Acute blood glucose level and outcome from ischemic stroke. Trial of ORG 10172 in Acute Stroke Treatment (TOAST) Investigators

Adaptive cerebral neovascularization in a model of type 2 diabetes: relevance to focal cerebral ischemia

OBJECTIVE

The effect of diabetes on neovascularization varies between different organ systems. While excessive angiogenesis complicates diabetic retinopathy, impaired neovascularization contributes to coronary and peripheral complications of diabetes. However, how diabetes influences cerebral neovascularization is not clear. Our aim was to determine diabetes-mediated changes in the cerebrovasculature and its impact on the short-term outcome of cerebral ischemia.

RESEARCH DESIGN AND METHODS

Angiogenesis (capillary density) and arteriogenesis (number of collaterals and intratree anostomoses) were determined as indexes of neovascularization in the brain of control and type 2 diabetic Goto-Kakizaki (GK) rats. The infarct volume, edema, hemorrhagic transformation, and short-term neurological outcome were assessed after permanent middle-cerebral artery occlusion (MCAO).

RESULTS

The number of collaterals between middle and anterior cerebral arteries, the anastomoses within middle-cerebral artery trees, the vessel density, and the level of brain-derived neurotrophic factor were increased in diabetes. Cerebrovascular permeability, matrix metalloproteinase (MMP)-9 protein level, and total MMP activity were augmented while occludin was decreased in isolated cerebrovessels of the GK group. Following permanent MCAO, infarct size was smaller, edema was greater, and there was no macroscopic hemorrhagic transformation in GK rats.

CONCLUSIONS

The augmented neovascularization in the GK model includes both angiogenesis and arteriogenesis. While adaptive arteriogenesis of the pial vessels and angiogenesis at the capillary level may contribute to smaller infarction, changes in the tight junction proteins may lead to the greater edema following cerebral ischemia in diabetes.

Aggressive glucose control for acute ischemic stroke patients by insulin infusion

BACKGROUND AND PURPOSE

Hyperglycemia after acute ischemic stroke (AIS) is associated with poor outcomes. However, there is no consensus as to the optimal method for glycemic control. We designed an insulin infusion protocol for aggressive glucose control and investigated its efficacy and safety.

METHODS

We applied our protocol to patients within 48 hours after AIS or transient ischemic attack (TIA) with an initial capillary glucose level of between 100 and 399 mg/dL (5.6-22.2 mmol/L). An insulin solution comprising 40 or 50 U of human regular insulin in 500 mL of 5% dextrose was administered for 24 hours. Capillary glucose was measured every 2 hours and the infusion rate was adjusted according to a nomogram with a target range of 80-129 mg/dL (4.4-7.2 mmol/L). Changes in glucose and overall glucose levels during insulin infusion were analyzed according to the presence of diabetes or admission hyperglycemia (admission glucose >139 mg/dL or 7.7 mmol/L) by the generalized estimating equation method.

RESULTS

The study cohort comprised 115 consecutive patients. Glucose was significantly lowered from 160+/-57 mg/dL (8.9+/-3.2 mmol/L) at admission to 93+/-28 mg/dL (5.2+/-1.6 mmol/L) during insulin infusion (p<0.05). Laboratory hypoglycemia (capillary glucose <80 mg/dL or 4.4 mmol/L) occurred in 91 (71%) patients, 11 (10%) of whom had symptomatic hypoglycemia. Although glucose levels were significantly lowered and maintained within the target range in all patients, overall glucose levels were significantly higher in patients with diabetes or hyperglycemia (p<0.05).

CONCLUSIONS

Our insulin-infusion protocol was effective in glycemic control for patients with AIS or TIA. Further modification is needed to improve the efficacy and safety of this procedure, and tailored intervention should be considered according to glycemic status.

Glucose level and brain infarction: a prospective case-control study and prospective study

BACKGROUND

Hyperglycaemia in the acute phase of stroke has been established as a predictor of higher mortality. But recent data regarding active treatment of hyperglycaemia showed no clinical benefit suggesting that hyperglycaemia may not have a detrimental effect in brain infarction. Additional data are needed to resolve this uncertainty and identify patients at higher risk if any.

METHODS

A total of 477 adult Caucasian patients with brain infarction and 395 age- and sex-matched controls admitted at the same centres for nonneurological causes were recruited consecutively from 12 neurological centres in France. Electrocardiographic, carotid ultrasonography, and transcranial Doppler studies were performed. Blood was drawn in the morning from fasting subjects for glucose measurement. Functional outcome was measured on admission, at 10 days and at 6 months after the onset of stroke using the modified Rankin scale.

