A Cochrane review included 3 studies with a total of 309 subjects. Included patients had a definite upper-limb essential tremor according to criteria proposed by Tremor Investigation Group. Age ranged between 18 and 80 years. The treatment time varied between 2 and 24 weeks. The co-therapy (mainly beta-blockers, benzodiazepine and primidone) was maintained throughout the study period. Compared to placebo, patients treated with topiramate showed a significant improvement in functional disability and an increased risk of withdrawal (RR 1.78, 95% CI 1.23 to 2.60; 2 studies, n=285). There were more adverse events for topiramate-treated patients, particularly paraesthesia, weight loss, appetite decrease and memory difficulty.
Comment: The quality of evidence is downgraded by study quality (lack of allocation concealment, high drop-out rate), imprecise results (few studies in comparisons) and indirectness (short follow-up time).