Greater Cincinnati/Northern Kentucky Stroke Study: volume of first-ever ischemic stroke among blacks in a population-based study

Health Factors Associated With Development and Severity of Poststroke Dysphagia: An Epidemiological Investigation

BACKGROUND

Dysphagia after stroke is common and can impact morbidity and death. The purpose of this population-based study was to determine specific epidemiological and health risk factors that impact development of dysphagia after acute stroke.

METHODS AND RESULTS

Ischemic and hemorrhagic stroke cases from 2010 and 2015 were identified via chart review from the GCNKSS (Greater Cincinnati Northern Kentucky Stroke Study), a representative sample of ≈1.3 million adults from southwestern Ohio and northern Kentucky. Dysphagia status was determined on the basis of clinical assessments and necessity for alternative access to nutrition via nasogastric or percutaneous endoscopic gastrostomy tube placement. Comparisons between patients with and without dysphagia were made to determine differences in baseline characteristics and premorbid conditions. Multivariable logistic regression determined factors associated with increased risk of dysphagia. Dysphagia status was ascertained from 4139 cases (1709 with dysphagia). Logistic regression showed that increased age, Black race, higher National Institutes of Health Stroke Scale score at admission, having a hemorrhagic stroke (versus infarct), and right hemispheric stroke increased the risk of developing dysphagia after stroke. Factors associated with reduced risk included history of high cholesterol, lower prestroke modified Rankin Scale score, and white matter disease.

CONCLUSIONS

This study replicated previous findings of variables associated with dysphagia (older age, worse stroke, right-sided hemorrhagic lesions), whereas other variables identified were without clear biological rationale (eg, Black race, history of high cholesterol, and presence of white matter disease) and should be investigated in future studies to determine biological relevance and potential influence in stroke recovery.

Health factors associated with development and severity of post-stroke dysphagia: an epidemiological investigation

Background and Purpose

Dysphagia is a common post-stroke occurrence and has been shown to impact patients' morbidity and mortality. The purpose of this study was to use a large population-based dataset to determine specific epidemiological and patient health risk factors that impact development and severity of dysphagia after acute stroke.

Methods

Using data from the Greater Cincinnati Northern Kentucky Stroke Study, GCNKSS, involving a representative sample of approximately 1.3 million people from Southwest Ohio and Northern Kentucky of adults (age ≥18), ischemic and hemorrhagic stroke cases from 2010 and 2015 were identified via chart review. Dysphagia status was determined based on bedside and clinical assessments, and severity by necessity for alternative access to nutrition via nasogastric (NG) or percutaneous endoscopic gastrostomy (PEG) tube placement. Comparisons between patients with and without dysphagia were made to determine differences in baseline characteristics and pre-morbid conditions. Multivariable logistic regression was used to determine factors associated with increased risk of developing dysphagia.

Results

Dysphagia status was ascertained from 4139 cases (1709 with dysphagia). Logistic regression showed: increased age, Black race, higher NIHSS score at admission, having a hemorrhagic stroke (vs infarct), and right hemispheric stroke increased risk of developing dysphagia after stroke. Factors associated with reduced risk included history of high cholesterol, lower pre-stroke mRS score, and white matter disease.

Conclusions

This study replicated many previous findings of variables associated with dysphagia (older age, worse stroke, right sided hemorrhagic lesions), while other variables identified were without clear biological rationale (e.g. Black race, history of high cholesterol and presence of white matter disease). These factors should be investigated in future, prospective studies to determine biological relevance and potential influence in stroke recovery.

Delays in presentation and mortality among Black patients with mechanical thrombectomy after large-vessel stroke at a US hospital

OBJECTIVE

The incidence and severity of stroke are disproportionately greater among Black patients. In this study, the authors sought to examine clinical outcomes among Black versus White patients after mechanical thrombectomy for stroke at a single US institution.

