scholarly journals Deep Cerebellar Transcranial Direct Current Stimulation of the Dentate Nucleus to Facilitate Standing Balance in Chronic Stroke Survivors

2019 ◽  
Author(s):  
Zeynab Rezaee ◽  
Surbhi Kaura ◽  
Dhaval Solanki ◽  
Adyasha Dash ◽  
M V Padma Srivastava ◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Lower Limb ◽  
Standing Balance ◽  
Stroke Survivors ◽  
Post Stroke ◽  
Functional Reach

Objective: Cerebrovascular accidents are the second leading cause of death and the third leading cause of disability worldwide. We hypothesized that cerebellar transcranial direct current stimulation (ctDCS) of the dentate nuclei and the lower-limb representations in the cerebellum can improve standing balance functional reach in chronic (> 6 months’ post-stroke) stroke survivors. Materials and Methods: Magnetic resonance imaging(MRI) based subject-specific electric field was computed across 10 stroke survivors and one healthy MRI template to find an optimal bipolar bilateral ctDCS montage to target dentate nuclei and lower-limb representations (lobules VII-IX). Then, in a repeated-measure crossover study on 5 stroke survivors, we compared 15minutes of 2mA ctDCS based on the effects on successful functional reach(%) during standing balance task. Three-way ANOVA investigated the factors of interest– brain regions, montages, stroke participants, and their interactions.Results: “One-size-fits-all” ctDCS montage for the clinical study was found to be bipolar PO9h – PO10h for dentate nuclei and bipolar Exx7–Exx8 for lobules VII-IX with contalesional anode. Bipolar PO9h–PO10h ctDCS performed significantly (alpha=0.05) better in facilitating successful functional reach (%) when compared to bipolar Exx7–Exx8 ctDCS. Furthermore, a linear relationship between successful functional reach (%) and electric field strength was found where bipolar PO9h–PO10h montage resulted in a significantly (alpha=0.05) higher electric field strength when compared to bipolar Exx7–Exx8 montage for the same 2mA current. Conclusion: We presented a rational neuroimaging based approach to optimize deep ctDCS of the dentate nuclei and lower limb representations in the cerebellum for post-stroke balance rehabilitation.

scholarly journals Deep Cerebellar Transcranial Direct Current Stimulation of the Dentate Nucleus to Facilitate Standing Balance in Chronic Stroke Survivors—A Pilot Study

2020 ◽  
Vol 10 (2) ◽  
pp. 94 ◽  
Author(s):  
Zeynab Rezaee ◽  
Surbhi Kaura ◽  
Dhaval Solanki ◽  
Adyasha Dash ◽  
M V Padma Srivastava ◽  
...  
Keyword(s):  
Pilot Study ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Lower Limb ◽  
Standing Balance ◽  
Stroke Survivors ◽  
Functional Reach

Objective: Cerebrovascular accidents are the second leading cause of death and the third leading cause of disability worldwide. We hypothesized that cerebellar transcranial direct current stimulation (ctDCS) of the dentate nuclei and the lower-limb representations in the cerebellum can improve functional reach during standing balance in chronic (>6 months’ post-stroke) stroke survivors. Materials and Methods: Magnetic resonance imaging (MRI) based subject-specific electric field was computed across a convenience sample of 10 male chronic (>6 months) stroke survivors and one healthy MRI template to find an optimal bipolar bilateral ctDCS montage to target dentate nuclei and lower-limb representations (lobules VII–IX). Then, in a repeated-measure crossover study on a subset of 5 stroke survivors, we compared 15 min of 2 mA ctDCS based on the effects on successful functional reach (%) during standing balance task. Three-way ANOVA investigated the factors of interest– brain regions, montages, stroke participants, and their interactions. Results: “One-size-fits-all” bipolar ctDCS montage for the clinical study was found to be PO9h–PO10h for dentate nuclei and Exx7–Exx8 for lobules VII–IX with the contralesional anode. PO9h–PO10h ctDCS performed significantly (alpha = 0.05) better in facilitating successful functional reach (%) when compared to Exx7–Exx8 ctDCS. Furthermore, a linear relationship between successful functional reach (%) and electric field strength was found where PO9h–PO10h montage resulted in a significantly (alpha = 0.05) higher electric field strength when compared to Exx7–Exx8 montage for the same 2 mA current. Conclusion: We presented a rational neuroimaging based approach to optimize deep ctDCS of the dentate nuclei and lower limb representations in the cerebellum for post-stroke balance rehabilitation. However, this promising pilot study was limited by “one-size-fits-all” bipolar ctDCS montage as well as a small sample size.

scholarly journals Investigating the Effects of Cerebellar Transcranial Direct Current Stimulation on Post-Stroke Overground Gait Performance: A Partial Least-Squares Regression Approach

