[Note: Transcranial direct current brain stimulation (tDCS) involves constant low electromagnetic current delivered to a part of the brain via two small electrodes/pads, one placed on the head near the ‘region of interest’ and the other in another location to complete a circuit. It modulates the ‘excitability’ of neurons in target areas of the brain – either up (anodal tDCS) or down (cathodal tDCS). In this "bihemispheric" tDCS study, neurons in the damaged half of the brain were upregulated while those in the undamaged half were downregulated.]
Objective: Motor recovery after stroke depends on the integrity of ipsilesional motor circuits and interactions between the ipsilesional and contralesional hemispheres [the half of the brain tha stroke damage and the half away from the damage]. In this sham-controlled randomized trial, we investigated whether noninvasive modulation of regional excitability of bilateral motor cortices in combination with physical and occupational therapy improves motor outcome after stroke.
Methods: Twenty chronic stroke patients were randomly assigned to receive 5 consecutive sessions of either:
1. Bihemispheric transcranial direct current stimulation (tDCS) (anodal tDCS to upregulate excitability of ipsilesional motor cortex and cathodal tDCS to downregulate excitability of contralesional motor cortex) with simultaneous physical/occupational therapy or
2. Sham [fake] stimulation with simultaneous physical/occupational therapy.
Changes in motor impairment (Upper Extremity Fugl-Meyer) and motor activity (Wolf Motor Function Test) assessments were outcome measures while functional imaging parameters were used to identify neural correlates of motor improvement.
Results: The improvement of motor function was significantly greater in the real stimulation group (20.7% in Fugl-Meyer and 19.1% in Wolf Motor Function Test scores) when compared to the sham group (3.2% in Fugl-Meyer and 6.0% in Wolf Motor Function Test scores).
The effects outlasted the stimulation by at least 1 week. In the real-stimulation group, stronger activation of intact ipsilesional motor regions during paced movements of the affected limb were found postintervention whereas no significant activation changes were seen in the control group.
The combination of bihemispheric tDCS and peripheral sensorimotor activities improved motor functions in chronic stroke patients that outlasted the intervention period.
This novel approach may potentiate cerebral adaptive processes that facilitate motor recovery after stroke.
Classification of evidence:
This study provides Class I evidence that for adult patients with ischemic stroke [caused by blockage] treated at least 5 months after their first and only stroke, bihemispheric tDCS and simultaneous physical/occupational therapy given over 5 consecutive sessions significantly improves motor function as measured by the Upper Extremity Fugl-Meyer assessment (raw change treated 6.1 ± 3.4, sham 1.2 ± 1.0).
Source: Neurology, Dec 14, 2010;75(24)pp 2176-84. Lindenberg R, Renga V, Zhu LL, Nair d, Schlaug G. Department of Neurology, Beth Israel Deaconess Medical Center and harvard Medical School, Boston, Massachusetts, USA. [Email: email@example.com]