METHODS

All patients who underwent mechanical thrombectomy at a single center from January 1, 2014, through March 31, 2020, were retrospectively analyzed. Patients were grouped based on race, and demographic characteristics, preexisting conditions, clinical presentation, treatment, and stroke outcomes were compared. The association of race with mortality was analyzed in multivariable logistic regression analysis adjusted for potential confounders.

RESULTS

In total, 401 patients (233 males) with a reported race of Black (n = 28) or White (n = 373) underwent mechanical thrombectomy during the study period. Tobacco use was more prevalent among Black patients (43% vs 24%, p = 0.04), but there were no significant differences between the groups with respect to insurance, coronary artery disease, diabetes, illicit drug use, hypertension, or hyperlipidemia. The mean time from stroke onset to hospital presentation was significantly greater among Black patients (604.6 vs 333.4 minutes) (p = 0.007). There were no differences in fluoroscopy time, procedural success (Thrombolysis in Cerebral Infarction grade 2b or 3), hospital length of stay, or prevalence of hemicraniectomy. In multivariable analysis, Black race was strongly associated with higher mortality (32.1% vs 14.5%, p = 0.01). The disparity in mortality rates resolved after adjusting for the average time from stroke onset to presentation (p = 0.14).

CONCLUSIONS

Black race was associated with an increased risk of death after mechanical thrombectomy for stroke. The increased risk may be associated with access-related factors, including delayed presentation to stroke centers.

Tale of 2 Health-care Systems: Disparities in Demographic and Clinical Characteristics between 2 Ischemic Stroke Populations in Los Angeles County

BACKGROUND

Individuals who present to the emergency departments of safety-net systems often have poorly controlled risk factors due to lack of primary care. Little is known about potential differences in presenting characteristics, discharge medications, and discharge destinations of patients with acute ischemic stroke (AIS) who present to safety-net settings versus university medical centers (UMCs).

METHODS

Demographic characteristics, medical history, premorbid medication use, stroke severity, discharge medications, and discharge destination were assessed among consecutive admissions for AIS over a 2-year period at a UMC (n = 385) versus 2 university-affiliated safety-net hospitals (SNHs) (n = 346) in Los Angeles County.

RESULTS

Compared with patients presenting to the UMC, individuals admitted to the SNHs were younger, more frequently male, nonwhite, current smokers, hypertensive, and diabetic; they were less likely to take antithrombotics and statins before admission, and had worse serum lipid and glycemic markers (all P < .05). Patients admitted to the UMC trended toward more cardioembolic strokes and had higher stroke severity scores (P < .0001). At discharge, patients admitted to the SNHs were more likely to receive antihypertensive medications than do patients admitted to the UMC (P < .001), but there were no differences in prescription of antiplatelet medications or statins.

CONCLUSIONS

Individuals with AIS admitted to SNHs in Los Angeles County are younger and have poorer vascular risk factor control than their counterparts at a UMC. Discharge treatment does not vary considerably between systems. Early and more vigorous efforts at primary vascular risk reduction among patients seen at SNHs may be warranted to reduce disparities.

Cell-based therapy for acute organ injury: preclinical evidence and ongoing clinical trials using mesenchymal stem cells

Critically ill patients often suffer from multiple organ failures involving lung, kidney, liver, or brain. Genomic, proteomic, and metabolomic approaches highlight common injury mechanisms leading to acute organ failure. This underlines the need to focus on therapeutic strategies affecting multiple injury pathways. The use of adult stem cells such as mesenchymal stem or stromal cells (MSC) may represent a promising new therapeutic approach as increasing evidence shows that MSC can exert protective effects following injury through the release of promitotic, antiapoptotic, antiinflammatory, and immunomodulatory soluble factors. Furthermore, they can mitigate metabolomic and oxidative stress imbalance. In this work, the authors review the biological capabilities of MSC and the results of clinical trials using MSC as therapy in acute organ injuries. Although preliminary results are encouraging, more studies concerning safety and efficacy of MSC therapy are needed to determine their optimal clinical use. (ANESTHESIOLOGY 2014; 121:1099-121).

