Transcranial Direct Current Stimulation of the Motor Cortex in Essential Tremor

Overview

The current research is aimed at using Transcranial Direct Current Stimulation (tDCS) as complementary therapeutic tool in the treatment of essential tremor. Patients will be randomized into two groups (tDCS-cathode vs. tDCS-sham) according to detailed protocol. Main outcome will be measured by the change in tremor amplitude using an accelerometer pre and post cathodal tDCS of the motor cortex. A total of 40 patients ought to be enrolled as specified in methodology. Secondary outcomes will assess TRG essential tremor rating assessment scale (TETRAS) as well as clinical monitoring.

Essential tremor (ET) is a common progressive neurological disorder and is the most common movement disorder. Worldwide , up to 5% of the population suffer from this disorder with an increased incidence with advanced age. The proposed mechanism that underlies ET, the central oscillating network, is mainly composed of the olivocerebellar system, thalamus and motor cortex. An interruption in this circuit limits the ability of the cortex to reorganize and restore ET. a case of 76 year old female with essential tremor that disappeared following a cortico-subcortical prerolandic stroke despite complete motor recovery highlights the role of the motor cortex in the production and possible therapeutic role of the transcranial direct current stimulation. Study design A randomized, sham-controlled, double blind and crossover study. Study procedure: The first visit is an inclusion visit Prior to starting the first tDCS session, the patient will be asked to fill his/her first TRG essential tremor assessment (TETRAS) scale. The physician will then quantitatively analyze the tremor on the most affected side using an accelerometer. Cathodal tDCS will be administered on the area representing the primary motor cortex and the anode over the contralateral supraorbital area. tDCS stimulation (cathodal and sham) will be done daily for 5 consecutive days during weeks 1 and 5. Each stimulation session will last 30 minutes. tDCS will be performed while the patient is at rest, without any concurrent cognitive or motor task.The two tDCS sessions will be separated by a 23 day washout period. Patient will be asked to fill out their TETRAS at days 1 and 5 of each tDCS session (cathodal and sham), and days 12 and 19 after each tDCS session (cathodal and sham). Accelerometer assessment of the tremor will be performed at days 1 and 5 of each tDCS stimulation session (cathodal and sham).