RESULTS

Among 477 brain infarction patients and 395 hospitalised controls the adjusted mean (+/-SEM) glucose level was higher in cases (6.4+/-1.0 mmol/l) than in controls (6.0+/-1.01 mmol/l, P=0.006), with a significant heterogeneity across sexes. The fully adjusted odds ratio of brain infarction per 1-standard deviation increase in log-glucose level was 1.02 (95% confidence interval, 0.77-1.37) in men and 2.21 (95% confidence interval, 1.44-3.40) in women. Among the 477 brain infarction cases elevated admission glucose levels were associated with poor outcomes and higher poststroke mortality after adjustment for conventional vascular risk factors and infarct volume. These relationships were not modified by sex.

CONCLUSIONS

Elevated admission glucose levels were associated with brain infarction in women only and with a higher 5-year mortality. Further investigation focusing on the impact of glucose level in different target population is needed to optimise glycaemic management in acute brain infarction patients.

Efficiency and safety of a standardized protocol for intravenous insulin therapy in ICU patients with neurovascular or head injury

BACKGROUND

To evaluate the safety and efficiency of a protocol for glycemic control in intensive care unit (ICU) patients with neurovascular or head injury.

METHODS

Two cohorts of 50 consecutive patients admitted to the ICU with an admission diagnosis of neurovascular or head injury before and after protocol implementation were evaluated. All patients in the interventional cohort received insulin using a standardized intravenous insulin infusion protocol targeting blood glucose levels of 7-9 mmol/l. Efficiency (time to reach and time within target range), safety (hypoglycemia), and nursing compliance (protocol violations) were evaluated.

RESULTS

The median time to reach the target blood glucose range was shorter in the interventional cohort than the conventional cohort (5.0 h [0.5-20.5 h] vs. 12.9 h [1.3-90.3 h]; P < 0.001). More time was spent within target range in the interventional cohort than in the conventional cohort (36.4 +/- 16.3% vs. 27.1 +/- 19.0%; P < 0.001). The median prevalence of mild (<4.9 mmol/l) hypoglycemia (0 [0-1.11]% vs. 0.58 [0-2.79]%; P < 0.001) and moderate (<3.9) hypoglycemia (0[0-0.55]% vs. 0 [1-1.25]%; p < 0.001) was significantly lower in the interventional cohort.

CONCLUSIONS

The intravenous insulin infusion protocol improved the safety and efficiency of glycemic control for ICU patients with neurovascular or head injury.

Blood glucose in acute stroke

Blood glucose is often elevated in acute stroke, and higher admission glucose levels are associated with larger lesions, greater mortality and poorer functional outcome. In patients treated with thrombolysis, hyperglycemia is associated with an increased risk of hemorrhagic transformation of infarcts. For a number of years, tight glycemic control has been regarded as beneficial in critically illness, but recent research has been unable to support this notion. The only completed randomized study on glucose-lowering therapy in stroke has failed to demonstrate effect, and concerns relating to the risk of inducing potentially harmful hypoglycemia has been raised. Still, basic and observational research is overwhelmingly in support of a causal relationship between blood glucose and stroke outcome and further research on glucose-lowering therapy in acute stroke is highly warranted.

Hyperglycemia in bacterial meningitis: a prospective cohort study

Background

Hyperglycemia has been associated with unfavorable outcome in several disorders, but few data are available in bacterial meningitis. We assessed the incidence and significance of hyperglycemia in adults with bacterial meningitis.

Methods

We collected data prospectively between October 1998 and April 2002, on 696 episodes of community-acquired bacterial meningitis, confirmed by culture of CSF in patients >16 years. Patients were dichotomized according to blood glucose level on admission. A cutoff random non-fasting blood glucose level of 7.8 mmol/L (140 mg/dL) was used to define hyperglycemia, and a cutoff random non-fasting blood glucose level of 11.1 mmol/L (200 mg/dL) was used to define severe hyperglycemia. Unfavorable outcome was defined on the Glasgow outcome scale as a score <5. We also evaluated characteristics of patients with a preadmission diagnosis of diabetes mellitus.