Low serum BDNF may indicate the development of PSD in patients with acute ischemic stroke

OBJECTIVE

This study was to test whether serum BDNF or tissue plasminogen activator (tPA) is correlated with the development of depression at the acute stage of stroke.

METHODS

Hundred ischemic stroke patients admitted to the hospital within the first 24 h of stroke onset were consecutively recruited and followed up for 14 days. The 17-item HDRS and MADRS were used to assess the severity of major depressive symptoms on day 3, day 7, and day 14 after admission. The diagnoses of depression were made in accordance with DSM-IV criteria for post-stroke depression (PSD). Serum BDNF and tPA of all the patients were determined by ELISA both on day 1 and day 7 after admission. Meanwhile, 50 healthy control subjects were also recruited and underwent measurement of serum BDNF and tPA once.

RESULTS

We found that 37 patients (37.0%) were diagnosed of major depression at the end of the follow-up. Serum BDNF on day 1 was significantly higher in non-PSD stroke patients than in normal controls, while PSD patients had significantly lower BDNF than non-PSD patients. There was a significant negative correlation between serum BDNF and tPA on day 1 only in PSD patients (r = -0.440, p = 0.006). Serum BDNF < 5.86 ng/ml on day 1 was independently associated with incident PSD at the acute stage of stroke (OR = 28.992; 95% CI, 8.014-104.891; p < 0.001 after adjustment).

CONCLUSION

There was a significant elevation of BDNF early after ischemic stroke. Serum BDNF on day 1 after admission may predict the risk of subsequent PSD. Moreover, tPA may be involved in the change of BDNF.

Amine-modified single-walled carbon nanotubes protect neurons from injury in a rat stroke model

Stroke results in the disruption of tissue architecture and is the third leading cause of death in the United States. Transplanting scaffolds containing stem cells into the injured areas of the brain has been proposed as a treatment strategy, and carbon nanotubes show promise in this regard, with positive outcomes when used as scaffolds in neural cells and brain tissues. Here, we show that pretreating rats with amine-modified single-walled carbon nanotubes can protect neurons and enhance the recovery of behavioural functions in rats with induced stroke. Treated rats showed less tissue damage than controls and took longer to fall from a rotating rod, suggesting better motor functions after injury. Low levels of apoptotic, angiogenic and inflammation markers indicated that amine-modified single-walled carbon nanotubes protected the brains of treated rats from ischaemic injury.

The use of narratives to identify characteristics leading to a productive life following acquired brain injury

PURPOSE

To determine the factors leading to successful recovery and productive lifestyles after acquired brain injury (ABI).

METHOD

Qualitative investigation examined semistructured interviews of 31 survivors of ABI. Thematic analysis followed a phenomenological approach and revealed 4 major themes and 28 subthemes in the interviews. Four participants stood out as exemplars of the themes embodied by all the participants in this investigation. Quotes from each are used to highlight the prevailing themes.

RESULTS

The following 4 major themes emerged from the interviews: development of social support networks, grief and coping strategies, acceptance of the injury and redefinition of self, and empowerment.

CONCLUSIONS

The issues raised in these interviews may serve to inspire other survivors and provide them with hope and motivation as they progress through the recovery process. Suggestions on how clinicians can help to facilitate this process are discussed.

