Effects of non-invasive cortical stimulation on skilled motor function in chronic stroke

Abstract

Stroke is a leading cause of adult motor disability. Despite recent progress, recovery of motor function after stroke is usually incomplete. This double blind, Sham-controlled, crossover study was designed to test the hypothesis that non-invasive stimulation of the motor cortex could improve motor function in the paretic hand of patients with chronic stroke. Hand function was measured using the Jebsen-Taylor Hand Function Test (JTT), a widely used, well validated test for functional motor assessment that reflects activities of daily living. JTT measured in the paretic hand improved significantly with non-invasive transcranial direct current stimulation (tDCS), but not with Sham, an effect that outlasted the stimulation period, was present in every single patient tested and that correlated with an increment in motor cortical excitability within the affected hemisphere, expressed as increased recruitment curves (RC) and reduced short-interval intracortical inhibition. These results document a beneficial effect of non-invasive cortical stimulation on a set of hand functions that mimic activities of daily living in the paretic hand of patients with chronic stroke, and suggest that this interventional strategy in combination with customary rehabilitative treatments may play an adjuvant role in neurorehabilitation.

Multiple sessions of transcranial direct current stimulation and upper extremity rehabilitation in stroke: A review and meta-analysis

“…Several clinical trials involving participants with stroke have also reported highly variable responses (Hummel et al, 2005;Bolognini et al, 2011;Hesse et al, 2011;Khedr et al, 2013). Thus one important future consideration may be to determine which patients with stroke are most likely to benefit.…”

“…Thus a number of approaches are now being investigated in an attempt to increase the effectiveness of stroke rehabilitation techniques for the UE. Non-invasive methods of brain stimulation such as transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) are extensively researched and are beginning to be used clinically to modulate brain activity (Paulus, 2003;Pascual-Leone et al, 2000;Hummel et al, 2005). Although these two methods have very different modes of action (rTMS stimulates axons in the brain and initiates new action potentials; tDCS polarises the neurones, and modulates their ongoing firing pattern) both of them, when applied over the motor cortex, produce changes in cortical excitability which, in the case of tDCS can last up to 90 min Paulus, 2000, 2001;Fitzgerald et al, 2006).…”

“…From a practical viewpoint, anodal tDCS is usually assumed to increase excitability whereas cathodal tDCS reduces excitability (Nitsche and Paulus, 2000). In stroke rehabilitation this means that researchers will employ anodal tDCS over the stroke hemisphere to improve the response of that hemisphere to training protocols (Hummel et al, 2005). Alternatively, employing the logic of inter-hemispheric imbalance, cathodal stimulation of the non-stroke hemisphere will inhibit that hemisphere to reduce its trans-hemispheric inhibition of the affected hemisphere or bihemispheric stimulation by simultaneously modulating the unaffected and affected motor cortex (Nitsche et al, 2003a;Lindenberg et al, 2010).…”

Invasive Neurostimulation in Stroke Rehabilitation

“…tDCS, depending on the polarity, can also enhance (anodal) or suppress (cathodal) excitability of the targeted cortex [43]. Studies have generally downregulated contralesional activity using low-frequency rTMS [44] or cathodal tDCS [45], or upregulated ipsilesional activity using high-frequency rTMS [46] or anodal tDCS [47], or simultaneously applied both [48,49].…”

La stimulation transcrânienne à courant continu : un nouvel outil de neurostimulation

“…Les effets ont é té observé s lors des stimulations anodiques du cortex moteur lé sé . La ré alisation d'une stimulation anodique de M1 de la main a mis en é vidence une amé lioration de la force, de la dexté rité et de la vitesse de ré action de la main paré tique (Hummel et al, 2005). L'effet de la tDCS sur les membres infé rieurs se traduit é galement par une augmentation de la force à la suite d'une stimulation anodique (Tanaka et al, 2011).…”