Estimating Total Cerebral Microinfarct Burden From Diffusion-Weighted Imaging

Association of Acute Incidental Cerebral Microinfarcts With Subsequent Ischemic Stroke in Patients With Cancer: A Population-Based Study

BACKGROUND AND OBJECTIVES

Incidental diffuse-weighted imaging (DWI)-positive subcortical and cortical lesions, or acute incidental cerebral microinfarcts (CMIs), are a common type of brain ischemia, which can be detected on magnetic resonance DWI for approximately 2 weeks after occurrence. Acute incidental CMI was found to be more common in patients with cancer. Whether acute incidental CMI predicts future ischemic stroke is still unknown. We aimed to examine the association between acute incidental CMI in patients with cancer and subsequent ischemic stroke or transient ischemic attack (TIA).

METHODS

This is a retrospective cohort study. We used Clalit Health Services records, representing over half of the Israeli population, to identify adults with lung, breast, pancreatic, or colon cancer who underwent brain MRI between January 2014 and April 2020. We included patients who underwent scan between 1 year before cancer diagnosis and 1 year after diagnosis. Primary outcome was ischemic stroke or TIA using International Classification of Diseases, Ninth Revision codes. Secondary outcomes were intracranial hemorrhage (ICH) and mortality. Records were followed from first MRI until primary outcome, death, or end of follow-up (January 2023). Cox proportional hazards models were used to calculate hazard ratio (HR) for patients with and without acute incidental CMI, as a time-dependent covariate.

RESULTS

The study cohort included 1,618 patients with cancer, among whom, 59 (3.6%) had acute incidental CMI on at least 1 brain MRI. The median (interquartile range) time from acute incidental CMI to stroke or TIA was 26 days (14-84). On multivariable analysis, patients with acute incidental CMI had a higher stroke or TIA risk (HR 2.97, 95% CI 1.08-8.18, p = 0.035) compared with their non-CMI counterparts. Acute incidental CMIs were also associated with mortality after multivariable analysis (HR 2.76, 95% CI 2.06-3.71, p < 0.001); no association with ICH was found.

DISCUSSION

Acute incidental CMI on brain MRI in patients with active cancer is associated with an increased risk of near-future ischemic stroke or TIA and mortality. This finding might suggest that randomly detected acute incidental CMI in patients with cancer may guide primary cerebrovascular risk prevention and etiologic workup.

Lung cancer is associated with acute ongoing cerebral ischemia: A population-based study

BACKGROUND AND OBJECTIVES

Cerebral microinfarcts (CMIs) are the most common type of brain ischemia; however, they are extremely rare in the general population. CMIs can be detected by magnetic resonance diffusion-weighted imaging (MRI-DWI) only for a very short period of approximately 2 weeks after their formation and are associated with an increased stroke risk and cognitive impairment. We aimed to examine CMI detection rate in patients with lung cancer (LC), which is strongly associated with ischemic stroke risk relative to other cancer types.

METHODS

We used the Clalit Health Services record (representing more than 5 million patients) to identify adults with LC and breast, pancreatic, or colon cancer (non-lung cancer, NLC) who underwent brain magnetic resonance diffusion (MRI) scan within 5 years following cancer diagnosis. All brain MRI scans were reviewed, and CMIs were documented, as well as cardiovascular risk factors.

RESULTS

Our cohort contained a total of 2056 MRI scans of LC patients and 1598 of NLC patients. A total of 143 CMI were found in 73/2056 (3.5%) MRI scans of LC group compared to a total of 29 CMI in 22/1598 (1.4%) MRI scans of NLC (p < 0.01). Cancer type (e.g. LC vs NLC) was the only associated factor with CMI incidence on multivariate analysis. After calculating accumulated risk, we found an incidence of 2.5 CMI per year in LC patients and 0.5 in NLC.

DISCUSSION

CMIs are common findings in cancer patients, especially in LC patients and therefore might serve as a marker for occult brain ischemia, cognitive decline, and cancer-related stroke (CRS) risk.

Clinical and subclinical microemboli following neuroangiography in children

BACKGROUND

To assess the frequency, imaging appearances, and risk factors of brain microemboli following pediatric neuroangiography, as assessed by early diffusion-weighted MRI imaging (DWI).

METHODS

This single-center, retrospective analysis investigated early DWI post-pediatric neuroangiography. Patients aged 0-18 years who had diagnostic neuroangiography and DWI within a week postprocedure were included. Data on clinical and procedural parameters and MRI findings were recorded. Univariate and multivariate analyses were performed on the following risk factors: age, weight, vasculopathy, antiplatelet drug use, access type, intraprocedural heparin, procedure duration, neck arteries catheterized, and angiographic runs. A p-value<0.05 indicated statistical significance.

RESULTS

Eighty-two children were included (40.2% female), mean age 10.1±4.5 years (range: 7 months-17 years). There were no intraprocedural thromboembolic complications recognized. DWI positivity was seen following 3.6% (3/82) procedures: two with transient symptoms, and one instance of silent microemboli. There were no territorial infarcts or clinical stroke. Children with underlying vasculopathy had a higher risk of microemboli from angiography than children without vasculopathy (OR 31.6, p=0.02), and the OR of microemboli following transradial angiography was 79.1 (p=0.005) as compared with transfemoral angiography. Univariate and multivariate analysis showed a significant association between microemboli and number of angiographic runs (p=0.004). Follow-up MRI in all three patients showed no residual abnormal signal.

CONCLUSIONS

Cerebral microemboli are unusual following uncomplicated neuroangiography in children. However, in the presence of underlying vasculopathy and with transradial technique, the incidence approaches that reported in the adult literature. An increased association with the number of angiographic runs is an important and controllable factor.

Cerebral Microinfarcts Are Common in Undiagnosed Lung Cancer Patients: A Population-Based Study

Background. Cerebral microinfarcts (CMI) represent covert brain ischemia and were associated with stroke risk and cognitive impairment. Magnetic resonance imaging diffusion-weighted imaging (DWI) hyperintensities have been suggested to represent acute CMI. The relationship between malignancy and CMI is unknown. Aims. We aimed to examine whether CMI is more common in patients with undiagnosed lung cancer, and therefore might serve as a prediction marker for cognitive impairment or cancer-related stroke. Methods. We used the computerized database of Clalit Health Services (the largest healthcare provider in Israel) to identify adults diagnosed with lung cancer who had an MRI brain scan for any indication prior to cancer diagnosis. We analyzed DWI sequences, in order to evaluate CMI incidence in this population, and compared it to control groups of patients with other undiagnosed malignancies and patients without known cancer. Results. Altogether, we reviewed 1822 MRI brain scans, of which 497 scans were taken in patients with undiagnosed lung cancer, 543 scans of noncancer patients, and 793 scans of patients with other undiagnosed malignancies. In the lung cancer group, we found 24 CMI, compared with 4 in the noncancer group ( $p=0.04$ ) and 8 in the other cancer group ( $p=0.07$ ). Conclusions. CMI is common in undiagnosed lung cancer patients compare to other undiagnosed cancer types or noncancer patients. At the time of lung cancer diagnosis patients may be at risk for future stroke or cognitive decline.

Changes in Cerebral Blood Flow and Diffusion-Weighted Imaging Lesions After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a common subtype of stroke and places a great burden on the family and society with a high mortality and disability rate and a poor prognosis. Many findings from imaging and pathologic studies have suggested that cerebral ischemic lesions visualized on diffusion-weighted imaging (DWI) in patients with ICH are not rare and are generally considered to be associated with poor outcome, increased risk of recurrent (ischemic and hemorrhagic) stroke, cognitive impairment, and death. In this review, we describe the changes in cerebral blood flow (CBF) and DWI lesions after ICH and discuss the risk factors and possible mechanisms related to the occurrence of DWI lesions, such as cerebral microangiopathy, cerebral atherosclerosis, aggressive early blood pressure lowering, hyperglycemia, and inflammatory response. We also point out that a better understanding of cerebral DWI lesions will be a key step toward potential therapeutic interventions to improve long-term recovery for patients with ICH.