Stem cells for ischemic brain injury: a critical review

No effective therapy is currently available to promote recovery following ischemic stroke. Stem cells have been proposed as a potential source of new cells to replace those lost due to central nervous system injury, as well as a source of trophic molecules to minimize damage and promote recovery. We undertook a detailed review of data from recent basic science and preclinical studies to investigate the potential application of endogenous and exogenous stem cell therapies for treatment of cerebral ischemia. To date, spontaneous endogenous neurogenesis has been observed in response to ischemic injury, and can be enhanced via infusion of appropriate cytokines. Exogenous stem cells from multiple sources can generate neural cells that survive and form synaptic connections after transplantation in the stroke-injured brain. Stem cells from multiple sources cells also exhibit neuroprotective properties that may ameliorate stroke deficits. In many cases, functional benefits observed are likely independent of neural differentiation, although the exact mechanisms remain poorly understood. Future studies of neuroregeneration will require the demonstration of function in endogenously born neurons following focal ischemia. Further, methods are currently lacking to demonstrate definitively the therapeutic effect of newly introduced neural cells. Increased plasticity following stroke may facilitate the functional integration of new neurons, but the loss of appropriate guidance cues and supporting architecture in the infarct cavity will likely impede the restoration of lost circuitry. Thus careful investigation of the mechanisms underlying trophic benefits will be essential. Evidence to date suggests that continued development of stem cell therapies may ultimately lead to viable treatment options for ischemic brain injury.

An analysis of methylenetetrahydrofolate reductase and glutathione S-transferase omega-1 genes as modifiers of the cerebral response to ischemia

Background

Cerebral ischemia involves a series of reactions which ultimately influence the final volume of a brain infarction. We hypothesize that polymorphisms in genes encoding proteins involved in these reactions could act as modifiers of the cerebral response to ischemia and impact the resultant stroke volume. The final volume of a cerebral infarct is important as it correlates with the morbidity and mortality associated with non-lacunar ischemic strokes.

Methods

The proteins encoded by the methylenetetrahydrofolate reductase (MTHFR) and glutathione S-transferase omega-1 (GSTO-1) genes are, through oxidative mechanisms, key participants in the cerebral response to ischemia. On the basis of these biological activities, they were selected as candidate genes for further investigation. We analyzed the C677T polymorphism in the MTHFR gene and the C419A polymorphism in the GSTO-1 gene in 128 patients with non-lacunar ischemic strokes.

Results

We found no significant association of either the MTHFR (p = 0.72) or GSTO-1 (p = 0.58) polymorphisms with cerebral infarct volume.

Conclusion

Our study shows no major gene effect of either the MTHFR or GSTO-1 genes as a modifier of ischemic stroke volume. However, given the relatively small sample size, a minor gene effect is not excluded by this investigation.

Acute but not chronic differences in skilled reaching for food following motor cortex devascularization vs. photothrombotic stroke in the rat

The variability in the behavioral outcome of human and nonhuman animals after stroke raises the question whether the way that a stroke occurs is a contributing factor. Photothrombotic stroke in rats has been reported to produce especially variable results, with some animals showing either slight to no impairment to other animals displaying severe impairments. The present study investigated this variability. Rats received three different-sized photothrombotic treatments and were contrasted to rats receiving a "standard" motor cortex stroke produced by pial stripping. Rats were assessed acutely and chronically on a skilled reaching for food task using end-point measures and movement assessment in a constraint-induced rehabilitation paradigm. The results indicated that as the size of the photothrombotic infarct approached the size of the pial strip infarct so did chronic behavioral deficits. Nevertheless there were differences in the time course of recovery. Rats with photothrombotic lesions of all sizes were less impaired in the acute period of recovery both on measures of learned nonuse and constrained-induced recovery. The findings are discussed in relation to the idea that whereas the course of recovery might be altered as a function of the type of stroke, chronic deficits are more closely related to the ensuing damage.

Poststroke cerebral peduncular atrophy correlates with a measure of corticospinal tract injury in the cerebral hemisphere

BACKGROUND AND PURPOSE

Methods have not been well developed and tested to predict the extent of remote degeneration in the central nervous system that follows cerebral infarction. We hypothesized that the extent of infarction overlap with the cerebral hemispheric course of the corticospinal tract (CST) on structural MR imaging predicts the extent of ipsilateral cerebral peduncular atrophy in patients with chronic stroke.