Results

69% of patients were hyperglycemic and 25% severely hyperglycemic on admission. Compared with non-hyperglycemic patients, hyperglycemia was related with advanced age (median, 55 yrs vs. 44 yrs, P < 0.0001), preadmission diagnosis of diabetes (9% vs. 3%, P = 0.005), and distant focus of infection (37% vs. 28%, P = 0.02). They were more often admitted in coma (16% vs. 8%; P = 0.004) and with pneumococcal meningitis (55% vs. 42%, P = 0.007). These differences remained significant after exclusion of patients with known diabetes. Hyperglycemia was related with unfavorable outcome in a univariate analysis but this relation did not remain robust in a multivariate analysis. Factors predictive for neurologic compromise were related with higher blood glucose levels, whereas factors predictive for systemic compromise were related with lower blood glucose levels. Only a minority of severely hyperglycemic patients were known diabetics (19%). The vast majority of these known diabetic patients had meningitis due to Streptococcus pneumoniae (67%) or Listeria monocytogenes (13%) and they were at high risk for unfavorable outcome (52%).

Conclusion

The majority of patients with bacterial meningitis have hyperglycemic blood glucose levels on admission. Hyperglycemia can be explained by a physical stress reaction, the central nervous system insult leading to disturbed blood-glucose regulation mechanisms, and preponderance of diabetics for pneumococcal meningitis. Patients with diabetes and bacterial meningitis are at high risk for unfavorable outcome.

Glycemic control and the injured brain

The interaction between glycemic control and critical neurologic illness and injury is complex. Hyperglycemia can be either the cause or the result of severe brain injury. Hyperglycemia in acute neurologic injury is associated with worse neurologic outcomes. Demographic patterns, including an aging population and shifts in racial and ethnic representation, contribute to the increasing prevalence of hyperglycemia and diabetes among victims of the most common neurologic emergencies. This article reviews the epidemiology of the problem, relevant pathophysiology, the use of tight glycemic control therapy in other populations, and the potential for tight glycemic control as a way to improve outcomes after acute neurologic illness and injury.

Effective glycemic control with aggressive hyperglycemia management is associated with improved outcome in aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Hyperglycemia strongly predicts poor outcome in patients with aneurysmal subarachnoid hemorrhage, but the effect of hyperglycemia management on outcome is unclear. We studied the impact of glycemic control on outcome of patients with aneurysmal subarachnoid hemorrhage.

METHODS

A prospective intensive care unit database was used to identify 332 patients with hyperglycemic aneurysmal subarachnoid hemorrhage admitted between January 2000 and December 2006. Patients treated with an aggressive hyperglycemia management (AHM) protocol after 2003 (N=166) were compared with 166 patients treated using a standard hyperglycemia management before 2003. Within the AHM group, outcome was compared between patients who achieved good (mean glucose burden <1.1 mmol/L) and poor (mean glucose burden >or=1.1 mmol/L) glycemic control. Poor outcome was defined as modified Rankin scale >or=4 at 3 to 6 months. Multivariable logistic regression models correcting for temporal trend were used to quantify the effect of AHM on poor outcome.

RESULTS

Poor outcome in AHM-treated patients was lower (28.31% versus 40.36%) but was not statistically significant after correcting for temporal trend. However, good glycemic control significantly reduced the incidence of poor outcome (OR, 0.25; 95% CI, 0.08 to 0.80; P=0.02) compared with patients with poor glycemic control within the AHM group. No difference in the rate of clinical vasospasm or the development of delayed ischemic neurological deficit was seen before and after AHM protocol implementation.

CONCLUSIONS

AHM results in good glucose control and significantly reduces the odds for poor outcome after aneurysmal subarachnoid hemorrhage in glucose-controlled patients. Further studies are needed to confirm these results.

Hyperglycemia, diabetes and stroke: focus on the cerebrovasculature

Acute ischemic stroke (AIS) results from the occlusion of an artery and causes vascular and neuronal damage, both of which affect the extent of ischemic injury and stroke outcome. Despite extensive efforts, there is only one effective treatment for AIS. Given that up to 40% of the AIS patients present with admission hyperglycemia either as a result of diabetes or acute stress response, targets for neuronal and vascular protection under hyperglycemic conditions need to be better defined. Here, we review the impact of diabetes and acute hyperglycemia on experimental stroke with an emphasis on cerebrovasculature structure and function. The relevance to clinical evidence is also discussed.

