Effectiveness of cerebellar repetitive transcranial magnetic stimulation in essential tremor: study protocol for a randomized, sham-controlled trial

Background: Recent studies have shown that the cerebellum has a significant role in development of essential tremor and repetitive transcranial magnetic stimulation (rTMS) has therapeutic effects on its motor symptoms. Methods/Design: This is a prospective, randomized, triple-blind, sham-controlled, add-on, crossover trial involving patients with essential tremor. Thirty patients will be included and randomized to either real rTMS (900 daily pulses of rTMS over each cerebellar hemisphere) or sham stimulation (low current electrical stimulation). After 2 months of follow-up, patients will undergo crossover and receive the other treatment. For the primary outcome measure, patients will be assessed using Fahn-Tolosa-Marin scale. Adverse events will be assessed as the secondary outcome measure. Discussion: This study evaluates the effect of cerebellar rTMS on tremor severity of patients afflicted with essential tremor, and aims to address the shortcomings of previous studies using a relatively larger sample size and randomized, sham-controlled, crossover design. Trial registration: This trial has been registered at ClinicalTrials.gov (identifier: NCT02704793) on 5 March 2016 and also at Iranian Registry of Clinical Trials (IRCT) (registration ID: IRCT2015100824428N1) on 1 April 2016. Ethics: This study has been approved by the Research Ethics Committee of Mashhad University of Medical Sciences, Iran (approval number: ir.mums.sm.rec.1394.353). Informed consent: Written informed consent will be obtained from all participants.