Diagnostic yield of diffusion-weighted brain MR imaging in patients with cognitive impairment: Large cohort study with 3,298 patients

Objective

There is a paucity of large cohort-based evidence regarding the need and added value of diffusion-weighted imaging (DWI) in patients attending outpatient clinic for cognitive impairment. We aimed to evaluate the diagnostic yield of DWI in patients attending outpatient clinic for cognitive impairment.

Materials and methods

This retrospective, observational, single-institution study included 3,298 consecutive patients (mean age ± SD, 71 years ± 10; 1,976 women) attending outpatient clinic for cognitive impairment with clinical dementia rating ≥ 0.5 who underwent brain MRI with DWI from January 2010 to February 2020. Diagnostic yield was defined as the proportion of patients in whom DWI supported the diagnosis that underlies cognitive impairment among all patients. Subgroup analyses were performed by age group and sex, and the Chi-square test was performed to compare the diagnostic yields between groups.

Results

The overall diagnostic yield of DWI in patients with cognitive impairment was 3.2% (106/3,298; 95% CI, 2.6–3.9%). The diagnostic yield was 2.5% (83/3,298) for acute or subacute infarct, which included recent small subcortical infarct for which the diagnostic yield was 1.6% (54/3,298). The diagnostic yield was 0.33% (11/3,298) for Creutzfeldt-Jakob disease (CJD), 0.15% (5/3,298) for transient global amnesia (TGA), 0.12% (4/3,298) for encephalitis and 0.09% (3/3,298) for lymphoma. There was a trend towards a higher diagnostic yield in the older age group with age ≥ 70 years old (3.6% vs 2.6%, P = .12). There was an incremental increase in the diagnostic yield from the age group 60–69 years (2.6%; 20/773) to 90–99 years (8.0%; 2/25).

Conclusion

Despite its low overall diagnostic yield, DWI supported the diagnosis of acute or subacute infarct, CJD, TGA, encephalitis and lymphoma that underlie cognitive impairment, and there was a trend towards a higher diagnostic yield in the older age group.

Microinfarcts in the Deep Gray Matter on 7T MRI: Risk Factors, MRI Correlates, and Relation to Cognitive Functioning-The SMART-MR Study

BACKGROUND AND PURPOSE

The clinical relevance of cortical microinfarcts has recently been established; however, studies on microinfarcts in the deep gray matter are lacking. We examined the risk factors and MR imaging correlates of microinfarcts in the deep gray matter on 7T MR imaging and their relation to cognitive functioning.

MATERIALS AND METHODS

Within the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART-MR) study, 213 patients (mean age, 68 [SD, 8] years) had a risk-factor assessment, 7T and 1.5T brain MR imaging, and a cognitive examination. Microinfarcts on 7T MR imaging were defined as lesions of <5 mm. Regression models were used to examine the age-adjusted associations among risk factors, MR imaging markers, and microinfarcts. Cognitive function was summarized as composite and domain-specific z scores.

RESULTS

A total of 47 microinfarcts were found in 28 patients (13%), most commonly in the thalamus. Older age, history of stroke, hypertension, and intima-media thickness were associated with microinfarcts. On 1.5T MR imaging, cerebellar infarcts (relative risk = 2.75; 95% CI, 1.4-5.33) and lacunes in the white (relative risk = 3.28; 95% CI, 3.28-6.04) and deep gray matter (relative risk = 3.06; 95% CI, 1.75-5.35) were associated with microinfarcts, and on 7T MR imaging cortical microinfarcts (relative risk = 2.33; 95% CI, 1.32-4.13). Microinfarcts were also associated with poorer global cognitive functioning (mean difference in the global z score between patients with multiple microinfarcts versus none = -0.97; 95% CI, -1.66 to -0.28, P = .006) and across all cognitive domains.

CONCLUSIONS

Microinfarcts in the deep gray matter on 7T MR imaging were associated with worse cognitive functioning and risk factors and MR imaging markers of small-vessel and large-vessel disease. Our findings suggest that microinfarcts in the deep gray matter may represent a novel imaging marker of vascular brain injury.

Ischemia in intracerebral hemorrhage: A comparative study of small-vessel and large-vessel diseases

Objective

This study aimed to compare effects of cerebral small‐vessel disease (cSVD) burden and cerebral artery stenosis (CAS) on acute ischemia in intracerebral hemorrhage (ICH) and their interaction with mean arterial pressure (MAP) change.

Methods

We recruited consecutive patients with acute primary ICH. Brain magnetic resonance imaging and angiography were performed to quantify diffusion‐weighted imaging (DWI) lesions, CAS, and cSVD markers, which were calculated for the total cSVD score. Multivariable regression models were adopted to explore their associations by DWI lesions size (<15 vs. ≥15 mm) and median MAP change stratification.

Results

Of 305 included patients (mean age 59.5 years, 67.9% males), 77 (25.2%) had DWI lesions (small, 79.2%; large, 20.8%) and 67 (22.0%) had moderate and severe CAS. In multivariable analysis, small DWI lesions were independently associated with higher total cSVD score (odds ratio [OR] 1.81, 95% confidence interval [CI] 1.36–2.41). and large DWI lesions were associated with more severe CAS (OR 2.51, 95% CI 1.17–5.38). This association was modified by MAP change (interaction p = 0.016), with stratified analysis showing an increased risk of large DWI lesions in severe CAS with greater MAP change (≥44 mmHg) (OR 3.48, 95% CI 1.13–10.74) but not with mild MAP change (<44 mmHg) (OR 1.21, 95% CI 0.20–7.34).

Interpretation

Total cSVD burden is associated with small DWI lesions, whereas the degree of CAS is associated with large DWI lesions, specifically with greater MAP change, suggesting that large‐artery atherosclerosis may be involved in ischemic brain injury, which is different from small‐vessel pathogenesis in ICH.

Exploration of the Mechanism Underlying the Association of Incident Microinfarct and Motor Deficit: A Preliminary Functional MRI Study

BACKGROUND

Cerebral microinfarcts (CMIs) might cause measurable disruption to brain connections and are associated with cognitive decline, but the association between CMIs and motor impairment is still unclear.

OBJECTIVE

To assess the CMIs effect on motor function in vivo and explore the potential neuropathological mechanism based on graph-based network method.

METHODS

We identified 133 non-demented middle-aged and elderly participants who underwent MRI scanning, cognitive, and motor assessment. The short physical performance battery (SPPB) assessed motor function, including balance, walking speed, and chair stand. We grouped participants into 34 incident CMIs carriers and 99 non-CMIs carriers as controls, depending on diffusion-weighted imaging. Then we assessed the independent CMIs effects on motor function and explored neural mechanisms of CMIs on motor impairment via mapping of degree centrality (DC) and eigenvector centrality (EC).

RESULTS

CMIs carriers had worse motor function than non-carriers. Linear regression analyses showed that CMIs independently contributed to motor function. CMIs carriers had decreased EC in the precuneus, while increased DC and EC in the middle temporal gyrus and increased DC in the inferior frontal gyrus compared to controls (p < 0.05, corrected). Correlation analyses showed that EC of precuneus was related to SPPB (r = 0.25) and balance (r = 0.27); however, DC (r = -0.25) and EC (r = -0.25) of middle temporal gyrus was related with SPPB in all participants (p < 0.05, corrected).