Glucose and NADPH oxidase drive neuronal superoxide formation in stroke

OBJECTIVE

Hyperglycemia has been recognized for decades to be an exacerbating factor in ischemic stroke, but the mechanism of this effect remains unresolved. Here, we evaluated superoxide production by neuronal nicotinamide adenine dinucleotide phosphate (NADPH) oxidase as a possible link between glucose metabolism and neuronal death in ischemia-reperfusion.

METHODS

Superoxide production was measured by the ethidium method in cultured neurons treated with oxygen-glucose deprivation and in mice treated with forebrain ischemia-reperfusion. The role of NADPH oxidase was examined using genetic disruption of its p47(phox) subunit and with the pharmacological inhibitor apocynin.

RESULTS

In neuron cultures, postischemic superoxide production and cell death were completely prevented by removing glucose from the medium, by inactivating NADPH oxidase, or by inhibiting the hexose monophosphate shunt that generates NADPH from glucose. In murine stroke, neuronal superoxide production and death were decreased by the glucose antimetabolite 2-deoxyglucose and increased by high blood glucose concentrations. Inactivating NADPH oxidase with either apocynin or deletion of the p47(phox) subunit blocked neuronal superoxide production and negated the deleterious effects of hyperglycemia.

INTERPRETATION

These findings identify glucose as the requisite electron donor for reperfusion-induced neuronal superoxide production and establish a previously unrecognized mechanism by which hyperglycemia can exacerbate ischemic brain injury.

Management of hyperglycemia during acute stroke

Long-term complications of hyperglycemia are well known, but short-term complications are not. Because hyperglycemia and hypoglycemia can be corrected relatively rapidly, it seems important to determine if such interventions during acute illnesses improve patient outcomes. In most animal stroke studies, animals with hyperglycemia before or during brain ischemia have worse outcomes than those with normoglycemia. In humans, hyperglycemia during acute stroke has been associated with worse clinical outcomes than normoglycemia, but it remains to be established if rapid correction of the hyperglycemia will improve patient outcomes. Intravenous insulin infusion protocols are the only currently established methods to effectively lower and control hyperglycemia during acute illness. Recent pilot clinical trials demonstrate feasibility and safety of such interventions. One randomized efficacy trial has been reported and additional trials are needed. In the meantime, an intermediate approach to managing acute stroke hyperglycemia with subcutaneous insulin seems reasonable.

Acute hyperglycemia compromises cerebral blood flow following cortical spreading depression in rats monitored by laser speckle imaging

Hyperglycemia and cortical spreading depression (CSD) are possible factors that worsen the outcome of ischemic stroke, and it is probable that there is a longterm cooperative effect of hyperglycemia and CSD on cerebral blood flow (CBF). Long-lasting and full-field observation of changes in CBF following CSD in vivo during acute hyperglycemia in rats might show whether this is the case. Here, we utilized laser speckle imaging to study influences of acute hyperglycemia on CBF at the level of individual vascular compartments for 3 h in normal rats and those with CSD. It is shown that there are extensive increases of CBF at the arteriole and parenchyma over the normal rat cortex during acute hyperglycemia, whereas there is no significant change in CBF at the venule. We also find that, at all vascular compartments, after the glucose administration there is a stepwise reduction of CBF following CSD, but after saline injection CBF following CSD is close to the baseline. Our results indicate that acute hyperglycemia could aggravate the severity of decrease in CBF following CSD, suggesting possible mechanisms by which hyperglycemia exacerbates cerebral damage after ischemic stroke.

Intensive care unit hypoglycemia predicts depression during early recovery from acute lung injury

OBJECTIVE

To evaluate the association between intensive care unit blood glucose levels and depression after acute lung injury.

DESIGN

Prospective cohort study.

SETTING

Twelve intensive care units in four hospitals in Baltimore, MD.

PATIENTS

Consecutive acute lung injury survivors (n = 104) monitored during 1717 intensive care unit patient-days and screened for depression at 3 months after acute lung injury.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The prevalence of a positive screening test for depression (Hospital Anxiety and Depression subscale score > or = 8) at follow-up was 28%. After adjustment for confounders, patients with a mean daily minimum intensive care unit glucose level < 100 mg/dL had significant increases in mean depression score (2.1 points, 95% confidence interval 0.6-3.7) and in the likelihood of a positive depression screening test (relative risk 2.6, 95% confidence interval 1.2-4.2). Patients with documented hypoglycemia < 60 mg/dL during their intensive care unit stay also had greater symptoms of depression (2.0 points, 95% confidence interval 0.5-3.5; relative risk 3.6, 95% confidence interval 1.8-5.1). Other factors independently associated with a positive depression screening test included body mass index > 40 kg/m2 (relative risk 3.3, 95% confidence interval 1.2-4.2), baseline depression/anxiety (relative risk 3.9, 95% confidence interval 1.5-6.5), and mean daily intensive care unit benzodiazepine dose > 100 mg of midazolam-equivalent agent (relative risk 2.4, 95% confidence interval 1.1-3.8).