MATERIALS AND METHODS

Hemiparetic patients (n = 34) with supratentorial unilateral infarctions who were at least 1 year poststroke onset and enrolled in research protocols of Constraint-Induced Movement therapy underwent volumetric T1 MR imaging of the brain. The following measures were calculated for each patient: 1) the maximal proportion of the CST in the cerebral hemisphere on axial section that was overlapped by infarction, 2) total infarction volume, and 3) the ratio of the cross-sectional area of the ipsilateral cerebral peduncle to the area of the contralateral cerebral peduncle (peduncular asymmetry ratio). Correlation analyses evaluated the predictive value of CST injury or infarction volume for the peduncular asymmetry ratio.

RESULTS

CST injury correlated significantly with the peduncular asymmetry ratio (r = -0.65; P < .001), whereas infarction volume did not (r = -0.31; P = .09).

CONCLUSIONS

The extent of postinfarction CST injury in the cerebral hemisphere predicts the extent of ipsilateral cerebral peduncular atrophy. More generally, the findings suggest that the extent of remote wallerian degeneration of a fiber tract is strongly related to its extent of injury directly at the site of infarction.

Analysis of the XRCC1 gene as a modifier of the cerebral response in ischemic stroke

Background

Although there have been studies of the genetic risk factors in the development of stroke, there have been few investigations of role of genes in the cerebral response to ischemia. The brain responds to ischemia in a series of reactions that ultimately influence the volume of a stroke that, in general, correlates with disability. We hypothesize that polymorphisms in genes encoding proteins involved in these reactions could act as modifiers of this response and impact stroke volume. One of the pathways participating in the cerebral ischemic response involves reactive oxygen species which can cause oxidative damage to nucleic acids. DNA repair mechanisms are in place to protect against such damage and imply a role for DNA repair genes in the response of the brain to ischemia and are potential candidate genes for further investigation.

Methods

We studied two common polymorphisms in the DNA repair gene, XRCC1, C26304T and G28152A, in 134 well characterized patients with non lacunar ischemic strokes. We also performed a case control association study with 113 control patients to assess whether these variants represent risk factors in the development of ischemic stroke.

Results

Independent of etiology, the "T" allele of the C26304T polymorphism is significantly associated with larger stroke volumes (T-test analysis, p < 0.044; multivariate regression analysis, β = 0.23, p < 0.008). In the case control association study, we found that neither of these polymorphisms represented a risk factor for the development of stroke.

Conclusion

Our study suggests a major gene effect of the "T" allele of the C26304T polymorphism modulating the cerebral response to ischemia in non lacunar ischemic stroke.

Analysis of the Endothelial Nitric Oxide Synthase Gene as a Modifier of the Cerebral Response to Ischemia

We studied the endothelial nitric oxide synthase (eNOS or NOS-3) gene as a potential modifier of the cerebral response to ischemia by investigating the association of two common polymorphisms with ischemic stroke volume. We genotyped an intronic variable number tandem repeat and a single nucleotide polymorphism, G894T, in 132 patients with nonlacunar ischemic strokes in whom clinical data and stroke lesion volume were recorded. Our results show that all genotypes are in Hardy-Weinberg equilibrium. After adjustment of covariates, neither of the NOS-3 polymorphisms showed significant differences comparing the genotypes and mean stroke volume (analysis of variance). Our results do not suggest a major gene effect of the NOS-3 gene as a modifier of the cerebral response to ischemia.

Rodent models of focal stroke: size, mechanism, and purpose

Rodent stroke models provide the experimental backbone for the in vivo determination of the mechanisms of cell death and neural repair, and for the initial testing of neuroprotective compounds. Less than 10 rodent models of focal stroke are routinely used in experimental study. These vary widely in their ability to model the human disease, and in their application to the study of cell death or neural repair. Many rodent focal stroke models produce large infarcts that more closely resemble malignant and fatal human infarction than the average sized human stroke. This review focuses on the mechanisms of ischemic damage in rat and mouse stroke models, the relative size of stroke generated in each model, and the purpose with which focal stroke models are applied to the study of ischemic cell death and to neural repair after stroke.

