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Neuroprotection by Transcranial Direct Current Stimulation in Rodent Models of Focal Ischemic Stroke: A Meta-Analysis.

ABSTRACT: Infarct size is associated with stroke severity in clinical studies, so reducing it has become an important target and research hotspot in the treatment of ischemic stroke. Some preclinical studies have shown transcranial direct current stimulation (tDCS) reduced infarct size and improved neurological deficit, but others have not found beneficial effects. Besides, the optimal pattern of tDCS for ischemic stroke remains largely unknown. To shed light on the current circumstance and future research directions, the systematic review evaluated the effect of different tDCS paradigms in reducing infarct size and improving neurological deficit in rodent models of ischemic stroke and assessed the methodological quality of current literature. We searched the MEDLINE (via PubMed), EMBASE, Web of Science, and Scopus from their inception to August 18, 2021, to identify studies evaluating the effects of tDCS in rodent models of ischemic stroke. Eight studies were included, of which seven studies were included in the meta-analysis. The results showed cathodal tDCS, rather than anodal tDCS, reduced infarct size mainly measured by tetrazolium chloride and magnetic resonance imaging (standardized mean difference: -1.13; 95% CI: -1.72, -0.53; p = 0.0002) and improved neurological deficit assessed by a modified neurological severity score (standardized mean difference: -2.10; 95% CI: -3.78, -0.42; p = 0.01) in an early stage of focal ischemic stroke in rodent models. Subgroup analyses showed effects of cathodal tDCS on infarct size were not varied by ischemia duration (ischemia for 1, 1.5, and 2 h or permanent ischemia) and anesthesia (involving isoflurane and ketamine). The overall quality of studies included was low, thus the results must be interpreted cautiously. Published studies suggest that cathodal tDCS may be a promising avenue to explore for augmenting rehabilitation from focal ischemic stroke. Considering the methodological limitations, it is unreliable to blindly extrapolate the animal data to the clinical practice. Future research is needed to investigate the mechanism of tDCS in a randomized and blinded fashion in clinically relevant stroke models, such as elderly animals, female animals, and animals with comorbidities, to find an optimal treatment protocol.

SUBMITTER: Huang J

PROVIDER: S-EPMC8649802 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundTranscranial direct current stimulation (tDCS) has been investigated mainly in adults and doses may not be appropriate in pediatric applications. In perinatal stroke where potential applications are promising, rational adaptation of dosage for children remains under investigation.ObjectiveConstruct child-specific tDCS dosing parameters through case study within a perinatal stroke tDCS safety and feasibility trial.Methods10-year-old subject with a diagnosis of presumed perinatal ischemic stroke and hemiparesis was identified. T1 magnetic resonance imaging (MRI) scans used to derive computerized model for current flow and electrode positions. Workflow using modeling results and consideration of dosage in previous clinical trials was incorporated. Prior ad hoc adult montages vs. de novo optimized montages provided distinct risk benefit analysis. Approximating adult dose required consideration of changes in both peak brain current flow and distribution which further tradeoff between maximizing efficacy and adding safety factors. Electrode size, position, current intensity, compliance voltage, and duration were controlled independently in this process.ResultsBrain electric fields modeled and compared to values previously predicted models (Datta et al., 2011; Minhas et al., 2012). Approximating conservative brain current flow patterns and intensities used in previous adult trials for comparable indications, the optimal current intensity established was 0.7 mA for 10 min with a tDCS C3/C4 montage. Specifically 0.7 mA produced comparable peak brain current intensity of an average adult receiving 1.0 mA. Electrode size of 5 × 7 cm(2) with 1.0 mA and low-voltage tDCS was employed to maximize tolerability. Safety and feasibility confirmed with subject tolerating the session well and no serious adverse events.ConclusionRational approaches to dose customization, with steps informed by computational modeling, may improve guidance for pediatric stroke tDCS trials.