CONCLUSIONS

Hypoglycemia in the intensive care unit is associated with an increased risk of positive screening for depression during early recovery from acute lung injury. Baseline depressive symptoms, morbid obesity, and intensive care unit benzodiazepine dose were also associated with postacute lung injury depressive symptoms. These findings warrant increased glucose monitoring for intensive care unit patients at risk for hypoglycemia and further research on how patient and intensive care unit management factors may contribute to postintensive care unit depression.

Dynamic of Hyperglycemia as a Predictor of Stroke Outcome in the ECASS-II Trial

Background and Purpose— Baseline hyperglycemia has been considered an independent predictor of stroke outcome. The present study analyzes the dynamics of serum glucose levels within the first 24 hours and its impact on stroke outcome.

Methods— We studied 748 patients with acute ischemic hemispheric stroke in the second European Cooperative Acute Stroke Study (ECASS-II). The patients had 2 serum glucose measurements, at baseline and at 24 hours. Four dynamic patterns were defined as baseline hyperglycemia present only at baseline, 24-hour hyperglycemia present only at 24 hours, persistent hyperglycemia, ie, hyperglycemia at baseline and at 24 hours, and persistent normoglycemia, ie, normoglycemia at baseline and at 24 hours. The end points were 7-day neurological improvement on National Institutes of Health Stroke Scale, 30-day favorable functional outcome (Barthel Index 95 or 100), 90-day negligible dependence (modified Rankin Scale 0 to 2), all-cause mortality within 90 days, and hemorrhagic transformation on CT within the first 7 days.

Results— In nondiabetic patients, persistent hyperglycemia was inversely associated with neurological improvement (OR=0.31; 95% CI=0.16 to 0.60), 30-day favorable functional outcome (OR=0.27; 95% CI=0.12 to 0.62), and 90-day negligible dependence (OR=0.36; 95% CI=0.17 to 0.73); it was associated with an increased risk of mortality within 90 days (OR=7.61; 95% CI=3.23 to 17.90) and for parenchymal hemorrhage (OR=6.64; 95% CI=2.63 to 16.78), whereas it was inversely associated with hemorrhagic infarction (OR=0.30; 95% CI=0.13 to 0.71). Delayed hyperglycemia at 24 hours was associated with the risks of death (OR=5.99; 95% CI=2.51 to 14.2) and parenchymal hemorrhage (OR=5.69; 95% CI-2.05 to 15.8) and inversely associated with no and negligible dependency (OR=0.40; 95% CI=0.20 to 0.78). Hyperglycemia at baseline only was not associated with any parameter of worse outcome. In patients with diabetes, the dynamic patterns of hyperglycemia did not suggest an association with stroke outcome.

Conclusions— Persistent hyperglycemia was associated with all bad outcome end points studied. In addition to a single glucose measurement, the pattern of change should be considered in the prediction of stroke outcome.

Management of acute ischemic stroke

Stroke is the third leading cause of death and the leading cause of disability in the United States. This article summarizes the management of acute ischemic stroke, including conventional and novel therapies. The article provides an overview of the initial management, diagnostic work-up, treatment options, and supportive measures that need to be considered in the acute phase of ischemic stroke.

Serum calcium as prognosticator in ischemic stroke

BACKGROUND AND PURPOSE

Calcium (Ca(2+)) plays a role in the cellular and molecular pathways of ischemic neuronal death. We evaluated the impact of both early and delayed Ca(2+) levels on clinical outcomes from acute ischemic stroke.

METHODS

The relations between blood calcium level obtained early (<4.5 hours), and delayed (72 to 96 hours) after ischemic stroke onset versus clinical outcomes were analyzed in 826 subjects enrolled in an international trial in the Virtual International Stroke Trials Archive. Subjects were categorized into Ca(2+) quartiles. Outcome measures analyzed included baseline and 72- to 96-hour stroke severity, as well as 3-month functional and global disability scales. The independent effect of calcium on outcome was evaluated by median and logistic regression analysis.

