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1.
Intern Emerg Med ; 2024 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-38619714

RESUMEN

Heart failure (HF) is associated with poor outcome after stroke, but data from large prospective trials are sparse.We assessed the impact of HF on clinical endpoints in patients hospitalized with acute ischemic stroke or transient ischemic attack (TIA) enrolled in the prospective, multicenter Systematic Monitoring for Detection of Atrial Fibrillation in Patients with Acute Ischemic Stroke (MonDAFIS) trial. HF was defined as left ventricular ejection fraction (LVEF) < 55% or a history of HF on admission. The composite of recurrent stroke, major bleeding, myocardial infarction, and all-cause death, and its components during the subsequent 24 months were assessed. We used estimated hazard ratios in confounder-adjusted models. Overall, 410/2562 (16.0%) stroke patients fulfilled the HF criteria (i.e. 381 [14.9%] with LVEF < 55% and 29 [1.9%] based on medical history). Patients with HF had more often diabetes, coronary and peripheral arterial disease and presented with more severe strokes on admission. HF at baseline correlated with myocardial infarction (HR 2.21; 95% CI 1.02-4.79), and all-cause death (HR 1.67; 95% CI 1.12-2.50), but not with major bleed (HR 1.93; 95% CI 0.73-5.06) or recurrent stroke/TIA (HR 1.08; 95% CI 0.75-1.57). The data were adjusted for age, stroke severity, cardiovascular risk factors, and randomization. Patients with ischemic stroke or TIA and comorbid HF have a higher risk of myocardial infarction and death compared with non-HF patients whereas the risk of recurrent stroke or major hemorrhage was similar. Trial registration number Clinicaltrials.gov NCT02204267.

2.
Neurol Res Pract ; 5(1): 51, 2023 Oct 05.
Artículo en Inglés | MEDLINE | ID: mdl-37794453

RESUMEN

BACKGROUND: Embolic stroke of undetermined source (ESUS) accounts for a substantial proportion of ischaemic strokes. A stroke recurrence score has been shown to predict the risk of recurrent stroke in patients with ESUS based on a combination of clinical and imaging features. This study aimed to externally validate the performance of the ESUS recurrence score using data from a randomized controlled trial. METHODS: The validation dataset consisted of eligible stroke patients with available magnetic resonance imaging (MRI) data enrolled in the PreDAFIS sub-study of the MonDAFIS study. The score was calculated using three variables: age (1 point per decade after 35 years), presence of white matter hyperintensities (2 points), and multiterritorial ischaemic stroke (3 points). Patients were assigned to risk groups as described in the original publication. The model was evaluated using standard discrimination and calibration methods. RESULTS: Of the 1054 patients, 241 (22.9%) were classified as ESUS. Owing to insufficient MRI quality, three patients were excluded, leaving 238 patients (median age 65.5 years [IQR 20.75], 39% female) for analysis. Of these, 30 (13%) patients experienced recurrent ischaemic stroke or transient ischemic attack (TIA) during a follow-up period of 383 patient-years, corresponding to an incidence rate of 7.8 per 100 patient-years (95% CI 5.3-11.2). Patients with an ESUS recurrence score value of ≥ 7 had a 2.46 (hazard ratio (HR), 95% CI 1.02-5.93) times higher risk of stroke recurrence than patients with a score of 0-4. The cumulative probability of stroke recurrence in the low-(0-4), intermediate-(5-6), and high-risk group (≥ 7) was 9%, 13%, and 23%, respectively (log-rank test, χ2 = 4.2, p = 0.1). CONCLUSIONS: This external validation of a published scoring system supports a threshold of ≥ 7 for identifying ESUS patients at high-risk of stroke recurrence. However, further adjustments may be required to improve the model's performance in independent cohorts. The use of risk scores may be helpful in guiding extended diagnostics and further trials on secondary prevention in patients with ESUS. TRIAL REGISTRATION: Clinical Trials, NCT02204267. Registered 30 July 2014, https://clinicaltrials.gov/ct2/show/NCT02204267 .