Project description:Importance:Aphasia is a debilitating language disorder for which behavioral speech therapy is the most efficient treatment, but therapy outcomes are variable and full recovery is not always achieved. It remains unclear if adjunctive brain stimulation (anodal transcranial direct current stimulation [A-tDCS]) applied during aphasia therapy can improve outcomes. Objective:To examine the futility of studying A-tDCS as an adjunctive intervention during speech therapy to improve speech production (naming) for individuals with long-term poststroke aphasia. Design, Setting, and Participants:Double-blinded, prospective randomized clinical trial using a futility design to test adjunctive A-tDCS during speech therapy. The setting was an outpatient clinic. Enrollment of individuals began in August 2012 and was completed in March 2017, and the duration of follow-up was 6 months. Analyses began in April 2017. The study recruited from a volunteer sample, and 89 patients were screened. Patients with long-term (>6 months) aphasia due to 1 previous left hemisphere stroke were enrolled. In comparing A-tDCS and sham tDCS, patients were matched based on site (University of South Carolina or Medical University of South Carolina), baseline age, type of aphasia, and aphasia severity. Interventions:Outpatient speech therapy for 3 weeks (15 sessions, 45 minutes each) combined with either A-tDCS vs sham tDCS applied to preserved left temporal lobe regions. Main Outcomes and Measures:The primary outcome was the ability to name common objects, assessed twice before and after therapy. Results:A total of 74 patients were enrolled. Participants had a mean (SD) age of 60 (10) years, had 15 (2) years of education, and were 44 (40) months from stroke onset. There were 52 men (70%) and 62 non-Hispanic white individuals (84%). Most were retired or not employed (59 [80%]). Broca aphasia was the most common aphasia type (39 [52.7%]). The adjusted mean (SE) change from pretreatment baseline in correct naming was 13.9 (2.4) words (95% CI, 9.0-18.7) for A-tDCS and 8.2 (2.2) words (95% CI, 3.8-12.6) for sham tDCS, with mean (SE) A-tDCS difference of 5.7 (3.3) words (95% CI, -0.9 to 12.3), indicating a relative 70% increase in correct naming for A-tDCS relative to sham. The futility hypothesis P value was .90, indicating failure to reject the null hypothesis and, therefore, providing no evidence that further study of A-tDCS is futile. No serious adverse events were associated with A-tDCS. Conclusions and Relevance:Our findings provide motivation to proceed with another trial to study the effect of A-tDCS on the outcome of aphasia treatment in individuals poststroke. Anodal tDCS during speech therapy is feasible and potentially transformative for aphasia treatment and should be further studied. Trial Registration:ClinicalTrials.gov Identifier: NCT01686373.

Project description:Introduction: Conventional transcranial direct current stimulation (tDCS) and high-definition tDCS (HD-tDCS) may improve motor learning in children. Mechanisms are not understood. Neuronavigated robotic transcranial magnetic stimulation (TMS) can produce individualised maps of primary motor cortex (M1) topography. We aimed to determine the effects of tDCS- and HD-tDCS-enhanced motor learning on motor maps. Methods: Typically developing children aged 12-18 years were randomised to right M1 anodal tDCS, HD-tDCS, or Sham during training of their left-hand on the Purdue Pegboard Task (PPT) over 5 days. Bilateral motor mapping was performed at baseline (pre), day 5 (post), and 6-weeks retention time (RT). Primary muscle was the first dorsal interosseous (FDI) with secondary muscles of abductor pollicis brevis (APB) and adductor digiti minimi (ADM). Primary mapping outcomes were volume (mm2/mV) and area (mm2). Secondary outcomes were centre of gravity (COG, mm) and hotspot magnitude (mV). Linear mixed-effects modelling was employed to investigate effects of time and stimulation type (tDCS, HD-tDCS, Sham) on motor map characteristics. Results: Twenty-four right-handed participants (median age 15.5 years, 52% female) completed the study with no serious adverse events or dropouts. Quality maps could not be obtained in two participants. No effect of time or group were observed on map area or volume. LFDI COG (mm) differed in the medial-lateral plane (x-axis) between tDCS and Sham (p = 0.038) from pre-to-post mapping sessions. Shifts in map COG were also observed for secondary left-hand muscles. Map metrics did not correlate with behavioural changes. Conclusion: Robotic TMS mapping can safely assess motor cortex neurophysiology in children undergoing motor learning and neuromodulation interventions. Large effects on map area and volume were not observed while changes in COG may occur. Larger controlled studies are required to understand the role of motor maps in interventional neuroplasticity in children.

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Neuroprotection by Transcranial Direct Current Stimulation in Rodent Models of Focal Ischemic Stroke: A Meta-Analysis.

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