CONCLUSION

CMIs represent an independent risk factor for motor dysfunction. The relationship between CMIs and motor function may be attributed to suppression of functional hub region and compensatory activation of motor-related regions.

Assessing cortical cerebral microinfarcts on iron-sensitive MRI in cerebral small vessel disease

Recent studies suggest that a subset of cortical microinfarcts may be identifiable on T2* but invisible on T1 and T2 follow-up images. We aimed to investigate whether cortical microinfarcts are associated with iron accumulation after the acute stage. The RUN DMC - InTENse study is a serial MRI study including individuals with cerebral small vessel disease (SVD). 54 Participants underwent 10 monthly 3 T MRIs, including diffusion-weighted imaging, quantitative R1 (=1/T1), R2 (=1/T2), and R2* (=1/T2*) mapping, from which MRI parameters within areas corresponding to microinfarcts and control region of interests (ROIs) were retrieved within 16 participants. Finally, we compared pre- and post-lesional values with repeated measures ANOVA and post-hoc paired t-tests using the mean difference between lesion and control ROI values. We observed 21 acute cortical microinfarcts in 7 of the 54 participants (median age 69 years [IQR 66-74], 63% male). R2* maps demonstrated an increase in R2* values at the moment of the last available follow-up MRI (median [IQR], 5 [5-14] weeks after infarction) relative to prelesional values (p = .08), indicative of iron accumulation. Our data suggest that cortical microinfarcts are associated with increased R2* values, indicative of iron accumulation, possibly due to microhemorrhages, neuroinflammation or neurodegeneration, awaiting histopathological verification.

The Influence of Diffusion Weighted Imaging Lesions on Outcomes in Patients with Acute Spontaneous Intracerebral Hemorrhage

BACKGROUND/OBJECTIVE

Diffusion weighted imaging (DWI) lesions have been well described in patients with acute spontaneous intracerebral hemorrhage (sICH). However, there are limited data on the influence of these lesions on sICH functional outcomes. We conducted a prospective observational cohort study with blinded imaging and outcomes assessment to determine the influence of DWI lesions on long-term outcomes in patients with acute sICH. We hypothesized that DWI lesions are associated with worse modified Rankin Scale (mRS) at 3 months after hospital discharge.

METHODS

Consecutive sICH patients meeting study criteria were consented for an magnetic resonance imaging (MRI) scan of the brain and evaluated for remote DWI lesions by neuroradiologists blinded to the patients' hospital course. Blinded mRS outcomes were obtained at 3 months. Logistic regression was used to determine significant factors (p < 0.05) associated with worse functional outcomes defined as an mRS of 4-6. The generalized estimating equation (GEE) approach was used to investigate the effect of DWI lesions on dichotomized mRS (0-3 vs 4-6) longitudinally.

RESULTS

DWI lesions were found in 60 of 121 patients (49.6%). The presence of a DWI lesion was associated with increased odds for an mRS of 4-6 at 3 months (OR 5.987, 95% CI 1.409-25.435, p = 0.015) in logistic regression. Using the GEE model, patients with a DWI lesion were less likely to recover over time between 14 days/discharge and 3 months (p = 0.005).

CONCLUSIONS

DWI lesions are common in primary sICH, occurring in almost half of our cohort. Our data suggest that DWI lesions are associated with worse mRS at 3 months in good grade sICH and are predictive of impaired recovery after hospital discharge. Further research into the pathophysiologic mechanisms underlying DWI lesions may lead to novel treatment options that may improve outcomes associated with this devastating disease.

Acute intracerebral haemorrhage and diffusion-weighted imaging lesions: A meta-analysis

INTRODUCTION

Diffusion-weighted imaging lesions in intracerebral haemorrhage are related to a higher risk of recurrent intracerebral haemorrhage, cognitive damage, and mortality. However, it has been reported that the relationship between the risk of diffusion-weighted imaging lesions and intracerebral haemorrhage subtype or the risk factors for diffusion-weighted imaging lesions is variable. This meta-analysis was performed to evaluate this relationship.

METHODS

A systematic literature search up-to August 2020 was performed and 12 studies included 2815 subjects at the baseline with intracerebral haemorrhage. They were reporting relationships between the diffusion-weighted imaging lesions and intracerebral haemorrhage subtype or investigated the risk factors for diffusion-weighted imaging lesions. Odds ratio (OR) with 95% confidence intervals (CIs) was calculated to evaluate the prognostic role of diffusion-weighted imaging lesions and intracerebral haemorrhage subtype and investigated the risk factors for diffusion-weighted imaging lesions using the dichotomous and continuous method with a random or fixed-effect model.

RESULTS

Lobar intracerebral haemorrhage was not significantly related to a higher rate of diffusion-weighted imaging lesions (OR, 1.01; 95% CI, 0.75-1.36, P = .94) compared to the non-lobar intracerebral haemorrhage. Also, history of diabetes mellitus (OR, 1.15; 95% CI, 0.83-1.60, P = .39); history of smoking (OR, 0.95; 95% CI, 0.68-1.33, P = .76); history of hypercholesterolaemia (OR, 1.04; 95% CI, 0.73-1.48, P = .83) and history of ischaemic stroke (OR, 1.63; 95% CI, 0.57-4.66, P = .36) were not significantly related to higher rate of diffusion-weighted imaging lesions compared to no history of those factors. However, the history of hypertension was significantly related to a higher rate of diffusion-weighted imaging lesions (OR, 1.33; 95% CI, 1.04-1.70, P = .02) compared to no history of hypertension. Also, Subjects with diffusion-weighted imaging lesions had a greater decrease in systolic pressure in the acute phase of the intracerebral haemorrhage (OR, 10.23; 95% CI, 7.41-13.06, P < .001) compared to without diffusion-weighted imaging lesions.

CONCLUSIONS

Based on this meta-analysis, the history of hypertension may have an independent risk relationship with a higher rate of diffusion-weighted imaging lesions. Also, subjects with diffusion-weighted imaging lesions had a greater decrease in systolic pressure in the acute phase of the intracerebral haemorrhage compared to those without diffusion-weighted imaging lesions. This relationship forces us to recommend that identification of diffusion-weighted imaging lesions might add appreciated evidence to evaluate the progression of the underlying micro-angiopathy especially in subjects with a history of hypertension. Though further studies are needed to define the mechanisms by which these lesions may lead to cognitive damage and stroke reappearance.

