Single Sessions of High-Definition Transcranial Direct Current Stimulation Do Not Alter Lower Extremity Biomechanical or Corticomotor Response Variables Post-stroke

• Published in: Frontiers in neuroscience Vol. 13; p. 286
• Main Authors: Kindred, John Harvey, Kautz, Steven A, Wonsetler, Elizabeth Carr, Bowden, Mark Goodman
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Research Foundation 11.04.2019; Frontiers Media S.A
• Subjects: anodal; Biomechanics; Brain research; cathodal; Cerebral hemispheres; Cortex (motor); Electrodes; Gait; HD-tDCS; Health sciences; Kinematics; Latency; Magnetic fields; mobility; Motion capture; Motor evoked potentials; Muscles; Neuroscience; Parameter estimation; Physical therapy; Rehabilitation; Skeletal muscle; Stroke; Studies; tDCS; Transcranial magnetic stimulation; Canada; United States > US; Montreal Quebec Canada; brain stimulation; cathodal; mobility; anodal; gait; tDCS; HD-tDCS; TMS
• ISSN: 1662-4548; 1662-453X; 1662-453X
• DOI: 10.3389/fnins.2019.00286

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique used to modulate cortical activity. However, measured effects on clinically relevant assessments have been inconsistent, possibly due to the non-focal dispersion of current from traditional two electrode configurations. High-definition (HD)-tDCS uses a small array of electrodes ( = 5) to improve targeted current delivery. The purpose of this study was to determine the effects of a single session of anodal and cathodal HD-tDCS on gait kinematics and kinetics and the corticomotor response to transcranial magnetic stimulation (TMS) in individuals post-stroke. We hypothesized that ipsilesional anodal stimulation would increase the corticomotor response to TMS leading to beneficial changes in gait. Eighteen participants post-stroke (average age: 64.8 years, : 12.5; average months post-stroke: 54, : 42; average lower extremity Fugl-Meyer score: 26, : 6) underwent biomechanical and corticomotor response testing on three separate occasions prior to and after HD-tDCS stimulation. In a randomized order, anodal, cathodal, and sham HD-tDCS were applied to the ipsilesional motor cortex for 20 min while participants pedaled on a recumbent cycle ergometer. Gait kinetic and kinematic data were collected while walking on an instrumented split-belt treadmill with motion capture. The corticomotor response of the paretic and non-paretic tibialis anterior (TA) muscles were measured using neuronavigated TMS. Repeated measures ANOVAs using within-subject factors of time point (pre, post) and stimulation type (sham, anodal, cathodal) were used to compare effects of HD-tDCS stimulation on measured variables. HD-tDCS had no effect on over ground walking speed ( > 0.41), or kinematic variables ( > 0.54). The corticomotor responses of the TA muscles were also unaffected by HD-tDCS (resting motor threshold, = 0.15; motor evoked potential (MEP) amplitude, = 0.25; MEP normalized latency, = 0.66). A single session of anodal or cathodal HD-tDCS delivered to a standardized ipsilesional area of the motor cortex does not appear to alter gait kinematics or corticomotor response post-stroke. Repeated sessions and individualized delivery of HD-tDCS may be required to induce beneficial plastic effects. Contralesional stimulation should also be investigated due to the altered interactions between the cerebral hemispheres post-stroke.