2020 ◽  
Author(s):  
Dhaval Solanki ◽  
Zeynab Rezaee ◽  
Anirban Dutta ◽  
Uttama Lahiri
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Partial Least Squares Regression ◽  
Least Squares Regression ◽  
Significance Level ◽  
Gait Performance ◽  
Post Stroke ◽  
The Mean

Stroke often results in impaired gait, which can limit community ambulation and the quality of life. Recent works have shown the feasibility of transcranial Direct Current Stimulation (tDCS) as an adjuvant treatment to facilitate gait rehabilitation. Since the cerebellum plays an essential role in balance and movement coordination, which is crucial for independent overground ambulation, so, we investigated the effects of cerebellar tDCS (ctDCS) on the post-stroke overground gait performance in chronic stroke survivors. Fourteen chronic post-stroke male subjects were recruited based on convenience sampling at the collaborating hospitals where ten subjects finally participated in the ctDCS study. We evaluated the effects of two ctDCS montages with 2mA direct current, a) optimized configuration for dentate stimulation with 3.14cm2 disc anode at PO10h (10/5 EEG system) and 3.14cm2 disc cathode at PO9h (10/5 EEG system), and b) optimized configuration for leg lobules VII-IX stimulation with 3.14cm2 disc anode at Exx8 (electrodes defined by ROAST) and 3.14cm2 disc cathode at Exx7. We found ctDCS to be acceptable by all the exposed subjects. The ctDCS intervention had an effect on the 'Normalised Step length Affected side' (p=0.1) and 'Gait Stability Ratio' (p=0.0569), which was found using Wilcoxon signed-rank test at 10% significance level. Also, ctDCS montage specific effect was found using a two-sided Wilcoxon rank-sum test at a 5% significance level for 'Step Time Affected Leg' (p=0.0257) and '%Stance Time Unaffected Leg' (p=0.0376). Moreover, the changes in the quantitative gait parameters across both the montages were found to be correlated to the mean electric field strength in the lobules based on partial least squares regression analysis (R2 statistic = 0.6574) where the mean electric field strength at the cerebellar lobules, Vermis VIIIb, Ipsilesional IX, Vermis IX, Ipsilesional X, had the most loading. In conclusion, our feasibility study indicated the potential of a single session of ctDCS to contribute to the immediate improvement in the balance and gait performance in terms of gait-related indices and clinical gait measures.

scholarly journals Comparative Study of AC and Positive and Negative DC Visual Corona for Sphere-Plane Gaps in Atmospheric Air

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2671 ◽  
Author(s):  
Jordi-Roger Riba ◽  
Andrea Morosini ◽  
Francesca Capelli
Keyword(s):  
Experimental Data ◽  
Field Strength ◽  
Electric Field ◽  
Power Systems ◽  
Electric Field Strength ◽  
High Voltage ◽  
Direct Current ◽  
Complex Nature ◽  
High Voltage Direct Current ◽  
Surface Electric Field

Due to the expansion of high-voltage direct current (HVDC) power systems, manufacturers of high-voltage (HV) hardware for alternating current (ac) applications are focusing their efforts towards the HVDC market. Because of the historical preponderance of ac power systems, such manufacturers have a strong background in ac corona but they need to acquire more knowledge about direct current (dc) corona. Due to the complex nature of corona, experimental data is required to describe its behavior. This work performs an experimental comparative analysis between the inception of ac corona and positive and negative dc corona. First, the sphere-plane air gap is analyzed from experimental data, and the corona inception voltages for different geometries are measured in a high-voltage laboratory. Next, the surface electric field strength is determined from finite element method simulations, since it provides valuable information about corona inception conditions. The experimental data obtained are fitted to an equation based on Peek’s law, which allows determining the equivalence between the visual corona surface electric field strength for ac and dc supply. Finally, additional experimental results performed on substation connectors are presented to further validate the previous results by means of commercial high-voltage hardware. The results presented in this paper could be especially valuable for high-voltage hardware manufacturers, since they allow determining the dc voltage and electric field values at which their ac products can withstand free of corona when operating in dc grids.

scholarly journals The effect of cerebellar transcranial direct current stimulation to improve standing balance performance early post-stroke, study protocol of a randomized controlled trial

2019 ◽  
Vol 14 (6) ◽  
pp. 650-657 ◽  
Author(s):  
Sarah B Zandvliet ◽  
Carel GM Meskers ◽  
Rinske HM Nijland ◽  
Andreas Daffertshofer ◽  
Gert Kwakkel ◽  
...  
Keyword(s):  
Randomized Controlled Trial ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Controlled Trial ◽  
Standing Balance ◽  
Balance Performance ◽  
Post Intervention ◽  
Post Stroke ◽  
Randomized Controlled ◽  
Cerebellar Tdcs