RESULTS

Six hundred and fifty-nine (80%) of the trial subjects had complete baseline data including Ca(2+) levels. Bivariately, the highest delayed Ca(2+) quartile (versus lowest) was associated with lesser stroke severity and better 3-month functional and independence scale outcomes (all P<0.001), but no significant outcome differences were noted among early Ca(2+) levels. In multivariable analysis, delayed Ca(2+) in the highest quartile (versus lowest quartile) was associated with greater 3-month independence score on the Barthel Index scale (76.9 versus 55.4, P=0.006). No other significant outcome differences were noted between highest and lowest quartiles for both early and delayed Ca(2+) quartiles.

CONCLUSIONS

Elevated 72- to 96-hour serum Ca(2+) levels independently predict greater independence 3 months after ischemic stroke, but very early serum Ca(2+) appear not to have any prognostic significance.

Association of serum bilirubin with ischemic stroke outcomes

BACKGROUND

Higher levels of serum bilirubin may offer a therapeutic advantage in oxidative stress-mediated diseases, but may also simply reflect intensity of oxidative stress. Little is known about the role of bilirubin in stroke. We assessed the relation of serum bilirubin levels with clinical presentation and outcomes among patients hospitalized with ischemic stroke.

METHODS

Data were collected prospectively during a 5-year period on consecutive ischemic stroke admissions to a university hospital. Serum bilirubin levels, total (Tbil) and direct (Dbil), were measured on admission. Presenting stroke severity was assessed with the National Institutes of Health Stroke Scale (NIHSS). Functional outcome at discharge was assessed using the modified Rankin scale.

RESULTS

Among 743 patients, mean age was 67.3 years and 47.5% were women. Median presenting NIHSS score was 4, and 24% had a poor (modified Rankin scale 4-6) functional outcome at discharge. Higher Dbil levels were associated with greater stroke severity (P = .001) and poorer discharge outcome (P = .034). Multivariable regression analyses showed that those with higher Dbil levels (> or =0.4 mg/dL) had significantly greater admission NIHSS scores compared with those with lower levels (< or =0.1 mg/dL) (odds ratio 2.79, 95% confidence interval 1.25-6.20, P = .012), but no independent relationship was confirmed between Dbil and discharge outcome. Although higher admission Tbil was associated with greater stroke severity in crude analyses (P = .003), no independent relationship between Tbil versus stroke severity or outcome was noted after adjusting for confounders.

CONCLUSIONS

Higher Dbil level is associated with greater stroke severity but not outcome among ischemic stroke patients, possibly reflecting the intensity of initial oxidative stress. Further study into the underlying pathophysiology of this relationship is needed.

Diabetes mellitus, insulin resistance, hyperglycemia, and stroke

It is well established that diabetes is associated with an increased risk of stroke. Once a stroke has occurred, patients with diabetes experience poorer outcomes (functional status, mortality). Convincing data now support aggressive glucose control and comprehensive cardiovascular risk factor management to prevent stroke in patients with diabetes. However, there remains a distinct paucity of information concerning secondary stroke prevention. Hyperglycemia in the acute stroke setting is a marker for poor outcomes, but it remains unclear whether intensive in-hospital lowering of blood glucose levels improves clinical outcomes. Targeting insulin resistance as a modifiable risk factor for stroke is a novel strategy currently under investigation.

Predictors of outcome in acute ischemic cerebrovascular syndromes: The GIFA study

BACKGROUND

Today it may be more useful to use the term acute ischemic cerebrovascular syndrome (AICS) to define a spectrum of disease ranging from TIA to stroke and that share a similar underlying pathophysiology: cerebral ischemia. The aim of this study is to evaluate the prognostic importance of some demographic, laboratory and clinical variables on the outcome in hospitalized patients with a discharge diagnosis suggestive of acute ischemic cerebral syndrome (AICS).

METHODS

17,377 Subjects were enrolled in the GIFA study, a multicenter survey of hospitalized older patients. 1878 Subjects with a main discharge diagnosis suggestive of acute ischemic cerebrovascular syndrome (AICS) represent the final sample. The primary outcomes of this study were: (1) in-hospital mortality; (2) cognitive impairment at discharge; (3) functional status at discharge.

