A non-invasive tool for brain-plasiticity-based therapy: Transcranial magnetic stimulation in post-stroke rehabilitation

Stroke is the third most common cause of death and the commonest cause of chronic disability, and its effects can reflect in disabilities of many activities of daily life and in losses of brain functions. The mechanisms subtending post-stroke recovery are complex and operating at different levels, from molecular to synaptic and network reorganization. This reorganization largely subtends clinical recovery of motor performances and sensorimotor integration after a stroke. Noninvasive brain stimulation modalities such as transcranial magnetic stimulation allow researchers to study human brain activity in real time, characterize balance of excitation and inhibition, and ultimately guide plastic changes. A growing body of evidence is converging on the possibility that transcranial magnetic stimulation (TMS) induces an exogenous plastic rearrangement of synaptic efficacy in the stimulated network. Once integrated with robotic rehabilitation treatments, transcranial magnetic stimulation can be used to modulate in a targeted fashion neuronal assemblies for improving patients motor performance. A correct correlation of the data coming from the two, objective, rehabilitative/measuring systems, one at the neural level (TMS) and one at the motor level (robot) could provide rich multimodal information on patient's undergoing recovery well before it becomes apparent to a human eye and more precisely documented than with the clinical scales, and could support early corrective strategies on the robotic treatment. The present paper presents a review of the effects of TMS on stroke recovery and suggests a possible integration of this technique with robotic rehabilitation protocols.