3.
Heliyon ; 9(8): e18432, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37534004

RESUMEN

Objective: (1) To assess the accuracy of a standard operating procedure (SOP) regarding the utilization of atrial fibrillation (AF) alarms in everyday clinical practice, and (2) to evaluate the performance of automated continuous surveillance for atrial fibrillation (AF) in hospitalized acute stroke patients. Design: Retrospective cohort study. Setting: Two stroke units from two tertiary care hospitals in Berlin, Germany. Participants: We identified 635 patients with ischemic stroke diagnosis for the time period between 01. January and 30. September 2021 of which 176 patients had recorded AF alarms during monitoring. Of those, 115 patients were randomly selected for evaluation. After excluding 6 patients with hemorrhagic stroke in their records, 109 patients (mean age: 79.1 years, median NIHSS at admission: 6, 57% female) remained for analysis. Intervention: Using a clinical data warehouse for comprehensive data storage we retrospectively downloaded and visualized ECG data segments of 65 s duration around the automated AF alarms. We restricted the maximum number of ECG segments to ten per patient. Each ECG segment plot was uploaded into a REDCap database and categorized as either AF, non-AF or artifact by manual review. Atrial flutter was subsumed as AF. These classifications were then matched with 1) medical history and known diseases before stroke, 2) discharge diagnosis, and 3) recommended treatment plan in the medical history using electronic health records. Main outcome measures: The primary outcome was the proportion of previously unknown AF diagnoses correctly identified by the monitoring system but missed by the clinical team during hospitalization. Secondary outcomes included the proportion of patients in whom a diagnosis of AF would likely have led to anticoagulant therapy. We also evaluated the accuracy of the automated detection system in terms of its positive predictive value (PPV). Results: We evaluated a total of 717 ECG alarm segments from 109 patients. In 4 patients (3.7, 95% confidence interval [CI] 1.18-9.68%) physicians had missed AF despite at least one true positive alarm. All four patients did not receive long-term secondary prevention in form of anticoagulant therapy. 427 out of 717 alarms were rated true positives, resulting in a positive predictive value of 0.6 (CI 0.56-0.63) in this cohort. Conclusion: By connecting a data warehouse, electronic health records and a REDCap survey tool, we introduce a path to assess the monitoring quality of AF in acute stroke patients. We find that implemented standards of procedure to detect AF during stroke unit care are effective but leave room for improvement. Such data warehouse-based concepts may help to adjust internal processes or identify targets of further investigations.

4.
Neurol Res Pract ; 5(1): 21, 2023 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-37259147

RESUMEN

BACKGROUND: About 25% of all ischaemic strokes are related to cardio-embolism, most often due to atrial fibrillation (AF). Little is known about the extent and standardization of routine cardiac diagnostic work-up at certified stroke-units in Germany. METHODS: The MonDAFIS study included non-AF patients with acute ischaemic stroke or transient ischaemic attack (TIA) at 38 certified stroke-units in Germany. Here, we analysed routine diagnostic work-up and disregarded study-related Holter-ECG monitoring. We compared duration of stroke-unit stay, number of 24-h Holter-ECGs, and echocardiography performed between university-based comprehensive stroke centres (UCSC, 12 hospitals, 1606 patients), non university-based comprehensive stroke centres (nUCSC, 14 hospitals, 892 patients), and primary stroke centres at non-university hospitals (PCS, 12 hospitals, 933 patients) using multivariable mixed regression analyses. Detection of a first AF episode in-hospital was also compared between hospitals of different stroke-unit levels. RESULTS: In 3431 study patients (mean age 66.2 years, 39.5% female, median NIHSS = 2 on admission), median duration of the stroke-unit stay was 72 h (IQR 42-86). Stroke-unit stay was longer (categorised ≤ 24/ > 24- ≤ 72/ > 72 h) for patients with severe stroke (NIHSS score ≥ 5/ < 5: OR = 1.6, 95%CI 1.3-2.0) and for patients with ischaemic stroke vs. TIA (OR = 1.7, 95%CI 1.4-2.1). Overall, 2149/3396 (63.3%) patients underwent at least one additional 24-h Holter-ECG (median 1 [IQR 0-1], range 0-7). Holter-ECG rate was 47% in UCSC, 71% in nUCSC, and 84% in PCS. Compared to PCS, AF was less often detected in-hospital in UCSC (OR = 0.65, 95%CI 0.45-0.93) and nUCSC (OR = 0.69, 95%CI 0.46-1.04). Transoesophageal echocardiography (TEE) only was performed in 513/3391 (15.1%) study patients, transthoracic echocardiography (TTE) only in 1228/3391 (36.2%), and TEE combined with TTE in 1020/3391 (30.1%) patients. Patients younger than 60 years (vs. ≥ 60 years) underwent TEE more often than those older than 60 years (OR = 3.44, 95%CI 2.67-4.42). TEE (IQR 34-65%) and TTE rate (IQR 40-85%) varied substantially among study centres. Echocardiography rate (TTE and/or TEE) was 74.0% in UCSC, 85.4% in nUCSC, and 90.3% in PSC, respectively. CONCLUSIONS: In the MonDAFIS study, the routine use of echocardiography and Holter-ECG monitoring varied in participating stroke centres and at stroke-unit level, if grouped according to stroke-unit certification grade and hospitals´ university status. Trial registration Clinical Trials, NCT02204267. Registered 30 July 2014, https://clinicaltrials.gov/ct2/show/NCT02204267 .