Different MRI findings for normal elderly and very mild Alzheimer's disease in a community: Implications for clinical practice

To investigate magnetic resonance imaging (MRI) findings of very mild dementia, 485 participants were randomly selected in a community. Three hundred and forty participants were of Clinical Dementia Rating (CDR) 0 (healthy), 113 were of CDR 0.5 (questionable dementia), and 32 were of CDR 1 and 2 (including 20 Alzheimer's disease, AD). Cortical atrophy, white matter lesion, etc., were visually assessed. We found that each part of the brain showed atrophy in older adults for CDR 0. For CDR 0.5, the relationships between MRI findings and age were weaker, and for AD, there were no such relationship. Atrophy related with dementia severity was found to be limited to the lateral and medial temporal lobes. For CDR 0.5, amygdala atrophy was the only finding indicating CDR effect but no age effect. The amygdala or anterior entorhinal atrophy is important for discriminating very mild dementia from normal elderly.

Intrinsic factors influencing post stroke brain reorganization

Reorganization of the brain, specifically the motor cortex surrounding the stroke, accounts for much of the observed neurological recovery following stroke. Not surprisingly, size of the stroke lesion has the greatest impact on neurological recovery in both animal and clinical research studies. Spontaneous recovery of lost function is possible after a cortical lesion, particularly if the lesion is small. Age correlates negatively with recovery; older individuals generally demonstrate slower and less complete recovery. However, age by itself is a poor predictor of functional recovery.

Applying the transtheoretical model to the exercise behaviors of stroke patients

Individuals with disabilities, including stroke, are frequently deconditioned. A variety of factors, including infrequent exercise participation, may be responsible for the deconditioning observed. According to the transtheoretical model (TTM), individuals progress through cognitive processes, termed stages, that indicate their readiness to undertake a particular healthy behavior, such as exercise. Our study examined 178 community-dwelling stroke patients' readiness to initiate an exercise program and their current exercise patterns. Using the Stages of Change Questionnaire, we found over 75% of respondents to be in the exercise preadoption stages of precontemplation, contemplation, or preparation. Moreover, participants classified in the postadoption stages of maintenance and action reported exercising significantly more than those in the preadoption stages. Individuals in the postadoption stages were also participating in significantly more sessions of strenuous or moderate exercise than those in the preadoption stages. It was concluded that the TTM is a valid theoretical framework to measure stroke patients' readiness to participate in exercise. However, additional research examining the psychosocial and functional factors mitigating these attitudes, and the stability of these attitudes, needs to be performed.

Treatable Potential Cardiac Sources of Embolism in Patients with Cerebral Ischemic Events: A Selective Transesophageal Echocardiographic Study

OBJECTIVES

To characterize cardiac sources of emboli detected by transesophageal echocardiography (TEE) in patients without recognizable cause of transient ischemic attack (TIA) and/or ischemic stroke and TIA.

METHODS

We examined a prospective registry that included all patients with TIA and/or stroke evaluated by TEE between July 2000 and August 2001 at our medical center. Ischemic events were classified according to clinical and neuroimaging findings as cortical, lacunar, or vertebrobasilar circulation. Demographic, clinical, neuroimaging, and echocardiographic characteristics were studied.

RESULTS

TEE was performed in 237 patients without recognized cause of TIA and/or stroke, of which 105 (44%) events were cortical, 35 (15%) were lacunar, 32 (14%) were vertebrobasilar, and 65 (27%) were in multiple distributions. Mean age of patients was 59 +/- 14 years (range, 21 to 93 years); 119 (51%) were men. Potential treatable cardioembolic sources were detected in 146 (61%) patients: patent foramen ovale with right-to-left shunt (n = 59), left atrial clot (n = 6), left atrial appendage clot (n = 8), and severe thoracic aortic atherosclerotic plaque disease (plaque thickness >4 mm) (n = 79 patients [33%], 56 had an ulcerated plaque and 4 had mobile plaque). Patient age and topography of the ischemic event did not correlate with TEE-defined cardioembolic sources.

