Recent findings indicate that measures derived from resting-state magnetoencephalography (rsMEG) are sensitive to cortical dysfunction in post-stroke aphasia. Spectral power and multiscale entropy (MSE) measures show that left-hemispheric areas surrounding the stroke lesion (perilesional) exhibit pathological oscillatory slowing and alterations in signal complexity. In the current study, we tested whether individually-targeted high-definition transcranial direct current stimulation (HD-tDCS) can reduce MEG abnormalities and transiently improve language performance. In eleven chronic aphasia survivors, we devised a method to localize perilesional areas exhibiting peak MSE abnormalities, and subsequently targeted these areas with excitatory/anodal-tDCS, or targeted the contralateral homolog areas with inhibitory/cathodal-tDCS, based on prominent theories of stroke recovery. Pathological MEG slowing in these patients was correlated with aphasia severity. Sentence/phrase repetition accuracy was assessed before and after tDCS. A delayed word reading task was administered inside MEG to assess tDCS-induced neurophysiological changes in relative power and MSE computed on the pre-stimulus and delay task time windows. Results indicated increases in repetition accuracy, decreases in contralateral theta (4–7 Hz) and coarse-scale MSE (slow activity), and increases in perilesional low-gamma (25–50 Hz) and fine-scale MSE (fast activity) after anodal-tDCS, indicating reversal of pathological abnormalities. RsMEG may be a sensitive measure for guiding therapeutic tDCS.

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Post-stroke aphasia is a consequence of localized stroke-related damage as well as global disturbances in a highly interactive and bilaterally-distributed language network. Aphasia is increasingly accepted as a network disorder and it should be treated as such when examining the reorganization and recovery mechanisms after stroke. In the current study, we sought to investigate reorganized patterns of electrophysiological connectivity, derived from resting-state magnetoencephalography (rsMEG), in post-stroke chronic (>6 months after onset) aphasia. We implemented amplitude envelope correlations (AEC), a metric of connectivity commonly used to describe slower aspects of interregional communication in resting-state electrophysiological data. The main focus was on identifying the oscillatory frequency bands and frequency-specific spatial topology of connections associated with preserved language abilities after stroke.RsMEG was recorded for 5 minutes in 21 chronic stroke survivors with aphasia and in 20 matched healthy controls. Source-level MEG activity was reconstructed and summarized within 72 atlas-defined brain regions (or nodes). A 72×72 leakage-corrected connectivity (of AEC) matrix was obtained for frequencies from theta to gamma (4–128 Hz). Connectivity was compared between groups, and, the correlations between connectivity and subscale scores from the Western Aphasia Battery (WAB) were evaluated in the stroke group, using partial least squares analyses. Posthoc multiple regression analyses were also conducted on a graph theory measure of node strengths, derived from significant connectivity results, to control for node-wise properties (local spectral power and lesion sizes) and demographic and stroke-related variables.Connectivity among the left hemisphere regions, i.e. those ipsilateral to the stroke lesion, was greatly reduced in stroke survivors with aphasia compared to matched healthy controls in the alpha (8-13 Hz; p=0.011) and beta (15-30 Hz; p=0.001) bands. The spatial topology of hypoconnectivity in the alpha vs. beta bands was distinct, revealing a greater involvement of ventral frontal, temporal and parietal areas in alpha, and dorsal frontal and parietal areas in beta. The node strengths from alpha and beta group differences remained significant after controlling for nodal spectral power. AEC correlations with WAB subscales of object naming and fluency were significant. Greater alpha connectivity was associated with better naming performance (p=0.045), and greater connectivity in both the alpha (p=0.033) and beta (p=0.007) bands was associated with better speech fluency performance. The spatial topology was distinct between these frequency bands. The node strengths remained significant after controlling for age, time post stroke onset, nodal spectral power and nodal lesion sizes.Our findings provide important insights into the electrophysiological connectivity profiles (frequency and spatial topology) potentially underpinning preserved language abilities in stroke survivors with aphasia.

Purpose: There are increasing demands for aphasia assessment and intervention services to be delivered remotely. The purpose of this scoping review was to address what is known about the delivery of assessments and interventions using telehealth for people with poststroke aphasia. Specifically, the review sought to (a) identify which telehealth assessment protocols have been used, (b) identify which telehealth intervention protocols have been used, and (c) describe evidence on the effectiveness and feasibility of telehealth for people with poststroke aphasia. Method: A scoping review of the literature published in English since 2013 was conducted by searching MEDLINE, Embase, PsycINFO, CINAHL, and Scopus databases to identify relevant studies. A total of 869 articles were identified. Two reviewers screened records independently, finding 25 articles eligible for inclusion. Data extraction was conducted once and validated by the second reviewer. Results: Two of the included studies examined telehealth assessment protocols, whereas the remaining studies focused on the delivery of telehealth interventions. The results of the included studies illustrated both effectiveness and feasibility regarding telehealth for people with poststroke aphasia. However, a lack of procedural variation among the studies was found. Conclusions: Overall, this scoping review yielded continued support for the use of telehealth practices as an alternate mode of delivering both assessment and intervention services to people with poststroke aphasia. However, further research is needed to investigate the range of aphasia assessment and intervention protocols that can be offered via telehealth, such as assessments or interventions that use patient-reported measures or address extralinguistic cognitive abilities.

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