Chronic Covert Brain Infarctions and White Matter Hyperintensities in Patients With Stroke, Transient Ischemic Attack, and Stroke Mimic

Association of covert brain infarct phenotype with stroke recurrence in first-ever manifest ischemic stroke according to etiology

INTRODUCTION

Covert brain infarcts (CBI) are frequent incidental findings on MRI and associated with future stroke risk in patients without a history of clinically evident cerebrovascular events. However, the prognostic value of CBI in first-ever ischemic stroke patients is unclear and previous studies did not report on different etiological stroke subtypes. We aimed to test CBI phenotypes and their association with stroke recurrence in first-ever ischemic stroke patients according to stroke etiology.

PATIENTS AND METHODS

This study is a pooled data analysis of two prospectively collected cohorts of consecutive first-ever ischemic stroke patients admitted to the comprehensive stroke centers of Bern (Switzerland) and Graz (Austria). CBI phenotypes were identified on brain MRI within 72 h after admission. All patients underwent a routine follow-up (median: 12 months) to identify stroke recurrence.

RESULTS

Of 1577 consecutive ischemic stroke patients (median age: 71 years), 691 patients showed CBI on brain MRI (44%) and 88 patients had a recurrent ischemic stroke (6%). Baseline CBI were associated with stroke recurrence in multivariable analysis (HR 1.9, 95% CI 1.1-3.3). CBI phenotypes with the highest risk for stroke recurrence were cavitatory CBI in small vessel disease (SVD)-related stroke (HR 7.1, 95% CI 1.6-12.6) and cortical CBI in patients with atrial fibrillation (HR 3.0, 95% CI 1.1-8.1).

DISCUSSION AND CONCLUSION

This study reports a ≈ 2-fold increased risk for stroke recurrence in first-ever ischemic stroke patients with CBI. The risk of recurrent stroke was highest in patients with cavitatory CBI in SVD-related stroke and cortical CBI in patients with atrial fibrillation.Subject terms: Covert brain infarcts, stroke.

Characterizing upper extremity fine motor function in the presence of white matter hyperintensities: A 7 T MRI cross-sectional study in older adults

BACKGROUND

White matter hyperintensities (WMH) are a prevalent radiographic finding in the aging brain studies. Research on WMH association with motor impairment is mostly focused on the lower-extremity function and further investigation on the upper-extremity is needed. How different degrees of WMH burden impact the network of activation recruited during upper limb motor performance could provide further insight on the complex mechanisms of WMH pathophysiology and its interaction with aging and neurological disease processes.

METHODS

40 healthy elderly subjects without a neurological/psychiatric diagnosis were included in the study (16F, mean age 69.3 years). All subjects underwent ultra-high field 7 T MRI including structural and finger tapping task-fMRI. First, we quantified the WMH lesion load and its spatial distribution. Secondly, we performed a data-driven stratification of the subjects according to their periventricular and deep WMH burdens. Thirdly, we investigated the distribution of neural recruitment and the corresponding activity assessed through BOLD signal changes among different brain regions for groups of subjects. We clustered the degree of WMH based on location, numbers, and volume into three categories; ranging from mild, moderate, and severe. Finally, we explored how the spatial distribution of WMH, and activity elicited during task-fMRI relate to motor function, measured with the 9-Hole Peg Test.

RESULTS

Within our population, we found three subgroups of subjects, partitioned according to their periventricular and deep WMH lesion load. We found decreased activity in several frontal and cingulate cortex areas in subjects with a severe WMH burden. No statistically significant associations were found when performing the brain-behavior statistical analysis for structural or functional data.

CONCLUSION

WMH burden has an effect on brain activity during fine motor control and the activity changes are associated with varying degrees of the total burden and distributions of WMH lesions. Collectively, our results shed new light on the potential impact of WMH on motor function in the context of aging and neurodegeneration.

Incidence, characteristics and outcome of post-stroke recrudescence in the Chinese population: a single-centre observational study

OBJECTIVES

The aim of our observational study was to investigate the incidence, clinical characteristics and outcome of post-stroke recrudescence (PSR) in the Chinese population.

DESIGN AND SETTING

Single-centre prospective observational study in China.

PARTICIPANTS

A total of 1114 patients who had a suspected stroke were prospectively screened from October 2020 to February 2022.