5.
J Am Heart Assoc ; 12(2): e027149, 2023 01 17.
Artículo en Inglés | MEDLINE | ID: mdl-36628982

RESUMEN

Background In patients with acute ischemic stroke, little is known regarding the frequency of abnormal ECG findings other than atrial fibrillation and their association with cardiovascular outcomes. We aim to analyze the frequency and type of abnormal ECG findings, subsequent changes in medical treatment, and their association with cardiovascular outcomes in patients with acute ischemic stroke. Methods and Results In the investigator-initiated multicenter MonDAFIS (impact of standardized monitoring for detection of atrial fibrillation in ischemic stroke) study, 3465 patients with acute ischemic stroke or transient ischemic attack and without known atrial fibrillation were randomized 1:1 to receive Holter-ECG for up to 7 days in-hospital with systematic evaluation in a core cardiology laboratory (intervention group) or standard diagnostic care (control group). Outcomes included predefined abnormal ECG findings (eg, pauses, atrial fibrillation, brady-/tachycardias), medical management in the intervention group, and combined vascular end point (recurrent stroke, myocardial infarction, major bleeds, or all-cause death) and mortality at 24 months in both randomization groups. Predefined abnormal ECG findings were detected in 326 of 1693 (19.3%) patients in the intervention group. Twenty of these 326 patients (6.1%) received a pacemaker, and 62 of 326 (19.0%) patients had newly initiated or discontinued ß-blocker medication. Discontinuation of ß-blockers was associated with a higher death rate in the control group than in the intervention group during 24 months after enrollment (adjusted hazard ratio, 11.0 [95% CI, 2.4-50.4]; P=0.025 for interaction). Conclusions Systematic in-hospital Holter ECG reveals abnormal findings in 1 of 5 patients with acute stroke, and mortality was lower at 24 months in patients with systematic ECG recording in the hospital. Further studies are needed to determine the potential impact of medical management of abnormal ECG findings. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02204267.


Asunto(s)
Fibrilación Atrial , Ataque Isquémico Transitorio , Accidente Cerebrovascular Isquémico , Accidente Cerebrovascular , Humanos , Ataque Isquémico Transitorio/diagnóstico , Ataque Isquémico Transitorio/terapia , Ataque Isquémico Transitorio/etiología , Fibrilación Atrial/complicaciones , Fibrilación Atrial/diagnóstico , Accidente Cerebrovascular Isquémico/complicaciones , Accidente Cerebrovascular/etiología , Electrocardiografía Ambulatoria
6.
Eur Stroke J ; 7(3): 230-237, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-36082264

