Pilot efficacy and tolerability: a randomized, placebo-controlled trial of levetiracetam for essential tremor

The purpose of this pilot single-site study was to assess efficacy and safety of levetiracetam for essential tremor, using a placebo-controlled, double-blind, randomized crossover design with an interim analysis planned after completion of the first 10 to 15 subjects. The study was designed to detect a mean 30% reduction in composite tremor score, comparable to that of primidone or propranolol, which can be demonstrated with 30 or fewer subjects. Each treatment arm included baseline tremor assessments, a 4-week medication titration, 2 weeks of stable dose, and treatment tremor assessments. Levetiracetam was titrated to 3,000 mg/day or to a lower maximal tolerated dose. The median age was 72 years, with 28 years median tremor duration. There was no statistically significant difference in response between placebo and levetiracetam on any tremor rating scale or accelerometry measure. The 95% confidence interval for the true mean difference between placebo and levetiracetam treatments was +18.5 to -22.5%, which excludes the minimum 30% drop required to consider levetiracetam clinically effective to a degree comparable to primidone or propranolol. Whether levetiracetam has lesser-degree antitremor efficacy was not addressed in this pilot study.