The relation between acute intracerebral hemorrhage and diffusion-weighted imaging lesions: a meta-analysis

Diffusion-weighted imaging lesions in intracerebral hemorrhage are related to a higher risk of recurrent intracerebral hemorrhage, cognitive damage, and mortality. However, it has been reported that the relationship between the risk of diffusion-weighted imaging lesions and intracerebral hemorrhage subtype or the possible risk factors for diffusion-weighted imaging lesions is variable. This meta-analysis was performed to evaluate this relationship. A systematic literature search up-to August 2020 was performed and 12 studies included 2815 subjects at the baseline with intracerebral hemorrhage. Odds ratio (OR) or mean difference (MD) with 95% confidence intervals (CIs) was calculated to evaluate the prognostic role of diffusion-weighted imaging lesions and intracerebral hemorrhage subtype and investigated the possible risk factors for diffusion-weighted imaging lesions using the dichotomous and continuous methods with a random or fixed-effect model. Lobar intracerebral hemorrhage was not significantly related to a higher rate of diffusion-weighted imaging lesions (OR, 1.01; 95% CI, 0.75-1.36, p = 0.94) compared to the non-lobar intracerebral hemorrhage. Also, history of diabetes mellitus (OR, 1.15; 95% CI, 0.83-1.60, p = 0.39); history of smoking (OR, 0.95; 95% CI, 0.68-1.33, p = 0.76); history of hypercholesterolemia (OR, 1.04; 95% CI, 0.73-1.48, p = 0.83); and history of ischemic stroke (OR, 1.63; 95% CI, 0.57-4.66, p = 0.36) were not significantly related to higher rate of diffusion-weighted imaging lesions compared to no history of those factors. However, the history of hypertension was significantly related to a higher rate of diffusion-weighted imaging lesions (OR, 1.33; 95% CI, 1.04-1.70, p = 0.02) compared to no history of hypertension. Also, Subjects with diffusion-weighted imaging lesions had a greater decrease in systolic pressure in the acute phase of the intracerebral hemorrhage (MD, 10.23; 95% CI, 7.41-13.06, p < 0.001) compared to without diffusion-weighted imaging lesions. Based on this meta-analysis, the history of hypertension may have an independent risk relationship with a higher rate of diffusion-weighted imaging lesions. Also, subjects with diffusion-weighted imaging lesions had a greater decrease in systolic pressure in the acute phase of the intracerebral hemorrhage compared to those without diffusion-weighted imaging lesions. This relationship forces us to recommend that identification of diffusion-weighted imaging lesions might add appreciated evidence to evaluate the progression of the underlying micro-angiopathy especially in subjects with a history of hypertension. Though further studies are needed to define the mechanisms by which these lesions may lead to cognitive damage and stroke reappearance.

Association of neuroimaging markers of cerebral small vessel disease with short-term outcomes in patients with minor cerebrovascular events

Background

Increasing evidences have showed that neuroimaging markers of SVD can predict the short-term outcome of acute ischemic stroke (AIS). It is unclear that whether neuroimaging markers of SVD are also associated with short-term outcomes of minor cerebrovascular events. In the present study, we investigate neuroimaging markers of SVD in order to explore their roles in prediction of short-term outcome in patients with minor cerebrovascular events.

Methods

Consecutive first-ever stroke patients (n = 546) from the Affiliated Jiangning Hospital of Nanjing Medical University were enrolled. A total of 388 patients were enrolled according to minor cerebrovascular events definition (National Institutes of Health Stroke Scale Score ≤ 3) and exclusion criteria. MRI scans were performed within 7 days of stroke onset, and then neuroimaging markers of SVD including WMH, lacunes, cerebral microbleeds (CMB), and perivascular spaces (PVS), SVD burden scores were assessed. We completed baseline characteristics and evaluated the relationships of short-term outcomes to SVD neuroimaging markers and SVD scores. The 90-day modified Rankin Scale (mRS) was thought as primary outcome and was dichotomized as good functional outcome (mRS 0–1) and poor outcome (mRS 2–6). Secondary outcomes were stroke progression and stroke recurrence.

Results

Higher age, National Institutes of Health Stroke Scale (NIHSS) upon admission, lipoprotein-associated phospholipase A2 (LP-PLA2) and lacunes, Fazekas score were correlated with poor functional outcome (P < 0.05), But after adjusting for confounding variables, among the neuroimaging markers of cerebral small vessel disease, only Fazekas score (OR, 1.343; 95% confidence interval, 1.020–1.770; P = 0.036) was found to be associated with poor outcome at 90 days. Higher Fazekas and SVD scores were not associated with stroke progression or stroke recurrence.

Conclusion

WMH can predict the poor functional outcome of minor cerebrovascular events. Adding other neuroimaging markers of SVD and total SVD burden score, however, does not improve the prediction, which indicated WMH can as neuroimaging markers for guiding the treatment of minor cerebrovascular events.

Cerebral microinfarcts disruption of remote cortical thickness

INTRODUCTION

Cerebral microinfarcts (CMI) are common lesions, carrying an important contribution to small-vessel-related cognitive impairment. CMIs were previously found to cause local microstructural damage and disruption of white matter integrity. This study examines CMIs influence on cortical thickness in remote brain areas.

METHODS

Six small silent diffuse weighted imaging (DWI) lesions corresponding to subacute CMI were identified among five patients who underwent baseline and follow-up MRI scans from the Tel-Aviv Acute Brain Stroke Cohort (TABASCO). Regions of interest (ROIs) corresponding to the site of the DWI lesions and of the non-lesioned contralateral hemisphere (control ROI) were co-registered. DTI tractography was additionally performed to reconstruct the white matter tracts containing the ROIs. The normalized cortical thickness was calculated for the DWI lesional tract as well as for the contralateral non-lesional tract, and the lesion-to-control cortical thickness ratio (CTR) was calculated.

RESULTS

Post-lesional scans, performed 25.1 ± 1.2 months after CMI detection, demonstrated reduced mean CTR within the ROI from 1.8 to 1.1 (p = 0.032). There was no difference between the CTR of the right hemisphere relative to those on the left hemisphere, or between the CTR change of the cortical and non-cortical CMI.

DISCUSSION

This study demonstrated the prolonged influence of CMI on cortical thickness in remote ROI. The total number of CMIs is difficult to determine, however it has been shown that detecting even a single CMI suggests the existence of hundreds to thousands lesions. Therefore, the cumulative impact of these widely distributed lesions on cerebral cortex may have a significant contribution to the development of vascular cognitive impairment.

Cerebral Cortical Microinfarcts on Magnetic Resonance Imaging and Their Association With Cognition in Cerebral Amyloid Angiopathy

Background and Purpose- We aimed to explore the association between presence of cerebral cortical microinfarcts (CMIs) on magnetic resonance imaging and other small-vessel disease neuroimaging biomarkers in cerebral amyloid angiopathy (CAA) and to analyze the role of CMIs on individual cognitive domains and dementia conversion. Methods- Participants were recruited from an ongoing longitudinal research cohort of eligible CAA patients between March 2006 and October 2016. A total of 102 cases were included in the analysis that assessed the relationship of cortical CMIs to CAA neuroimaging markers. Ninety-five subjects had neuropsychological tests conducted within 1 month of magnetic resonance imaging scanning. Seventy-five nondemented CAA patients had cognitive evaluation data available during follow-up. Results- Among 102 patients enrolled, 40 patients had CMIs (39%) on magnetic resonance imaging. CMIs were uniformly distributed throughout the cortex without regional predilection ( P=0.971). The presence of CMIs was associated with lower total brain volume (odds ratio, 0.85; 95% CI, 0.74-0.98; P=0.025) and presence of cortical superficial siderosis (odds ratio, 2.66; 95% CI, 1.10-6.39; P=0.029). In 95 subjects with neuropsychological tests, presence of CMIs was associated with impaired executive function (β, -0.23; 95% CI, -0.44 to -0.02; P=0.036) and processing speed (β, -0.24; 95% CI, -0.45 to -0.04; P=0.020). Patients with CMIs had a higher cumulative dementia incidence compared with patients without CMIs ( P=0.043), whereas only baseline total brain volume (hazard ratio, 0.76; 95% CI, 0.62-0.92; P=0.006) independently predicted dementia conversion. Conclusions- Magnetic resonance imaging-detected CMIs in CAA correlated with greater overall disease burden. The presence of CMIs was associated with worse cognitive performance, whereas only total brain atrophy independently predicted dementia conversion.

Contribution of acute infarcts to cerebral small vessel disease progression

Objective

To determine the contribution of acute infarcts, evidenced by diffusion‐weighted imaging positive (DWI+) lesions, to progression of white matter hyperintensities (WMH) and other cerebral small vessel disease (SVD) markers.

