A Randomized, Double-Blind, Placebo Controlled, Crossover Trial of incobotulinumtoxinA Treatment for Upper Limb...

Proximal upper limb tremor is a common, functionally disabling condition. Medical therapy is often ineffective. IncobotulinumtoxinA can significantly improve tremor with minimal adverse effects.

We aimed to compare clinical, functional, and quality of life measures in patients with proximal upper limb tremor following incobotulinumtoxinA treatment.

We undertook a double-blind, randomized two-sequence, two-period, two-treatment, placebo-controlled cross-over trial. Twenty adult patients with proximal upper limb tremor were recruited from a tertiary movement disorders clinic. Patients were randomized 1:1 to alternate electromyographically guided intramuscular injections of either incobotulinumtoxinA or saline to the dominant upper limb using computer-generated randomization. Patients were injected at baseline, then 4 months after cross-over. Primary outcome was change in Goal Attainment Rating Scale (GARS) at two-months post intervention. Secondary outcomes were dominant upper limb The Essential Tremor Rating Assessment Scale (TETRAS), Fahn-Tolosa-Marin tremor rating scale (FTM-TRS) and three patient-related outcome measures. Outcomes were assessed at baseline and monthly intervals for 3-months post each intervention.

There was no significant improvement in the GARS at 2-months post injection (OR 1.83, 95% CI 0.14-24.32). Secondary outcomes showed a mean reduction in TETRAS score of -1.05 (95% CI -1.99 to -0.13) and FTM-TRS of -6.84 (95% CI -12.37 to -1.31) in those receiving incobotulinumtoxinA. There was no significant change in patient-rated outcome scores.

Single dose incobotulinumtoxinA injections are effective in reducing objective measures of proximal upper limb tremor and function. This did not translate into improved patient-rated outcomes in this single therapeutic dose study.