RESUMEN

Paroxysmal Atrial fibrillation (AF) is often clinically silent and may be missed by the usual diagnostic workup after ischemic stroke. We aimed to determine whether shape characteristics of ischemic stroke lesions can be used to predict AF in stroke patients without known AF at baseline. Lesion shape quantification on brain MRI was performed in selected patients from the intervention arm of the Impact of standardized MONitoring for Detection of Atrial Fibrillation in Ischemic Stroke (MonDAFIS) study, which included patients with ischemic stroke or TIA without prior AF. Multiple morphologic parameters were calculated based on lesion segmentation in acute brain MRI data. Multivariate logistic models were used to test the association of lesion morphology, clinical parameters, and AF. A stepwise elimination regression was conducted to identify the most important variables. A total of 755 patients were included. Patients with AF detected within 2 years after stroke (n = 86) had a larger overall oriented bounding box (OBB) volume (p = 0.003) and a higher number of brain lesion components (p = 0.008) than patients without AF. In the multivariate model, OBB volume (OR 1.72, 95%CI 1.29-2.35, p < 0.001), age (OR 2.13, 95%CI 1.52-3.06, p < 0.001), and female sex (OR 2.45, 95%CI 1.41-4.31, p = 0.002) were independently associated with detected AF. Ischemic lesions in patients with detected AF after stroke presented with a more dispersed infarct pattern and a higher number of lesion components. Together with clinical characteristics, these lesion shape characteristics may help in guiding prolonged cardiac monitoring after stroke.

7.
Eur J Neurol ; 29(9): 2716-2724, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35652747

RESUMEN

BACKGROUND AND PURPOSE: Impaired kidney function is associated with an increased risk of vascular events in acute stroke patients, when assessed by single measurements of estimated glomerular filtration rate (eGFR). It is unknown whether repeated measurements provide additional information for risk prediction. METHODS: The MonDAFIS (Systematic Monitoring for Detection of Atrial Fibrillation in Patients with Acute Ischemic Stroke) study randomly assigned 3465 acute ischemic stroke patients to either standard procedures or an additive Holter electrocardiogram. Baseline eGFR (CKD-EPI formula) were dichotomized into values of < versus ≥60 ml/min/1.73 m2 . eGFR dynamics were classified based on two in-hospital values as "stable normal" (≥60 ml/min/1.73 m2 ), "increasing" (by at least 15% from baseline, second value ≥ 60 ml/min/1.73 m2 ), "decreasing" (by at least 15% from baseline of ≥60 ml/min/1.73 m2 ), and "stable decreased" (<60 ml/min/1.73 m2 ). The composite endpoint (stroke, major bleeding, myocardial infarction, all-cause death) was assessed after 24 months. We estimated hazard ratios in confounder-adjusted models. RESULTS: Estimated glomerular filtration rate at baseline was available in 2947 and a second value in 1623 patients. After adjusting for age, stroke severity, cardiovascular risk factors, and randomization, eGFR < 60 ml/min/1.73 m2 at baseline (hazard ratio [HR] = 2.2, 95% confidence interval [CI] = 1.40-3.54) as well as decreasing (HR = 1.79, 95% CI = 1.07-2.99) and stable decreased eGFR (HR = 1.64, 95% CI = 1.20-2.24) were independently associated with the composite endpoint. In addition, eGFR < 60 ml/min/1.732 at baseline (HR = 3.02, 95% CI = 1.51-6.10) and decreasing eGFR were associated with all-cause death (HR = 3.12, 95% CI = 1.63-5.98). CONCLUSIONS: In addition to patients with low eGFR levels at baseline, also those with decreasing eGFR have increased risk for vascular events and death; hence, repeated estimates of eGFR might add relevant information to risk prediction.


Asunto(s)
Fibrilación Atrial , Ataque Isquémico Transitorio , Accidente Cerebrovascular Isquémico , Accidente Cerebrovascular , Fibrilación Atrial/complicaciones , Tasa de Filtración Glomerular , Humanos , Ataque Isquémico Transitorio/complicaciones , Factores de Riesgo , Accidente Cerebrovascular/complicaciones
8.
Lancet Neurol ; 20(6): 426-436, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-34022169