Methods

We performed monthly 3T magnetic resonance imaging (MRI) for 10 consecutive months in 54 elderly individuals with SVD. MRI included high‐resolution multishell DWI, and 3‐dimensional fluid‐attenuated inversion recovery, T1, and susceptibility‐weighted imaging. We determined DWI+ lesion evolution, WMH progression rate (ml/mo), and number of incident lacunes and microbleeds, and calculated for each marker the proportion of progression explained by DWI+ lesions.

Results

We identified 39 DWI+ lesions on 21 of 472 DWI scans in 9 of 54 subjects. Of the 36 DWI+ lesions with follow‐up MRI, 2 evolved into WMH, 4 evolved into a lacune (3 with cavity <3mm), 3 evolved into a microbleed, and 27 were not detectable on follow‐up. WMH volume increased at a median rate of 0.027 ml/mo (interquartile range = 0.005–0.073), but was not significantly higher in subjects with DWI+ lesions compared to those without (p = 0.195). Of the 2 DWI+ lesions evolving into WMH on follow‐up, one explained 23% of the total WMH volume increase in one subject, whereas the WMH regressed in the other subject. DWI+ lesions preceded 4 of 5 incident lacunes and 3 of 10 incident microbleeds.

Interpretation

DWI+ lesions explain only a small proportion of the total WMH progression. Hence, WMH progression seems to be mostly driven by factors other than acute infarcts. DWI+ lesions explain the majority of incident lacunes and small cavities, and almost one‐third of incident microbleeds, confirming that WMH, lacunes, and microbleeds, although heterogeneous on MRI, can have a common initial appearance on MRI. ANN NEUROL 2019;86:582–592

Treatment Approaches to Lacunar Stroke

Lacunar strokes are appropriately named for their ability to cavitate and form ponds or "little lakes" (Latin: lacune -ae meaning pond or pit is a diminutive form of lacus meaning lake). They account for a substantial proportion of both symptomatic and asymptomatic ischemic strokes. In recent years, there have been several advances in the management of large vessel occlusions. New therapies such as non-vitamin K antagonist oral anticoagulants and left atrial appendage closure have recently been developed to improve stroke prevention in atrial fibrillation; however, the treatment of small vessel disease-related strokes lags frustratingly behind. Since Fisher characterized the lacunar syndromes and associated infarcts in the late 1960s, there have been no therapies specifically targeting lacunar stroke. Unfortunately, many therapeutic agents used for the treatment of ischemic stroke in general offer only a modest benefit in reducing recurrent stroke while adding to the risk of intracerebral hemorrhage and systemic bleeding. Escalation of antithrombotic treatments beyond standard single antiplatelet agents has not been effective in long-term lacunar stroke prevention efforts, unequivocally increasing intracerebral hemorrhage risk without providing a significant benefit. In this review, we critically review the available treatments for lacunar stroke based on evidence from clinical trials. For several of the major drugs, we summarize the adverse effects in the context of this unique patient population. We also discuss the role of neuroprotective therapies and neural repair strategies as they may relate to recovery from lacunar stroke.

Pathophysiology of Lacunar Stroke: History's Mysteries and Modern Interpretations

Since the term "lacune" was adopted in the 1800s to describe infarctions from cerebral small vessels, their underlying pathophysiological basis remained obscure until the 1960s when Charles Miller Fisher performed several autopsy studies of stroke patients. He observed that the vessels displayed segmental arteriolar disorganization that was associated with vessel enlargement, hemorrhage, and fibrinoid deposition. He coined the term "lipohyalinosis" to describe the microvascular mechanism that engenders small subcortical infarcts in the absence of a compelling embolic source. Since Fisher's early descriptions of lipohyalinosis and lacunar stroke (LS), there have been many advancements in the understanding of this disease process. Herein, we review lipohyalinosis as it relates to modern concepts of cerebral small vessel disease (cSVD). We discuss clinical classifications of LS as well as radiographic definitions based on modern neuroimaging techniques. We provide a broad and comprehensive overview of LS pathophysiology both at the vessel and parenchymal levels. We also comment on the role of biomarkers, the possibility of systemic disease processes, and advancements in the genetics of cSVD. Lastly, we assess preclinical models that can aid in studying LS disease pathogenesis. Enhanced understanding of this highly prevalent disease will allow for the identification of novel therapeutic targets capable of mitigating disease sequelae.

Asymptomatic Cerebral Small Vessel Disease: Insights from Population-Based Studies

Cerebral small vessel disease (CSVD) is a common group of neurological conditions that confer a significant burden of morbidity and mortality worldwide. In most cases, CSVD is only recognized in its advanced stages once its symptomatic sequelae develop. However, its significance in asymptomatic healthy populations remains poorly defined. In population-based studies of presumed healthy elderly individuals, CSVD neuroimaging markers including white matter hyperintensities, lacunes, cerebral microbleeds, enlarged perivascular spaces, cortical superficial siderosis, and cerebral microinfarcts are frequently detected. While the presence of these imaging markers may reflect unique mechanisms at play, there are likely shared pathways underlying CSVD. Herein, we aim to assess the etiology and significance of these individual biomarkers by focusing in asymptomatic populations at an epidemiological level. By primarily examining population-based studies, we explore the risk factors that are involved in the formation and progression of these biomarkers. Through a critical semi-systematic review, we aim to characterize “asymptomatic” CSVD, review screening modalities, and draw associations from observational studies in clinical populations. Lastly, we highlight areas of research (including therapeutic approaches) in which further investigation is needed to better understand asymptomatic CSVD.

Clinical relevance of acute cerebral microinfarcts in vascular cognitive impairment

Objective

To determine the occurrence of acute cerebral microinfarcts (ACMIs) in memory clinic patients and relate their presence to vascular risk and cognitive profile, CSF and neuroimaging markers, and clinical outcome.

Methods

The TRACE-VCI study is a memory clinic cohort of patients with vascular brain injury on MRI (i.e., possible vascular cognitive impairment [VCI]). We included 783 patients (mean age 67.6 ± 8.5, 46% female) with available 3T diffusion-weighted imaging (DWI). ACMIs were defined as supratentorial DWI hyperintensities <5 mm with a corresponding hypo/isointense apparent diffusion coefficient signal and iso/hyperintense T2*-weighted signal.

Results

A total of 23 ACMIs were found in 16 of the 783 patients (2.0%). Patients with ACMIs did not differ in vascular risk or cognitive profile, but were more often diagnosed with vascular dementia (odds ratio [OR] 5.1; 95% confidence interval [CI] 1.4–18.9, p = 0.014). ACMI presence was associated with lower levels of β-amyloid (p < 0.004) and with vascular imaging markers (lacunar infarcts: OR 3.5, CI 1.3–9.6, p = 0.015; nonlacunar infarcts: OR 4.1, CI 1.4–12.5, p = 0.012; severe white matter hyperintensities: OR 4.8, CI 1.7–13.8, p = 0.004; microbleeds: OR 18.9, CI 2.5–144.0, p = 0.0001). After a median follow-up of 2.1 years, the risk of poor clinical outcome (composite of marked cognitive decline, major vascular event, death, and institutionalization) was increased among patients with ACMIs (hazard ratio 3.0; 1.4–6.0, p = 0.005).

Conclusion

In patients with possible VCI, ACMI presence was associated with a high burden of cerebrovascular disease of both small and large vessel etiology and poor clinical outcome. ACMIs may thus be a novel marker of active vascular brain injury in these patients.

