allergan, Irvine, CA) or place bo injections into the wrist flexors and extensors of the dominant lim b. If patients failed to respond to the initial injection, they were e ligible to receive another injection of 100 U 4 weeks later. Rest, pos tural, and kinetic tremors were evaluated at 2- to 4-week intervals ov er a 16-week study period using tremor severity rating scales, acceler ometry, and assessments of improvement and disability. A significant i mprovement (p < 0.05) was observed on the tremor severity rating scale 4 weeks after injection in patients treated with BTX as compared with placebo, and this effect was maintained for the duration of the study , Four weeks after injection, 75% of BTX-treated patients vs. 27% of p lacebo-treated patients (p < 0.05) reported mild to moderate improveme nt (peak effect rating greater than or equal to 2). There were no sign ificant improvements in functional rating scales, although trends were observed for some items. Postural accelerometry measurements showed a greater than or equal to 30% reduction in amplitude in nine of 12 BTX -treated subjects and in one of nine placebo-treated subjects (p < 0.0 5). Although all patients treated with BTX reported some degree of fin ger weakness, no severe, irreversible, or unexpected adverse events oc curred. Chemodenervation with BTX may significantly ameliorate essenti al hand tremor in patients who fail to improve with conventional pharm acologic therapy.