RESUMEN

BACKGROUND: Systematic electrocardiogram (ECG) monitoring improves detection of covert atrial fibrillation in stroke survivors but the effect on secondary prevention is unknown. We aimed to assess the effect of systematic ECG monitoring of patients in hospital on the rate of oral anticoagulant use after 12 months. METHODS: In this investigator-initiated, randomised, open-label, parallel-group multicentre study with masked endpoint adjudication, we recruited patients aged at least 18 years with acute ischaemic stroke or transient ischaemic attack without known atrial fibrillation in 38 certified stroke units in Germany. Patients were randomly assigned (1:1) to usual diagnostic procedures for atrial fibrillation detection (control group) or additional Holter-ECG recording for up to 7 days in hospital (intervention group). Patients were stratified by centre using a random permuted block design. The primary outcome was the proportion of patients on oral anticoagulants at 12 months after the index event in the intention-to-treat population. Secondary outcomes included the number of patients with newly diagnosed atrial fibrillation in hospital and the composite of recurrent stroke, major bleeding, myocardial infarction, or death after 6 months, 12 months, and 24 months. This trial was registered with ClinicalTrials.gov, NCT02204267, and is completed and closed for participants. FINDINGS: Between Dec 9, 2014, and Sept 11, 2017, 3465 patients were randomly assigned, 1735 (50·1%) to the intervention group and 1730 (49·9%) to the control group. Oral anticoagulation status was available in 2920 (84·3%) patients at 12 months (1484 [50·8%] in the intervention group and 1436 [49·2%] in the control group). For the primary outcome, at 12 months, 203 (13·7%) of 1484 patients in the intervention group versus 169 (11·8%) of 1436 in the control group were on oral anticoagulants (odds ratio [OR] 1·2 [95% CI 0·9-1·5]; p=0·13). Atrial fibrillation was newly detected in patients in hospital in 97 (5·8%) of 1714 in the intervention group versus 68 (4·0%) of 1717 in the control group (hazard ratio [HR] 1·4 [95% CI 1·0-2·0]; p=0·024). The composite of cardiovascular outcomes and death did not differ between patients randomly assigned to the intervention group versus the control group at 24 months (232 [13·5%] of 1714 vs 249 [14·5%] of 1717; HR 0·9 [0·8-1·1]; p=0·43). Skin reactions due to study ECG electrodes were reported in 56 (3·3%) patients in the intervention group. All-cause death occured in 73 (4·3%) patients in the intervention group and in 103 (6·0%) patients in the control group (OR 0·7 [0·5-0·9]). INTERPRETATION: Systematic core centrally reviewed ECG monitoring is feasible and increases the detection rate of atrial fibrillation in unselected patients hospitalised with acute ischaemic stroke or transient ischaemic attack, if added to usual diagnostic care in certified German stroke units. However, we found no effect of systematic ECG monitoring on the rate of oral anticoagulant use after 12 months and further efforts are needed to improve secondary stroke prevention. FUNDING: Bayer Vital. TRANSLATION: For the German translation of the abstract see Supplementary Materials section.


Asunto(s)
Fibrilación Atrial/fisiopatología , Isquemia Encefálica/fisiopatología , Accidente Cerebrovascular Isquémico/fisiopatología , Monitoreo Fisiológico/métodos , Anciano , Anciano de 80 o más Años , Fibrilación Atrial/diagnóstico , Fibrilación Atrial/epidemiología , Isquemia Encefálica/diagnóstico , Isquemia Encefálica/epidemiología , Electrocardiografía/métodos , Femenino , Humanos , Accidente Cerebrovascular Isquémico/diagnóstico , Accidente Cerebrovascular Isquémico/epidemiología , Masculino , Persona de Mediana Edad , Factores de Riesgo
9.
Arch Cardiovasc Dis ; 111(4): 246-256, 2018 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29113786

RESUMEN

BACKGROUND: Pulmonary dysfunction and cardiovascular disease are major causes of impaired health status in later life, and co-development of these diseases has been reported. AIM: To better understand the pathobiology involved in the co-development of these diseases. METHODS: We investigated the impact of pulmonary dysfunction on the development of cardiovascular disease among people aged≥50 years in the English longitudinal study of ageing (ELSA). Hazard ratios were estimated by Cox proportional hazards regression models, with and without a time-dependent update of exposure and confounders. Pulmonary function was divided into three categories, with the least affected category as the reference. RESULTS: People with pulmonary dysfunction were at higher risk of developing cardiovascular disease than those with normal pulmonary function: the hazard ratio for pulmonary dysfunction versus healthy in the time-dependent crude analysis of model 1, adjusted for age, body mass index, sex, angina pectoris and heart arrhythmia, was 1.49 (95% confidence interval 1.2-1.9). The effect varied with the precise definition of pulmonary dysfunction and the subtype of the cardiovascular disease, and decreased after correction for some additional confounders but not after correction for inflammatory biomarkers. CONCLUSIONS: A history of pulmonary disease increased the risk of developing cardiovascular disease, but inflammation did not seem to alter the effect of pulmonary dysfunction on cardiovascular disease development. This insight may lead to better understanding and treatment of cardiovascular comorbidities in pulmonary disease; it also indicates that the potentially beneficial effect of targeted anti-inflammatory drugs for pulmonary disease, in terms of reducing cardiovascular risk in these patients, may be limited.


