Investigating Transcranial Direct Current Stimulation in Post-Stroke Motor Recovery: Advance Study from Phase I to Phase II

Abstract

Transcranial Direct Current Stimulation (tDCS) is a non-invasive format of neuro-modulation tool that can modulate cortical excitability and induce clinical changes in stroke patients with motor impairment. The optimal dose of tDCS is unknown and has been investigated. A meta-analysis suggests there is a dose-response relationship between current density and motor impairment reduction in stroke patients which high dose may leads to better efficacy. It was further proved that high dose correlates with strong electrical field strength in human brain in vivo. A phase I safety and tolerability study demonstrates that it is safe and tolerable to escalate dose/ current to 4mA in stroke patient. A 12-center phase II dose selection clinical trial titled “TRANScranial direct current stimulation for POst-stroke motor Recovery—a phase II sTudy (TRANSPORT2)” is ongoing on the NIH funded stroke trial network. This study aims to investigate the preliminary efficacy and safety and feasibility of tDCS, along with modified constraint-induced movement therapy, in first-ever ischemic stroke patients. Three dose groups will be tested including sham stimulation, low dose (2mA) and high dose (4mA) with 129 subjects. This study also investigates whether assessing the integrity of corticospinal tract by an imaging method (i.e. weighted corticospinal tract lesion load) or a neurophysiology method (i.e. presence of motor evoked potential by transcranial magnetic stimulation) can predict the therapeutic response to tDCS.