Category: Stroke; Neuroplasticity (includes neuroscience)
Objective : To determine if cathodal and anodal tDCS would yield differential effects depending on presence or absence of motor evoked potentials (MEP +, MEP-), measured with transcranial magnetic stimulation at baseline.
Design : Double-blind feasibility study
Setting : Outpatient Neurorehabilitation Research Clinic
Participants (or Animals, Specimens, Cadavers) : A convenience sample of 10 chronic stroke participants with severe motor deficit. Chronic was defined as occurring more than12 months from stroke onset. Severe motor deficit was defined as Fugl-Meyer Assessment (FMA) score between 7 and 34 as well as the inability to extend the affected metacarpophalangeal joints at least 10° and the wrist 20°.
Interventions : Each participant received 10 days of either cathodal or anodal tDCS (2.0 mA, 20 minutes) paired with 2 hours of motor therapy. Motor therapy focused on skill acquisition via activities to improve functional use of the impaired UE.
Main Outcome Measure(s) : Action Research Arm Test (ARAT) was collected at baseline, after completion of intervention, and 1-month follow-up.
Results : Mean changes in ARAT were 7.0, 2.5, 2.0, and 1.7 for Cathodal/MEP -, Cathodal/MEP +, Anodal/MEP -, and Anodal/MEP +, respectively. By follow up, MEP + participants maintained their improvement, regardless of receiving anodal or cathodal tDCS. However, MEP - participants receiving anodal tDCS lost all improvement, while those who received cathodal tDCS maintained their improvements.
Conclusions : Cathodal tDCS appears to be particularly beneficial in participants without MEP at baseline. Larger prospective and randomized studies are required to substantiate these preliminary findings.