Asunto(s)
Enfermedades Cardiovasculares/epidemiología , Enfermedades Pulmonares/epidemiología , Pulmón/fisiopatología , Factores de Edad , Anciano , Biomarcadores/sangre , Enfermedades Cardiovasculares/diagnóstico , Enfermedades Cardiovasculares/fisiopatología , Comorbilidad , Inglaterra/epidemiología , Femenino , Volumen Espiratorio Forzado , Humanos , Incidencia , Mediadores de Inflamación/sangre , Estimación de Kaplan-Meier , Estudios Longitudinales , Enfermedades Pulmonares/diagnóstico , Enfermedades Pulmonares/fisiopatología , Masculino , Persona de Mediana Edad , Pronóstico , Modelos de Riesgos Proporcionales , Factores de Riesgo , Factores de Tiempo , Capacidad Vital
10.
Front Cell Neurosci ; 11: 238, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28860969

RESUMEN

Understanding processes performed by an intact visual cortex as the basis for developing methods that enhance or restore visual perception is of great interest to both researchers and medical practitioners. Here, we explore whether contrast sensitivity, a main function of the primary visual cortex (V1), can be improved in healthy subjects by repetitive, noninvasive anodal transcranial direct current stimulation (tDCS). Contrast perception was measured via threshold perimetry directly before and after intervention (tDCS or sham stimulation) on each day over 5 consecutive days (24 subjects, double-blind study). tDCS improved contrast sensitivity from the second day onwards, with significant effects lasting 24 h. After the last stimulation on day 5, the anodal group showed a significantly greater improvement in contrast perception than the sham group (23 vs. 5%). We found significant long-term effects in only the central 2-4° of the visual field 4 weeks after the last stimulation. We suspect a combination of two factors contributes to these lasting effects. First, the V1 area that represents the central retina was located closer to the polarization electrode, resulting in higher current density. Second, the central visual field is represented by a larger cortical area relative to the peripheral visual field (cortical magnification). This is the first study showing that tDCS over V1 enhances contrast perception in healthy subjects for several weeks. This study contributes to the investigation of the causal relationship between the external modulation of neuronal membrane potential and behavior (in our case, visual perception). Because the vast majority of human studies only show temporary effects after single tDCS sessions targeting the visual system, our study underpins the potential for lasting effects of repetitive tDCS-induced modulation of neuronal excitability.

11.
Front Hum Neurosci ; 9: 236, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25972805

RESUMEN

Chronic communication impairment is common after stroke, and conventional speech and language therapy (SLT) strategies have limited effectiveness in post-stroke aphasia. Neurorehabilitation with non-invasive brain stimulation techniques (NIBS)-particularly repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS)-may enhance the effects of SLT in selected patients. Applying inhibitory NIBS to specific homologous language regions may induce neural reorganization and reduce interhemispheric competition. This mini review highlights randomized controlled trials (RCTs) and randomized cross-over trials using low-frequency rTMS or cathodal tDCS over the non-lesioned non-language dominant hemisphere and performs an exploratory meta-analysis of those trials considered combinable. Using a random-effects model, a meta-analysis of nine eligible trials involving 215 participants showed a significant mean effect size of 0.51 (95% CI = 0.24-0.79) for the main outcome "accuracy of naming" in language assessment. No heterogeneity was observed (I (2) = 0%). More multicenter RCTs with larger populations and homogenous intervention protocols are required to confirm these and the longer-term effects.

