A combined transcranial direct current stimulation and virtual reality-based intervention on upper limb function in chronic stroke survivors with severe hemiparesis

Rehabilitation options for stroke survivors who present severe hemiparesis in chronic stages are limited and may end in compensation techniques that involve the use of the less affected arm to achieve some degree of functional independence. Passive mobilization, mirror therapy, or motor imagery are the scant alternatives that try to involve the hemiparetic arm into the rehabilitation process. Transcranial direct current stimulation (tDCS) is a non-invasive technique that has been used after stroke to promote excitability of the surviving neural architecture in order to support functional recovery. Interestingly, cortical excitability has been reported to increase when tDCS is combined with virtual reality. This synergetic effect could explain the promising results achieved by preliminary experimental interventions that combined both approaches on upper limb rehabilitation after stroke. However, the efficacy of these interventions in subjects with severe hemiparesis has not been explored, at least in part, because their restriction of movements may limit their interaction with common virtual reality systems. We present a tDCS enhanced virtual reality-based intervention that enables interaction and multimodal stimulation of subjects with severe hemiparesis after stroke and evaluate its efficacy in seven chronic participants. Results showed clinically important improvement in the body functions and activities after the intervention, and a maintenance of gains weeks after. Although further studies are needed, the efficacy of this intervention is promising.