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Description
Stroke is a leading cause of disability worldwide. Seeking new therapeutic options is mandatory for improving existing motor rehabilitation techniques to obtain a better motor recovery.
Stroke patients undergo some spontaneous degree of functional recovery; this process may occur even beyond the resolution of acute changes and could be due to the reorganization of remaining neural circuits. This reorganization falls into the concept of plasticity that could be defined as any enduring change in cortical properties. Plasticity is continuously modified by experience and learning and seems to be enhanced after brain lesions.
In the last decades, plasticity of human brain after a lesion has been studied in vivo by means of non invasive brain stimulation (NIBS): neurophysiologic and biologic substrate of plasticity should provide a rational basis for tailoring specific strategies for therapeutic intervention for stroke recovery.
It can be hypothesized that shaping reorganization in the adjacent intact cortex, and contralateral healthy hemisphere could facilitate functional recovery of the brain after stroke. NIBS can modulate cerebral cortex excitability not invasively and seem to be a promising tool for driving plasticity in damaged brain.
To this aim, we tested whether the application of NIBS, following different theoretical models and applied in different stages after a stroke, could enhance motor recovery in upper limb.
Our studies demonstrated that NIBS, by means of repetitive TMS or tDCS, could be considered a safe procedure to apply in stroke patients both in the acute and chronic phases. On the other hand, we demonstrated that NIBS are able to change motor cortex excitability in stroke patients toward an inter-hemispheric re-balance when applied to increase stroke hemisphere excitability (or decrease unaffected hemisphere excitability)
Furthermore, although larger and multi-centric studies are warranted to draw stronger conclusions, the induction of metaplasticity in the affected hemisphere by means of inhibitory protocols could be considered as a useful and promising tool to restore learning and improve motor function also years after a stroke.
References
1. Di Lazzaro V, Dileone M, Capone F, Pellegrino G, Ranieri F, Musumeci G, Florio L, Di Pino G, Fregni F. Immediate and late modulation of interhemipheric imbalance with bilateral transcranial direct current stimulation in acute stroke.
Brain Stimul. 2014 Nov-Dec;7(6):841-8.
2. Di Lazzaro V, Rothwell JC, Talelli P, Capone F, Ranieri F, Wallace AC, Musumeci G, Dileone M. Inhibitory theta burst stimulation of affected hemisphere in chronic stroke: A proof of principle, sham-controlled study. Neurosci Lett. 2013 Oct 11;553:148-52.
3. Talelli P, Wallace A, Dileone M, et al Theta Burst Stimulation in the Rehabilitation of the Upper Limb: A Semirandomized, Placebo-Controlled Trial in Chronic Stroke Patients.
Neurorehabil Neural Repair. 2012 Oct;26(8):976-87.