RESULTS

Age, WBC count, glucose blood level at admission and Charlson index score were directly associated with in-hospital mortality. Age, WBC count, Charlson index score and disability at admission are directly associated with cognitive impairment at discharge. Finally, age, Charlson index score and disability at admission are directly associated with disability at discharge.

CONCLUSIONS

Our study evaluated prognosis in the light of the three main aspects of mortality, disability and cognitive impairment that showed substantial sharing for most of the prognostic factors, probably owing to the possible strict association of these outcome indicators with markers of ischemic brain damage extent (WBC) and/or individual response to an ischemic event by neuroplasticity (age, comorbidity) in subjects with AICS.

Glucose control after severe brain injury

PURPOSE OF REVIEW

A substantial body of evidence supports the use of intensive insulin therapy in general critical care practice, particularly in surgical intensive care unit patients. The impact of intensive insulin therapy on the outcome of critically ill neurological patients, however, is still controversial. While avoidance of hyperglycemia is recommended in neurointensive care, no recommendations exist regarding the optimal target for systemic glucose control after severe brain injury.

RECENT FINDINGS

An increase in brain metabolic demand leading to a deficiency in cerebral extracellular glucose has been observed in critically ill neurological patients and correlates with poor outcome. In this setting, a reduction of systemic glucose below 6 mmol/l with exogenous insulin has been found to exacerbate brain metabolic distress. Recent studies have confirmed these findings while showing intensive insulin therapy to have no substantial benefit on the outcome of critically ill neurological patients.

SUMMARY

Questions persist regarding the optimal target for glucose control after severe brain injury. Further studies are needed to analyze the impact of intensive insulin therapy on brain glucose metabolism and outcome of critically ill neurological patients. According to the available evidence, a less restrictive target for systemic glucose control (6-10 mmol/l) may be more appropriate.

Middle Cerebral Artery Infarcts Encompassing the Insula Are More Prone to Growth

Background and Purpose— Based on previous observations that infarcts encompassing the insula were linked to unfavorable clinical outcome, we hypothesized that insular damage was directly associated with worsened infarction in ischemic but potentially viable neighboring brain tissue.

Methods— Using acute diffusion- and perfusion-weighted MRI within the first 12 hours of symptom onset and a follow-up MRI on day 5 or later, we calculated the percentage of mismatch lost (PML) in 61 consecutive patients with ischemic stroke within the middle cerebral artery territory. PML denoted the percentage of mismatch tissue between diffusion-weighted imaging and mean transit time maps that eventually underwent infarction. We explored the relationship between PML and insular location using a regression model.

Results— The median PML was 17.7% (interquartile range, 3.5% to 54.2%) in insular and 2.5% (0.0% to 12.7%) in noninsular infarcts ( P <0.01). The PML correlated with the volume of abnormal regions on diffusion-weighted imaging ( P <0.01), mean transit time ( P <0.01), cerebral blood flow maps ( P <0.01), and cerebral blood volume maps ( P <0.01). A linear regression model with PML as response and with acute MRI volumes, age, and the site of vascular occlusion as covariates showed that insular involvement was an independent predictor of PML ( P =0.01). The regression model predicted an approximately 3.2-fold increase in PML with insular involvement.

Conclusions— Infarction of the insula is associated with increased conversion of ischemic but potentially viable neighboring tissues into infarction. The unfavorable tissue outcome in insular infarcts may not be a mere bystander effect from proximal middle cerebral artery occlusions.

Hyperglycaemia and mortality

Several studies over the last decade have linked hyperglycaemia on hospital admission with subsequent mortality risk. The evidence is strongest for patients with myocardial infarction or acute coronary syndromes, but evidence also links hyperglycaemia with mortality from stroke and other medical illnesses. The effect seems independent of a previous diagnosis of diabetes mellitus; indeed, some studies suggest that mortality may be higher in patients with hyperglycaemia and no previous diabetes diagnosis compared with known diabetic patients. The effect on outcome of therapeutically lowering blood glucose levels has been considered in a small number of studies, but so far the results are conflicting. Further work is needed, focusing on more standardized surveys--previous studies vary in their use of blood or plasma, as well as cut-off levels for hyperglycaemia--and larger intervention studies.

Treatment of hyperglycemia in ischemic stroke (THIS): a randomized pilot trial

BACKGROUND AND PURPOSE

Hyperglycemia may worsen brain injury during acute cerebral infarction. We tested the feasibility and tolerability of aggressive hyperglycemia correction with intravenous insulin compared with usual care during acute cerebral infarction.