Rationale Restoration of adequate standing balance after stroke is of major importance for functional recovery. POstural feedback ThErapy combined with Non-invasive TranscranIAL direct current stimulation (tDCS) in patients with stroke (POTENTIAL) aims to establish if cerebellar tDCS has added value in improving standing balance performance early post-stroke. Methods Forty-six patients with a first-ever ischemic stroke will be enrolled in this double-blind controlled trial within five weeks post-stroke. All patients will receive 15 sessions of virtual reality-based postural feedback training (VR-PFT) in addition to usual care. VR-PFT will be given five days per week for 1 h, starting within five weeks post-stroke. During VR-PFT, 23 patients will receive 25 min of cerebellar anodal tDCS (cb_tDCS), and 23 patients will receive sham stimulation. Study outcome Clinical, posturographic, and neurophysiological measurements will be performed at baseline, directly post-intervention, two weeks post-intervention and at 15 weeks post-stroke. The primary outcome measure will be the Berg Balance Scale (BBS) for which a clinical meaningful difference of six points needs to be established between the intervention and control group at 15 weeks post-stroke. Discussion POTENTIAL will be the first proof-of-concept randomized controlled trial to assess the effects of VR-PFT combined with cerebellar tDCS in terms of standing balance performance in patients early post-stroke. Due to the combined clinical, posturographical and neurophysiological measurements, this trial may give more insights in underlying post-stroke recovery processes and whether these can be influenced by tDCS.

scholarly journals Investigating the Feasibility of Cerebellar Transcranial Direct Current Stimulation to facilitate Post-Stroke Overground Gait Performance in Chronic Stroke: a partial least-squares regression approach

2020 ◽  
Author(s):  
Dhaval Solanki ◽  
Zeynab Rezaee ◽  
Anirban Dutta ◽  
Uttama Lahiri
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Least Squares Regression ◽  
Significance Level ◽  
Gait Performance ◽  
Post Stroke ◽  
Wilcoxon Rank Sum Test ◽  
Gait Parameters ◽  
The Mean

Abstract Background: Cerebellar transcranial Direct Current Stimulation (ctDCS) has been shown to be promising as an adjuvant treatment to facilitate post-stroke gait rehabilitation; however, investigation of lobule-specific electric field effects on overground gait performance has not been performed. Methods: Ten chronic post-stroke male subjects participated in this repeated-measure single-blind crossover study, where we evaluated the single-session effects of two bilateral ctDCS montages that applied 2mA via 3.14cm 2 disc electrodes for 15 minutes targeting a) dentate nuclei (also, anterior and posterior lobes), and b) lower-limb representations (lobules VIIb-IX). A two-sided Wilcoxon rank-sum test was performed at 5% significance level on the percent normalized change measures in the overground gait performance. Partial least squares regression (PLSR) analysis was performed on the quantitative gait parameters as response variables to the mean lobular electric field strength as the predictors. Clinical assessments were performed with the Ten-Meter walk test (TMWT), Timed Up & Go (TUG), and the Berg Balance Scale based on minimal clinically important differences (MCID). Results: The ctDCS montage specific effect was found significant using a two-sided Wilcoxon rank-sum test at a 5% significance level for 'Step Time Affected Leg' (p=0.0257) and '%Stance Time Unaffected Leg' (p=0.0376). The changes in the quantitative gait parameters were found to be correlated to the mean electric field strength in the lobules based on PLSR analysis ( R 2 statistic = 0.6574). Here, the mean electric field strength at the cerebellar lobules, Vermis VIIIb, Ipsi-lesional IX, Vermis IX, Ipsi-lesional X, had the most loading, and were positively related to the 'Step Time Affected Leg' and '%Stance Time Unaffected Leg,' and negatively related to the '%Swing Time Unaffected Leg,' '%Single Support Time Affected Leg.' Clinical assessments found similar improvement in the TMWT (MCID: 0.10m/sec), TUG (MCID: 8sec), and BBS score (MCID: 12.5 points) for both the ctDCS montages. Conclusion: Our feasibility study found an association between the lobular mean electric field strength and the changes in the quantitative gait parameters following a single ctDCS session in chronic stroke. Both the ctDCS montages improved the clinical outcome measures that should be investigated with a larger sample size for clinical validation.

scholarly journals A computational pipeline to determine lobular electric field distribution during cerebellar transcranial direct current stimulation

2019 ◽  
Author(s):  
Zeynab Rezaee ◽  
Anirban Dutta
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Field Distribution ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Electric Field Distribution ◽  
Head Model ◽  
Computational Pipeline ◽  
Model Interaction ◽  
Subject Specific