CONCLUSIONS

TEE identified high frequencies of potential treatable cardioembolic sources in patients with ischemic events. TEE should be considered in all patients who do not have identified cause of TIA and/or stroke for early treatment and prevention of recurrent events.

Long-lasting functional disabilities in middle-aged rats with small cerebral infarcts

Recommendations from experts and recently established guidelines on how to improve the face and predictive validity of animal models of stroke have stressed the importance of using older animals and long-term behavioral-functional endpoints rather than relying almost exclusively on acute measures of infarct volume in young animals. The objective of the present study was to determine whether we could produce occlusions in older rats with an acceptable mortality rate and then detect reliable, long-lasting functional deficits. A reversible intraluminar suture middle cerebral artery occlusion (MCAO) procedure was used to produce small infarcts in middle-aged rats. This resulted in an acceptable mortality rate, and robust disabilities were detected in functional assays, although the degree of total tissue loss measured 90 d after MCAO was quite modest. Infarcted animals were functionally impaired relative to sham control animals even 90 d after the occlusions, and when animals were subgrouped based on amount of tissue loss, MCAO animals with only 4% tissue loss exhibited enduring neurological-behavioral impairments relative to sham-operated controls, and the functional impairments in the group with the largest infarcts (20% tissue loss) were more severe than the functional impairments in the rats with 4% tissue loss. These results suggest that this model, using reversible MCAO to produce small infarcts and long-lasting functional-behavioral deficits in older rats, may represent an advance in the relatively higher-throughput modeling of stroke and its recovery in rodents and may be useful in the development and characterization of future stroke therapies.

Tissue microenvironments within functional cortical subdivisions adjacent to focal stroke

Stroke produces a region of complete cell death and areas of partial damage, injury, and gliosis. The spatial relationship of these regions of damage to the infarct core and within spared neuronal circuits has not been identified. A model of cortical stroke was developed within functional subsets of the somatosensory cortex. Infarct size, regions of apoptosis, oxidative DNA damage, heat shock protein induction, and subtypes of reactive gliosis were precisely mapped with the somatosensory body map, quantified, and interrelated. Three tissue microenvironments were recognized: zones of partial ischemic damage, heat shock protein induction, and distributed gliosis. These three zones involved progressively more distant cortical regions, each larger than the infarct core. The zone of partial ischemic damage represents an overlap region of apoptotic cell death, oxidative DNA damage, loss of synaptic connections, and local reactive gliosis. The zone of distributed gliosis occupies distinct functional areas of the somatosensory cortex. The tissue reorganization induced by stroke is much larger than the stroke site itself. Adjacent tissue microenvironments are sites of distinct reactive cellular signaling and may serve as a link between the processes of acute cell death and delayed neuronal plasticity after focal stroke.

Relative cerebral blood volume measurements in intracranial mass lesions: interobserver and intraobserver reproducibility study

PURPOSE

To assess inter- and intraobserver reproducibility for different techniques of measuring relative cerebral blood volume (rCBV) in patients with intracranial mass lesions.

MATERIALS AND METHODS

Three independent observers (neuroradiology fellows) who were blinded to the histopathologic diagnosis performed rCBV measurements in 50 patients with various intracranial mass lesions. Three different methods were compared. With method 1, placement of a single region of interest was guided by a color overlay map. With methods 2 and 3, the highest rCBV value and the mean of repeated rCBV measurements, respectively, were recorded. Calculations of the intraclass correlation coefficient, coefficient of variation (CV), and descriptive statistics were used to determine the levels of reproducibility. A multiple linear regression model was used to evaluate for possible explanatory factors for interobserver variance.

RESULTS

Method 2 had, overall, the best reproducibility of all techniques, with an intraclass interobserver correlation coefficient of 0.71 (indicating good agreement), interobserver CV of 30%, and intraobserver CV in the range of 32%-41%. Measurement variations between observers correlated significantly (P <.001) with increasing rCBV values.

CONCLUSION

In this study, interobserver and intraobserver reproducibility of rCBV measurements were clinically acceptable.