Stroke rehabilitation using noninvasive cortical stimulation: hemispatial neglect

Abstract

The rehabilitation of neuropsychological sequels of cerebral stroke such as hemispatial neglect by noninvasive cortical stimulation (NICS) attracts increasing attention from the scientific community. The NICS techniques include primarily repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). They are based on the concept of either reactivating a hypoactive cortical region affected by the stroke (the right hemisphere in case of neglect) or reducing cortical hyperactivity of the corresponding cortical region in the contralateral hemisphere (the left hemisphere). In the studies published to date on the topic of neglect rehabilitation, rTMS was used to inhibit the left parietal cortex and tDCS to either activate the right or inhibit the left parietal cortex. Sham-controlled NICS studies assessed short-term effects, whereas long-term effects were only assessed in noncontrolled rTMS studies. Further controlled studies of large series of patients are necessary to determine the best parameters of stimulation (including the optimal cortical target location) according to each subtype of neglect presentation and to the time course of stroke recovery. To date, even if there are serious therapeutic perspectives based on imaging data and experimental studies, the evidence is not compelling enough to recommend any particular NICS protocol to treat this disabling condition in clinical practice.

The effect of transcranial direct current stimulation of the motor cortex on exercise-induced pain

“…In the experimental session, the current was applied with an intensity of 2.0 mA for 10 min, whereas during the SHAM session stimulation lasted 30 s and subsequently ramped down to no stimulation. This induced the slight itching sensation which is commonly experienced during tDCS at the beginning of the stimulation, but has been shown to produce no cortical changes Mylius et al 2012). Participants were blinded as to the polarity of tDCS and the SHAM and EXP conditions.…”

Modulation of attention functions by anodal tDCS on right PPC

“…The finding of an asymmetry in the effects of tDCS on visual field (rPPC tDCS enhanced network efficiency for targets presented in the lVF along with a decline of network efficiency for targets presented on the rVF) is important as the concept of interhemispheric rivalry (Kinsbourne, 1977) is so far the most common basis for the application of non-invasive brain stimulation to modulate neglect (Müri et al, 2013). Even though the existing evidence for a therapeutic effect of tDCS is not yet explicit enough to recommend a particular tDCS protocol for clinical application (Mylius et al, 2012), a systematic investigation of optimal stimulation parameters for tDCS in the neurorehabilitation of attention deficits is warranted (Hesse et al, 2011).…”

Noninvasive Brain Stimulation for Treatment of Right- and Left-Handed Poststroke Aphasics

“…NIBS can modulate the excitability and activity of targeted cortical regions and thereby alter the interaction within pathologically affected functional networks; this kind of intervention might promote the adaptive cortical reorganization of the language network after stroke [9,10,19,20,21]. Since recovery from poststroke aphasia seems to be more effective in patients who recover function in the left inferior frontal gyrus (IFG), NIBS trials aimed to activate this region: this effect can be achieved by excitatory NIBS (high-frequency repetitive transcranial magnetic stimulation, rTMS; intermittent theta burst stimulation; anodal transcranial direct current stimulation, tDCS) to reactivate the perilesional area or by inhibitory NIBS (low-frequency rTMS or cathodal tDCS) to reduce increased activities in the contralesional homologous areas (review in Mylius et al [21]).…”

“…Since recovery from poststroke aphasia seems to be more effective in patients who recover function in the left inferior frontal gyrus (IFG), NIBS trials aimed to activate this region: this effect can be achieved by excitatory NIBS (high-frequency repetitive transcranial magnetic stimulation, rTMS; intermittent theta burst stimulation; anodal transcranial direct current stimulation, tDCS) to reactivate the perilesional area or by inhibitory NIBS (low-frequency rTMS or cathodal tDCS) to reduce increased activities in the contralesional homologous areas (review in Mylius et al [21]).…”

“…They showed favorable effects in speech performance for several weeks to a few months [reviews in [21,27]]. Only one study coupled ipsilesional anodal tDCS to language therapy in chronic nonfluent aphasia and observed improved speech/language performance for 1 week to 2 months [28].…”