Juxtacortical lesions are associated with seizures in cerebral small vessel disease

BACKGROUND AND OBJECTIVE

Small vessel cerebrovascular disease (SVCD) can manifest with epileptic seizures and transient ischemic attacks (TIA). This study was designed to test if the extent and spatial distribution of SVCD differs in patients with focal impaired awareness seizures (FIAS) from patients with TIA.

METHODS

This is a retrospective single-center case-control study of elderly patients at a high cardiovascular risk. 118 patients with FIAS (cases) were compared to a matched control group of 118 patients with TIA. The extent and spatial distribution of white matter hyperintensities (WMH) characteristic for SVCD and medial temporal lobe atrophy were analyzed on magnetic resonance imaging (MRI) obtained at admission. The Fazekas, Wahlund, and Scheltens scales were used for grading. Juxtacortical small lesions were analyzed separately.

RESULTS

FIAS patients were observed to have more extensive WMH (p < 0.001) and more pronounced medial temporal lobe atrophy (p < 0.001) than TIA patients. WMH in FIAS patients were predominantly localized in supratentorial white matter compared to TIA patients (p < 0.001). Juxtacortical hyperintensities were far more common in FIAS patients than in TIA patients (80.5% vs. 22.0%; p < 0.001). Multivariate analysis revealed juxtacortical small lesions as strong independent predictor (OR, 95% CI 12.8, 6.7-24.3) and medial temporal lobe atrophy as further independent predictor of FIAS (3.1, 1.3-7.1).

CONCLUSIONS

Juxtacortical small lesions and to a smaller extent medial temporal lobe atrophy are associated with epileptic seizures in elderly patients at a high cardiovascular risk. This observation may provide a structural explanation for epilepsy in SVCD. Juxtacortical small lesions in SVCD should be considered a structural cause for epilepsy and promote anticonvulsive therapy after a first seizure.

Diffusion-Weighted Imaging Hyperintensities in Subtypes of Acute Intracerebral Hemorrhage: Meta-Analysis

Background and Purpose- Diffusion-weighted imaging (DWI) hyperintensities in intracerebral hemorrhage (ICH) are associated with increased risk of recurrent ICH, cognitive impairment, and death, but whether these lesions are specific to a subtype of ICH remains uncertain. We investigated the association between DWI lesions and ICH subtype and explored the risk factors for DWI lesions. Methods- In a systematic review of ICH studies, we identified those reporting prevalence of DWI lesions. Two reviewers independently assessed study eligibility and risk of bias and collected data. We determined the pooled prevalence of DWI lesions within 90 days after ICH onset for cerebral amyloid angiopathy- and hypertensive angiopathy-related ICH using random-effects meta-analysis. We calculated odds ratios to compare prevalence of DWI lesions by ICH subtype and to assess risk factors for DWI lesions. Results- Eleven studies (1910 patients) were included. The pooled prevalence of DWI lesions was 18.9% (95% CI, 11.1-26.7) in cerebral amyloid angiopathy- and 21.0% (95% CI, 15.3-26.6) in hypertensive angiopathy-related ICH. There was no difference in the prevalence of DWI lesions between cerebral amyloid angiopathy- (64/292 [21.9%]) and hypertensive angiopathy-related ICH (79/370 [21.4%]; odds ratio, 1.25; 95% CI, 0.73-2.15) in the 5 studies reporting data on both ICH pathogeneses. In all ICH, presence of DWI lesions was associated with neuroimaging features of microangiopathy (leukoaraiosis extension, previous ICH, and presence, and number of microbleeds) but not with vascular risk factors or the use of antithrombotic therapies. Conclusions- Prevalence of DWI lesions in acute ICH averages 20%, with no difference between cerebral amyloid angiopathy- and hypertensive angiopathy-related ICH. Detection of DWI lesions may add valuable information to assess the progression of the underlying microangiopathy.

Cortical Cerebral Microinfarcts on 3 Tesla MRI in Patients with Vascular Cognitive Impairment

BACKGROUND

Cerebral microinfarcts (CMIs) are small ischemic lesions that are a common neuropathological finding in patients with stroke or dementia. CMIs in the cortex can now be detected in vivo on 3 Tesla MRI.

OBJECTIVE

To determine the occurrence of CMIs and associated clinical features in patients with possible vascular cognitive impairment (VCI).

METHOD

182 memory-clinic patients (mean age 71.4±10.6, 55% male) with vascular injury on brain MRI (i.e., possible VCI) underwent a standardized work-up including 3 Tesla MRI and cognitive assessment. A control group consisted of 70 cognitively normal subjects (mean age 70.6±4.7, 60% male). Cortical CMIs and other neuroimaging markers of vascular brain injury were rated according to established criteria.

RESULT

Occurrence of CMIs was higher (20%) in patients compared to controls (10%). Among patients, the presence of CMIs was associated with male sex, history of stroke, infarcts, and white matter hyperintensities. CMI presence was also associated with a diagnosis of vascular dementia and reduced performance in multiple cognitive domains.

CONCLUSION

CMIs on 3 Tesla MRI are common in patients with possible VCI and co-occur with imaging markers of small and large vessel disease, likely reflecting a heterogeneous etiology. CMIs are associated with worse cognitive performance, independent of other markers of vascular brain injury.

Signal Change of Acute Cortical and Juxtacortical Microinfarction on Follow-Up MRI

BACKGROUND AND PURPOSE

Although the clinical importance of cortical microinfarcts has become well-recognized recently, the evolution of cortical microinfarcts on MR imaging is not fully understood. The aim of this study was to examine the temporal changes in acute cortical microinfarcts using susceptibility-weighted imaging and conventional MR imaging.

MATERIALS AND METHODS

Patients with acute infarcts located in the cortical and/or juxtacortical region measuring ≤10 mm in axial diameter based on diffusion-weighted imaging who had a follow-up 3T MR imaging were retrospectively included in the study. All lesions did not show hypointensity on initial T2*WI. For cortical and/or juxtacortical microinfarcts detected on initial DWI, 2 neuroradiologists evaluated the follow-up MR imaging (T2WI, FLAIR, T2*WI, and SWI) and assessed lesion signal intensities and locations (cortical microinfarcts or microinfarcts with juxtacortical white matter involvement).

RESULTS

On initial DWI, 2 radiologists observed 180 cortical and/or juxtacortical microinfarcts in 35 MR imaging examinations in 25 patients; on follow-up, the neuroradiologists identified 29 cortical microinfarcts (16%) on T2WI, 9 (5%) on FLAIR, 4 (2%) on T2*, and 97 (54%) on SWI. All cortical microinfarcts detected with any follow-up MR imaging showed hyperintensity on T2WI/FLAIR and/or hypointensity on T2*WI and SWI.

CONCLUSIONS

SWI revealed conversion (paramagnetic susceptibility changes) of acute cortical microinfarcts, suggesting that a substantial number of cortical microinfarcts may contain hemorrhagic components.

Small Hyperintensities in the Area of the Perforating Arteries in Patients with Seizure

Background/Aim: We previously observed spotty hyperintense lesions in the region of the perforating arteries on peri-ictal diffusion-weighted imaging (DWI); however, no report has formally described these findings. The aim of this study was to investigate focal intensities on peri-ictal DWI, and to evaluate the clinical significance of these lesions. Methods: We conducted a retrospective review of 677 consecutive patients with seizure who completed peri-ictal DWI within 24 h after seizure onset. Patients were grouped according to the presence or absence of diffusion hyperintense lesions (DHLs) in the region of the perforating arteries. We compared clinical and imaging characteristics between these 2 groups. Results: Among 677 patients, 23 patients (3.4%) had DHLs. Analyses of apparent diffusion coefficient values and fluid attenuated inversion recovery images suggested that DHLs were acute or subacute ischemic lesions that had appeared prior to seizure onset. Patients with DHLs were more likely to be older in age, have atrial fibrillation, and coronary artery disease, and have more severe deep white matter hyperintensity or leukoaraiosis compared to patients without DHLs. Conclusion: DHLs detected on peri-ictal DWI may represent incidental acute cerebral microinfarcts in the aging brain, especially in patients with small vessel disease.

