Enhancement of Rehabilitative Treatment-Dependent Functional Recovery After Stroke by Transcranial Direct Current Stimulation (tDCS)

OBJECTIVES

There is no universally accepted strategy to promote recovery of motor function after stroke, the main cause of long-term disability among adults. Neurorehabilitation contributes to recovery during the first days to weeks after stroke and later decelerates. Therefore, it is desirable to develop strategies to enhance rehabilitative effects on motor recovery particularly in the early phase after stroke in this patient group. We have recently demonstrated that cortical stimulation in the form of TMS enhances the beneficial effects of motor training and cortical plasticity in healthy volunteers and that tDCS (another noninvasive more comfortable stimulating technique than TMS transiently improves functional motor skills of the paretic hand of chronic stroke patients in the absence of training. Given the paucity of strategies available to enhance neurorehabilitation after stroke, it is now crucial to determine if tDCS can enhance the beneficial effects of customarily used rehabilitative treatment. tDCS has been used in several hundred subjects worldwide and in approximately 9 stroke patients, 15 Parkinson's disease patients and 15 healthy volunteers in our lab in the absence of undesirable side effects.

In addition to the above objectives, we will also apply functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) techniques to determine the extent of changes in neural responses and functional shift in cortical representations/reorganization as a result of the proposed intervention strategies. fMRI as a measure is important in understanding changes in brain activation prior to, during, and after motor recovery and the effects of tDCS and the rehabilitative treatment strategies under investigation. Integrating TMS together with fMRI studies will provide crucial information on the functional role of brain regions activated in neuroimaging studies in association with functional recovery.

STUDY POPULATION

We plan to study 120 patients with a single cortical or subcortical subacute stroke. Thirty healthy volunteers and a sub-group of 30 patients from the 120 patient population will also be recruited in the fMRI and TMS part of the study. The reason for including 30 patients in the fMRI and TMS components of the study is that it is anticipated that not all the 120 patients recruited in the initial study (i.e., the tDCS and therapeutic intervention phase) may be able to perform the tasks required for the fMRI part of the study and also satisfy the Exclusion criteria for fMRI scans. In addition, based on previous studies and preliminary fMRI power analysis, we estimate that 30 patients is likely to be sufficient to provide a representative sample of the patient group for the testing of the hypotheses stated in the protocol. Thirty healthy volunteers are necessary for the fMRI and TMS components of the study in order to obtain normative data for the TMS and fMRI components of the investigation. They will have the multiple number of TMS and fMRI sessions as patients in order to obtain descriptive information on the variability of these measures in both groups.