AbstractObjectiveCerebellar transcranial direct current stimulation (ctDCS) is challenging due to the complexity of the cerebellar structure. Therefore, our objective is to develop a freely available computational pipeline to perform cerebellar atlas-based electric field analysis using magnetic resonance imaging (MRI) guided subject-specific head modeling.MethodsWe present a freely available computational pipeline to determine subject-specific lobular electric field distribution during ctDCS. The computational pipeline can isolate subject-specific cerebellar lobules based on a spatially unbiased atlas (SUIT) for the cerebellum, and then calculates the lobular electric field distribution during ctDCS. The computational pipeline was tested in a case study using a subject-specific head model as well as using a Colin 27 Average Brain. The 5cmx5cm anode was placed 3 cm lateral to inion, and the same sized cathode was placed on the contralateral supraorbital area (called Manto montage) and buccinators muscle (called Celnik montage). A 4×1 HD-ctDCS electrode montage was also implemented for a comparison using analysis of variance (ANOVA).ResultsEta-squared effect size after three-way ANOVA for electric field strength was 0.05 for lobule, 0.00 for montage, 0.04 for head model, 0.01 for lobule*montage interaction, 0.01 for lobule* head model interaction, and 0.00 for montage*head model interaction in case of Enorm. Here, the electric field strength of both the Celnik and the Manto montages affected the lobules Crus II, VIIb, VIII, IX of the targeted cerebellar hemispheres while Manto montage had more bilateral effect. The HD-ctDCS montage primarily affected the lobules Crus I, Crus II, VIIb of the targeted cerebellar hemisphere. Our freely available computational modeling approach to analyze subject-specific lobular electric field distribution during ctDCS provided an insight into healthy human anodal ctDCS results

scholarly journals Investigating the Effects of Cerebellar Transcranial Direct Current Stimulation on Post-Stroke Overground Gait Performance: a partial least-squares regression approach

2020 ◽  
Author(s):  
Dhaval Solanki ◽  
Zeynab Rezaee ◽  
Anirban Dutta ◽  
Uttama Lahiri
Keyword(s):  
Field Strength ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Partial Least Squares Regression ◽  
Least Squares Regression ◽  
Significance Level ◽  
Gait Performance ◽  
Post Stroke ◽  
Wilcoxon Rank Sum Test ◽  
The Mean

Abstract Background Stroke often results in impaired gait, which can limit community ambulation and the quality of life. Recent works have shown the feasibility of transcranial Direct Current Stimulation (tDCS) as an adjuvant treatment to facilitate gait rehabilitation. Since the cerebellum plays an essential role in balance and movement coordination, which is crucial for independent overground ambulation, so, we investigated the effects of cerebellar tDCS (ctDCS) on the post-stroke overground gait performance in chronic stroke survivors. Methods Fourteen chronic post-stroke male subjects were recruited based on convenience sampling at the collaborating hospitals where ten subjects finally participated in the ctDCS gait study. We evaluated the effects of two ctDCS montages with 2 mA direct current, a) optimized configuration for dentate stimulation with 3.14 cm2 disc anode at PO10h (10/5 EEG system) and 3.14 cm2 disc cathode at PO9h (10/5 EEG system), and b) optimized configuration for leg lobules VII-IX stimulation with 3.14 cm2 disc anode at Exx8 (electrodes defined by ROAST) and 3.14 cm2 disc cathode at Exx7. Two-sided Wilcoxon rank-sum test was performed at the 5% significance level on the percent normalized change measures in the overground gait performance. Results We found ctDCS to be acceptable by all the exposed subjects. The ctDCS intervention had an effect on the 'Normalised Step length Affected side' (p = 0.1) and 'Gait Stability Ratio' (p = 0.0569), which was found using Wilcoxon signed-rank test at 10% significance level. Also, ctDCS montage specific effect was found using a two-sided Wilcoxon rank-sum test at a 5% significance level for 'Step Time Affected Leg' (p = 0.0257) and '%Stance Time Unaffected Leg' (p = 0.0376). Moreover, the changes in the quantitative gait parameters across both the montages were found to be correlated to the mean electric field strength in the lobules based on partial least squares regression analysis (R2 statistic = 0.6574) where the mean electric field strength at the cerebellar lobules, Vermis VIIIb, Ipsilesional IX, Vermis IX, Ipsilesional X, had the most loading. Conclusion Our feasibility study indicated the potential of a single session of ctDCS to contribute to the immediate improvement in the balance and gait performance in terms of gait-related indices and clinical gait measures.

Optical Measurement of the Electric Field Strength in a Gel Insulator

2016 ◽  
Vol 136 (10) ◽  
pp. 1420-1421
Author(s):  
Yusuke Tanaka ◽  
Yuji Nagaoka ◽  
Hyeon-Gu Jeon ◽  
Masaharu Fujii ◽  
Haruo Ihori
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Optical Measurement
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