Incidence and Etiology of Microinfarcts in Patients with Ischemic Stroke

BACKGROUND AND PURPOSE

Cerebral microinfarcts (CMI) are associated with intracerebral hemorrhage due to small vessel disease (SVD) in studies not including an ischemic etiologic workup. We aimed to determine their incidence and potential causes in a large ischemic stroke (IS) cohort.

METHODS

Consecutive patients with MRI-confirmed IS within 72 hours of onset were enrolled. Subjects had either single high-risk embolic source (cardioembolic or large vessel disease) or no embolic source. CMIs were classified by their relationship to the primary infarct as within or outside the same vascular territory. White matter hyperintensities (WMH) and microbleeds were markers SVD severity. Multivariable regression tested the association between CMIs and potential etiologies.

RESULTS

We analyzed 946 IS patients, mean age 69 ± 15 years, 46% female. We detected CMI (≤5 mm) on diffusion-weighted imaging in 269 (28%) subjects, 190 (71%) within the vascular territory of the primary infarct. Large-vessel atherosclerosis (P <.001), cardioembolic source (P <.001), higher WMH (P = .032) and lower systolic blood pressure (SBP, P = .024) were independently associated with the presence of CMI. While SBP was associated with CMI in any location (P <.05), WMH was only associated with CMI outside the territory of the primary infarct (P = .033), and large vessel atherosclerosis with CMI within the primary infarct territory (P = .004).

CONCLUSIONS

CMIs occurring within the vascular territory of a larger infarct are more likely embolic, but those occurring outside are probably related to SVD. Our findings suggest a role for SVD in pathogenesis of CMIs and emphasize the importance of etiologic workup to identify alternate etiologies.

Does pathology of small venules contribute to cerebral microinfarcts and dementia?

Microinfarcts are small, but strikingly common, ischemic brain lesions in the aging human brain. There is mounting evidence that microinfarcts contribute to vascular cognitive impairment and dementia, but the origins of microinfarcts are unclear. Understanding the vascular pathologies that cause microinfarcts may yield strategies to prevent their occurrence and reduce their deleterious effects on brain function. Current thinking suggests that cortical microinfarcts arise from the occlusion of penetrating arterioles, which are responsible for delivering oxygenated blood to small volumes of tissue. Unexpectedly, pre-clinical studies have shown that the occlusion of penetrating venules, which drain deoxygenated blood from cortex, lead to microinfarcts that appear identical to those resulting from arteriole occlusion. Here we discuss the idea that cerebral venule pathology could be an overlooked source for brain microinfarcts in humans. This article is part of the Special Issue "Vascular Dementia". Cover Image for this Issue: doi: 10.1111/jnc.14167.

Only White Matter Hyperintensities Predicts Post-Stroke Cognitive Performances Among Cerebral Small Vessel Disease Markers: Results from the TABASCO Study

BACKGROUND

White matter hyperintensities (WMH) were shown to predict cognitive decline following stroke or transient ischemic attack (TIA). However, WMH are only one among other radiological markers of cerebral small vessel disease (SVD).

OBJECTIVE

The aim of this study was to determine whether adding other SVD markers to WMH improves prediction of post-stroke cognitive performances.

METHODS

Consecutive first-ever stroke or TIA patients (n = 266) from the Tel Aviv Acute Brain Stroke Cohort (TABASCO) study were enrolled. MRI scans were performed within seven days of stroke onset. We evaluated the relationship between cognitive performances one year following stroke, and previously suggested total SVD burden score including WMH, lacunes, cerebral microbleeds (CMB), and perivascular spaces (PVS).

RESULTS

Significant negative associations were found between WMH and cognition (p < 0.05). Adding other SVD markers (lacunes, CMB, PVS) to WMH did not improve predication of post-stroke cognitive performances. Negative correlations between SVD burden score and cognitive scores were observed for global cognitive, memory, and visual spatial scores (all p < 0.05). However, following an adjustment for confounders, no associations remained significant.

CONCLUSION

WMH score was associated with poor post-stroke cognitive performance. Adding other SVD markers or SVD burden score, however, did not improve prediction.

Remote Diffusion-Weighted Imaging Lesions in Intracerebral Hemorrhage: Characteristics, Mechanisms, Outcomes, and Therapeutic Implications

Spontaneous intracerebral hemorrhage (ICH) is one of the most fatal form of stroke, with high mortality and disability rate. Small diffusion-weighed imaging lesions are not rare to see in regions remote from the hematoma after ICH and have been generally considered as related with poor outcome. In this review, we described the characteristics of remote ischemic lesions, discussed the possible mechanisms and clinical outcomes of these lesions, and evaluated the potential therapeutic implications.

Evolution of DWI lesions in cerebral amyloid angiopathy: Evidence for ischemia

OBJECTIVE

To address the pathophysiologic nature of small diffusion-weighted imaging (DWI) lesions in patients with cerebral amyloid angiopathy (CAA) who underwent serial MRI. Specifically, we tested (1) whether DWI lesions occurred preferentially in individuals with prior DWI lesions, (2) the cross-sectional association with chronic cortical cerebral microinfarcts (CMIs), and (3) the evolution of DWI lesions over time.

METHODS

Patients with probable CAA (n = 79) who underwent at least 2 MRI sessions were included. DWI lesions were assessed at each available time point. Lesion appearance and characteristics were assessed on available structural follow-up images. Presence and burden of other neuroimaging markers of small vessel disease (white matter hyperintensities, cerebral microbleeds, cortical superficial siderosis, and chronic cortical CMIs) were assessed as well.

RESULTS

Among 221 DWI scans (79 patients with 2 DWI scans; 40 with ≥3), 60 DWI lesions were found in 28 patients. Patients with DWI lesions at baseline were not more likely to have additional DWI lesions on follow-up compared to patients without DWI lesions at baseline. DWI lesions were associated with chronic cortical CMIs and cortical superficial siderosis, but not with other markers. For 39/60 DWI lesions, >1 MRI sequence was available at follow-up to determine lesion evolution. Twenty-four (62%) were demarcated as chronic lesions on follow-up MRI. Five appeared as cavitations, 18 as noncavitated infarcts, and 1 underwent hemorrhagic transformation.

CONCLUSIONS

Based on their neuroimaging signature as well as their association with chronic cortical CMIs, DWI lesions appear to have an ischemic origin and represent one part of the CMI spectrum.

Functional deficits induced by cortical microinfarcts

Clinical studies have revealed a strong link between increased burden of cerebral microinfarcts and risk for cognitive impairment. Since the sum of tissue damage incurred by microinfarcts is a miniscule percentage of total brain volume, we hypothesized that microinfarcts disrupt brain function beyond the injury site visible to histological or radiological examination. We tested this idea using a mouse model of microinfarcts, where single penetrating vessels that supply mouse cortex were occluded by targeted photothrombosis. We found that in vivo structural and diffusion MRI reliably reported the acute microinfarct core, based on spatial co-registrations with post-mortem stains of neuronal viability. Consistent with our hypothesis, c-Fos assays for neuronal activity and in vivo imaging of single vessel hemodynamics both reported functional deficits in viable peri-lesional tissues beyond the microinfarct core. We estimated that the volume of tissue with functional deficit in cortex was at least 12-fold greater than the volume of the microinfarct core. Impaired hemodynamic responses in peri-lesional tissues persisted at least 14 days, and were attributed to lasting deficits in neuronal circuitry or neurovascular coupling. These data show how individually miniscule microinfarcts could contribute to broader brain dysfunction during vascular cognitive impairment and dementia.

