Journal Article

Modulation of brain plasticity in stroke: a novel model for neurorehabilitation

Rothwell, John C., Formica, Domenico, Ferreri, Florinda, Assenza, Giovanni, Di Pino, Giovanni, Tombini, Mario, Di Lazzaro, Vincenzo, Pellegrino, Giovanni, Capone, Fioravante, Ranieri, Federico, Ziemann, Ulf

2014

Overview

Key Points Noninvasive brain stimulation (NIBS) is a promising approach to enhance recovery after stroke, but its beneficial effect is limited and the technique is not yet ready for broad clinical use We suggest that the disappointments in NIBS trials are related to over-reliance on the interhemispheric competition and vicariation models of recovery, which are oversimplified and do not apply to all patients with stroke The concept of 'structural reserve' integrates the effects that interhemispheric inhibition and vicariation exert on the unlesioned residual network We propose a unified 'bimodal balance–recovery model' that takes into account this individual residual network The model could be used to tailor treatment for individual patients and increase the efficacy of NIBS in stroke rehabilitation Noninvasive brain stimulation (NIBS) is a promising approach for facilitating recovery of motor function after stroke, but trials assessing its efficacy have provided contradictory results. Di Pino and colleagues propose a unified 'bimodal balance–recovery model' for stroke recovery that takes into account the individual residual structural reserve and could aid tailoring of treatment for individual patients, thereby increasing the efficacy of NIBS in stroke rehabilitation. Noninvasive brain stimulation (NIBS) techniques can be used to monitor and modulate the excitability of intracortical neuronal circuits. Long periods of cortical stimulation can produce lasting effects on brain function, paving the way for therapeutic applications of NIBS in chronic neurological disease. The potential of NIBS in stroke rehabilitation has been of particular interest, because stroke is the main cause of permanent disability in industrial nations, and treatment outcomes often fail to meet the expectations of patients. Despite promising reports from many clinical trials on NIBS for stroke recovery, the number of studies reporting a null effect remains a concern. One possible explanation is that the interhemispheric competition model—which posits that suppressing the excitability of the hemisphere not affected by stroke will enhance recovery by reducing interhemispheric inhibition of the stroke hemisphere, and forms the rationale for many studies—is oversimplified or even incorrect. Here, we critically review the proposed mechanisms of synaptic and functional reorganization after stroke, and suggest a bimodal balance–recovery model that links interhemispheric balancing and functional recovery to the structural reserve spared by the lesion. The proposed model could enable NIBS to be tailored to the needs of individual patients.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 631/1647/1453/2105 / 692/699/375/534 / 692/700/565/491 / Brain - physiology / Brain - physiopathology / Brain research / Brain stimulation / Care and treatment / Clinical trials / Humans / Hypoxia / Medicine & Public Health / Methods / Models, Theoretical / Neurology / Neuronal Plasticity - physiology / Patient outcomes / Physical therapy / Recovery of Function / review-article / Stroke / Stroke (Disease) / Stroke - physiopathology / Stroke Rehabilitation / Transcranial Direct Current Stimulation - methods / Transcranial magnetic stimulation / Transcranial Magnetic Stimulation - methods