OUTCOME MEASURES

The primary outcome was the proportion of patients with functional independence defined as a score of 0-2 on the modified Rankin Scale (mRS) at 3 months. Secondary outcomes were: early neurological improvement (ENI), defined as a National Institutes of Health Stroke Scale (NIHSS) score of 0 or an improvement of ≥2 points from admission at 24 hours; mortality within 3 months; stroke recurrence within 3 months and length of stay in hospital.

RESULTS

A total of 959 patients with cerebral infarction and 30 patients without an available magnetic resonance imaging (MRI) scan were excluded. Among the 125 included patients, 27 cases of PSR (2.4%), 50 cases of transient ischaemic attack (TIA) (4.5%) and 48 cases of stroke mimics (SMs) (4.3%) were identified. A higher frequency of infection at admission (22.2% vs 2%, p=0.007) was observed in patients with PSR compared with patients with TIA, and a lower proportion of functional independence at 3 months (80% vs 98%, p=0.015) was seen. Patients with TIA had a higher frequency of ENI compared with patients with PSR and SMs (98% vs 59.3%, p<0.001; 98% vs 52.1%, p<0.001). Patients with PSR exhibited a higher frequency of grade 2 Fazekas deep white matter hyperintensity compared with those with SMs (33.3% vs 8.3%, p=0.010).

CONCLUSIONS

PSR is not uncommon in patients presenting with stroke symptoms and can be distinguished from TIA and SMs based on a combination of clinical features and trigger in the Chinese population. The neurological deficits of patients with PSR often resolve within several days following the resolution of the trigger.

Structural and Functional Brain Changes in Acute Takotsubo Syndrome

BACKGROUND

Takotsubo syndrome mimics an acute myocardial infarction, typically in the aftermath of mental or physical stress.

OBJECTIVES

The mechanism by which emotional processing in the context of stress leads to significant cardiac injury is poorly understood, so a full exploration of brain structure and function in takotsubo syndrome patients merits investigation.

METHODS

Twenty-five acute (<5 days) takotsubo patients and 25 control subjects were recruited into this observational cross-sectional study. Surface-based morphometry was carried out on magnetic resonance imaging (MRI) brain scans to extract cortical morphology based on volume, thickness, and surface area with the use of Freesurfer. Cortical morphology general linear models were corrected for age, sex, photoperiod, and total brain volume. Resting-state functional MRI and diffusion tensor tractography images were preprocessed and analyzed with the use of the Functional Magnetic Resonance Imaging of the Brain Diffusion Toolbox and Functional Connectivity Toolbox.

RESULTS

There was significantly smaller total white matter and subcortical gray matter volumes in takotsubo (P < 0.001), with smaller total brain surface area but increased total cortical thickness (both P < 0.001). Individual gray matter regions (hippocampus and others) were significantly smaller in takotsubo (P < 0.001); only thalamus and insula were larger (P < 0.001). There was significant hyperfunctional and hypofunctional connectivity in multiple areas, including thalamus-amygdala-insula and basal ganglia (P < 0.05). All structural tractography connections were increased in takotsubo (P < 0.05).

CONCLUSIONS

The authors showed smaller gray and white matter volumes driven by smaller cortical surface area, but increased cortical thickness and structural tractography connections with bidirectional changes in functional connectivity linked to emotion, language, reasoning, perception, and autonomic control. These are interventional targets in takotsubo patients' rehabilitation.

Ischemic stroke prediction of patients with carotid atherosclerotic stenosis via multi-modality fused network

Carotid atherosclerotic stenosis of the carotid artery is an important cause of ischemic cerebrovascular disease. The aim of this study was to predict the presence or absence of clinical symptoms in unknown patients by studying the existence or lack of symptoms of patients with carotid atherosclerotic stenosis. First, a deep neural network prediction model based on brain MRI imaging data of patients with multiple modalities is constructed; it uses the multi-modality features extracted from the neural network as inputs and the incidence of diagnosis as output to train the model. Then, a machine learning-based classification algorithm is developed to utilize the clinical features for comparison and evaluation. The experimental results showed that the deep learning model using imaging data could better predict the clinical symptom classification of patients. As part of preventive medicine, this study could help patients with carotid atherosclerosis narrowing to prepare for stroke prevention based on the prediction results.