Efficacy of alogliptin combined with motor imagery under hyperbaric oxygen in diabetic nephropathy with silent cerebral infarction

In the present study, we evaluated the curative effect of dipeptidyl peptidase-IV (DPP-IV) inhibitor alogliptin combined with motor imagery under hyperbaric oxygen in diabetic nephropathy (DN) with silent cerebral infarction (SCI). Two-hundred newly diagnosed DN patients with and without SCI were included. The SCI patients were divided into two treatment groups: Alogliptin (A group, n=50) and alogliptin combined with motor imagery under hyperbaric oxygen (B group, n=50). The degrees of neurocognitive dysfunction were evaluated at baseline and after 6 months of treatment. Thromboelastograms (TEGs) mapping were conducted. Serum glycoprotein VI (GPVI) mRNA expression and urine 11-DH-TXB₂ levels were determined. Compared to group A patients, the severity of neurofunctional defects, GPVI mRNA expression and 11-DH-TXB₂ levels were significantly lower in group B (P<0.05), while comprehensive, MoCA scores were higher in group B. The MoCA subscores of visuospatial/executive function, attention and concentration were significantly higher compared to group A (P<0.05). The sub-scores of computation, abstract thinking, language competence, memory and orientation were also higher in group B but the differences were not significant (P>0.05). TEG indexes were improved in both groups after treatment as manifested by increased R and K values, but there was significant improvement in group B. Intra-group comparisons revealed a time-dependent effect of treatment. In conclusion, the treatment of alogliptin combined with motor imagery under hyperbaric oxygen can better promote thrombolysis absorption, restore brain damage and improve neurocognitive function in DN with silent cerebral infarction.

Detection, risk factors, and functional consequences of cerebral microinfarcts

Cerebral microinfarcts are small lesions that are presumed to be ischaemic. Despite the small size of these lesions, affected individuals can have hundreds to thousands of cerebral microinfarcts, which cause measurable disruption to structural brain connections, and are associated with dementia that is independent of Alzheimer's disease pathology or larger infarcts (ie, lacunar infarcts, and large cortical and non-lacunar subcortical infarcts). Substantial progress has been made with regard to understanding risk factors and functional consequences of cerebral microinfarcts, partly driven by new in-vivo detection methods and the development of animal models that closely mimic multiple aspects of cerebral microinfarcts in human beings. Evidence from these advances suggests that cerebral microinfarcts can be manifestations of both small vessel and large vessel disease, that cerebral microinfarcts are independently associated with cognitive impairment, and that these lesions are likely to cause damage to brain structure and function that extends beyond their actual lesion boundaries. Criteria for the identification of cerebral microinfarcts with in-vivo MRI are provided to support further studies of the association between these lesions and cerebrovascular disease and dementia.

Emerging concepts in sporadic cerebral amyloid angiopathy

Sporadic cerebral amyloid angiopathy is a common, well-defined small vessel disease and a largely untreatable cause of intracerebral haemorrhage and contributor to age-related cognitive decline. The term 'cerebral amyloid angiopathy' now encompasses not only a specific cerebrovascular pathological finding, but also different clinical syndromes (both acute and progressive), brain parenchymal lesions seen on neuroimaging and a set of diagnostic criteria-the Boston criteria, which have resulted in increasingly detected disease during life. Over the past few years, it has become clear that, at the pathophysiological level, cerebral amyloid angiopathy appears to be in part a protein elimination failure angiopathy and that this dysfunction is a feed-forward process, which potentially leads to worsening vascular amyloid-β accumulation, activation of vascular injury pathways and impaired vascular physiology. From a clinical standpoint, cerebral amyloid angiopathy is characterized by individual focal lesions (microbleeds, cortical superficial siderosis, microinfarcts) and large-scale alterations (white matter hyperintensities, structural connectivity, cortical thickness), both cortical and subcortical. This review provides an interdisciplinary critical outlook on various emerging and changing concepts in the field, illustrating mechanisms associated with amyloid cerebrovascular pathology and neurological dysfunction.

Impact of multiple pathologies on the threshold for clinically overt dementia

Longitudinal clinical-pathological studies have increasingly recognized the importance of mixed pathologies (the coexistence of one or more neurodegenerative and cerebrovascular disease pathologies) as important factors in the development of Alzheimer's disease (AD) and other forms of dementia. Older persons with AD pathology, often have concomitant cerebrovascular disease pathologies (macroinfarcts, microinfarcts, atherosclerosis, arteriolosclerosis, cerebral amyloid angiopathy) as well as other concomitant neurodegenerative disease pathologies (Lewy bodies, TDP-43, hippocampal sclerosis). These additional pathologies lower the threshold for clinical diagnosis of AD. Many of these findings from pathologic studies, especially for CVD, have been confirmed using sophisticated neuroimaging technologies. In vivo biomarker studies are necessary to provide an understanding of specific pathologic contributions and time course relationships along the spectrum of accumulating pathologies. In this review, we provide a clinical-pathological perspective on the role of multiple brain pathologies in dementia followed by a review of the available clinical and biomarker data on some of the mixed pathologies.

Vascular Cognitive Impairment

Cerebrovascular disease typically manifests with stroke, cognitive impairment, or both. Vascular cognitive impairment refers to all forms of cognitive disorder associated with cerebrovascular disease, regardless of the specific mechanisms involved. It encompasses the full range of cognitive deficits from mild cognitive impairment to dementia. In principle, any of the multiple causes of clinical stroke can cause vascular cognitive impairment. Recent work further highlights a role of microinfarcts, microhemorrhages, strategic white matter tracts, loss of microstructural tissue integrity, and secondary neurodegeneration. Vascular brain injury results in loss of structural and functional connectivity and, hence, compromise of functional networks within the brain. Vascular cognitive impairment is common both after stroke and in stroke-free individuals presenting to dementia clinics, and vascular pathology frequently coexists with neurodegenerative pathology, resulting in mixed forms of mild cognitive impairment or dementia. Vascular dementia is now recognized as the second most common form of dementia after Alzheimer's disease, and there is increasing awareness that targeting vascular risk may help to prevent dementia, even of the Alzheimer type. Recent advances in neuroimaging, neuropathology, epidemiology, and genetics have led to a deeper understanding of how vascular disease affects cognition. These new findings provide an opportunity for the present reappraisal of vascular cognitive impairment. We further briefly address current therapeutic concepts.

Imaging markers of cerebrovascular pathologies: Pathophysiology, clinical presentation, and risk factors

Cerebrovascular pathologies (CVPs) are common pathologies associated with age-related cognitive decline along with Alzheimer disease pathologies. The impact of CVP on the prevalence of dementia is increasingly being recognized. The goal of this review is to improve our understanding of the pathophysiological underpinnings and the multimodal magnetic resonance imaging and positron emission tomography imaging changes that are associated with the hallmarks of CVP. This knowledge will facilitate the development of early detection, intervention, and prevention strategies that may contribute to lowering the risk of dementia. In this review, we will first discuss currently known risk factors of CVPs including cardiovascular, lifestyle, genetic, sex differences, and head injury. Next, we will focus on the pathophysiology of CVPs and their impact on neurodegeneration and downstream cognitive impairment. Specifically, we will discuss three of the most common cerebrovascular lesions seen on MRI: white-matter hyperintensity, microbleeds, and infarcts. Finally, we will discuss the unanswered open questions in this field.