12.
Restor Neurol Neurosci ; 29(6): 453-61, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-22278016

RESUMEN

PURPOSE: TDCS can increase excitability in the visual cortex. It is a matter of current debate if tDCS can improve visual performance. Promising parameters to measure detection sensitivity may be those of the signal detection theory ( = SDT), as it allows differentiating between response bias and detection sensitivity changes. The measure of detection sensitivity can be used to predict actual performance under a wide variety of different response criteria. METHODS: Here we test if the SDT can quantify tDCS-induced effects in a visual contrast discrimination task in healthy subjects. RESULTS: Anodal stimulation of the visual cortex improved performance, as calculated by detection sensitivity for stimuli presented in the center of the visual field. More peripheral locations in the visual field were unaffected by anodal stimulation. Cathodal stimulation and sham stimulation of the visual cortex had no consistent effect on detection sensitivity. The response bias was not affected by any type of stimulation. CONCLUSIONS: Neuroplastic changes in the visual cortex induced by anodal tDCS can be measured by SDT, suggesting SDT could prospectively be a useful approach for monitoring restorative tDCS-effects on visual function in patients with central visual deficits.


Asunto(s)
Mapeo Encefálico , Detección de Señal Psicológica , Corteza Visual/fisiología , Adulto , Análisis de Varianza , Electrodos , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Estimulación Luminosa , Psicofísica , Tiempo de Reacción/fisiología , Estimulación Magnética Transcraneal/métodos , Adulto Joven
13.
Exp Brain Res ; 207(3-4): 283-90, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21046369

RESUMEN

In this study, we aimed to characterize the effect of anodal and cathodal direct current stimulation (tDCS) on contrast sensitivity inside the central 10 degrees of the visual field in healthy subjects. Distinct eccentricities were investigated separately, since at the cortical level, more central regions of the visual field are represented closer to the occipital pole, i.e. closer to the polarizing electrodes, than are the more peripheral regions. Using a double-blind and sham-controlled within-subject design, we measured the effect of stimulation and potential learning effect separately across testing days. Anodal stimulation of the visual cortex compared to sham stimulation yielded a significant increase in contrast sensitivity within 8° of the visual field. A significant increase in contrast sensitivity between the conditions "pre" and "post" anodal stimulation was only obtained for the central positions at eccentricities smaller than 2°. Cathodal stimulation of the visual cortex did not affect contrast sensitivity at either eccentricity. Perceptual learning across testing days was only observed for threshold perimetry before stimulation. Measuring contrast sensitivity changes after tDCS with a standard clinical tool such as threshold perimetry may provide an interesting perspective in assessing therapeutic effects of tDCS in ophthalmological or neurological defects (e.g. with foveal sparing vs. foveal splitting).


Asunto(s)
Sensibilidad de Contraste/fisiología , Terapia por Estimulación Eléctrica/métodos , Aprendizaje/fisiología , Corteza Visual/fisiología , Adulto , Método Doble Ciego , Femenino , Humanos , Masculino
14.
PLoS One ; 3(9): e3167, 2008 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-18779857

RESUMEN

To what extent are the left and right visual hemifields spatially coded in the dorsal frontoparietal attention network? In many experiments with neglect patients, the left hemisphere shows a contralateral hemifield preference, whereas the right hemisphere represents both hemifields. This pattern of spatial coding is often used to explain the right-hemispheric dominance of lesions causing hemispatial neglect. However, pathophysiological mechanisms of hemispatial neglect are controversial because recent experiments on healthy subjects produced conflicting results regarding the spatial coding of visual hemifields. We used an fMRI paradigm that allowed us to distinguish two attentional subprocesses during a visual search task. Either within the left or right hemifield subjects first attended to stationary locations (spatial orienting) and then shifted their attentional focus to search for a target line. Dynamic changes in spatial coding of the left and right hemifields were observed within subregions of the dorsal front-parietal network: During stationary spatial orienting, we found the well-known spatial pattern described above, with a bilateral hemifield representation in the right hemisphere and a contralateral preference in the left hemisphere. However, during search, the right hemisphere had a contralateral preference and the left hemisphere equally represented both hemifields. This finding leads to novel perspectives regarding models of visuospatial attention and hemispatial neglect.


Asunto(s)
Lóbulo Frontal/fisiología , Lóbulo Parietal/fisiología , Percepción Espacial/fisiología , Percepción Visual/fisiología , Adulto , Conducta , Percepción de Forma , Lateralidad Funcional/fisiología , Humanos , Imagen por Resonancia Magnética/métodos , Memoria , Orientación/fisiología , Reconocimiento Visual de Modelos/fisiología , Proyectos de Investigación
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