METHODS

We conducted a randomized, multicenter, blinded pilot trial for patients with cerebral infarction within 12 hours after onset, a baseline glucose value >or=8.3 mmol/L (>or=150 mg/dL), and a National Institutes of Health Stroke Scale score of 3 to 22. Patients were randomized 2:1 to aggressive treatment with continuous intravenous insulin or subcutaneous insulin QID as needed (usual care). Target glucose levels were <7.2 mmol/L (<130 mg/dL) in the aggressive-treatment group and <11.1 mmol/L (<200 mg/dL) in the usual-care group. Glucose was monitored every 1 to 2 hours, and the protocol treatments continued for up to 72 hours. Final clinical outcomes were assessed at 3 months.

RESULTS

We randomized 46 patients (31 to aggressive treatment and 15 to usual care). All patients in the aggressive-treatment group and 11 (73%) in the usual-care group had diabetes (P=0.008). Glucose levels were significantly lower in the aggressive-treatment group throughout protocol treatment (7.4 vs 10.5 mmol/L [133 vs 190 mg/dL], P<0.001). Hypoglycemia <3.3 mmol/L (<60 mg/dL) occurred only in the aggressive-treatment group (11 patients, 35%), 4 (13%) of whom had brief symptoms, including only 1 (3%) neurologic. Final clinical outcomes were nonsignificantly better in the aggressive-treatment group.

CONCLUSIONS

The intravenous insulin protocol corrected hyperglycemia during acute cerebral infarction significantly better than usual care without major adverse events and should be investigated in a clinical efficacy trial.

EMS management of acute stroke--out-of-hospital treatment and stroke system development (resource document to NAEMSP position statement)

The American Heart Association estimates an annual incidence of stroke in the United States at 700,000, leading to over 150,000 deaths. Of all strokes, approximately 88% are ischemic and 12% are hemorrhagic. Almost half of all stroke deaths occur in the out-of-hospital environment. Within a given region, the emergency medical services (EMS) system has an important role in the management of the acute stroke patient. Decisions made by EMS personnel can affect treatment and contribute to the immediate, short-term, and long-term outcomes of the patient. Because the patient may require emergent treatment regardless if the stroke is ischemic or hemorrhagic, EMS personnel should manage all potential stroke patients in a time-dependent nature. Proper treatment and disposition of the stroke patient begins in the out-of-hospital environment, continues in the emergency department, and then extends to the inpatient admission. This article reviews the literature on the out-of-hospital treatment of stroke patients and the role of EMS in the development of stroke systems of care.

Increased hemorrhagic transformation and altered infarct size and localization after experimental stroke in a rat model type 2 diabetes

BACKGROUND

Interruption of flow through of cerebral blood vessels results in acute ischemic stroke. Subsequent breakdown of the blood brain barrier increases cerebral injury by the development of vasogenic edema and secondary hemorrhage known as hemorrhagic transformation (HT). Diabetes is a risk factor for stroke as well as poor outcome of stroke. The current study tested the hypothesis that diabetes-induced changes in the cerebral vasculature increase the risk of HT and augment ischemic injury.

METHODS

Diabetic Goto-Kakizaki (GK) or control rats underwent 3 hours of middle cerebral artery occlusion and 21 h reperfusion followed by evaluation of infarct size, hemorrhage and neurological outcome.

RESULTS

Infarct size was significantly smaller in GK rats (10 +/- 2 vs 30 +/- 4%, p < 0.001). There was significantly more frequent hematoma formation in the ischemic hemisphere in GK rats as opposed to controls. Cerebrovascular tortuosity index was increased in the GK model (1.13 +/- 0.01 vs 1.34 +/- 0.06, P < 0.001) indicative of changes in vessel architecture.

CONCLUSION

These findings provide evidence that there is cerebrovascular remodeling in diabetes. While diabetes-induced remodeling appears to prevent infarct expansion, these changes in blood vessels increase the risk for HT possibly exacerbating neurovascular damage due to cerebral ischemia/reperfusion in diabetes.

Impact of hyperglycemia on ischemic stroke mortality in diabetic and non-diabetic patients

BACKGROUND

Previous studies suggest that infarct expansion may be responsible for increased mortality after stroke onset in patients with prolonged stress hyperglycemia. Therefore, we evaluated the influence of prolonged stress hyperglycemia on stroke mortality in patients with and without diabetes.

PATIENTS AND METHODS

For 630 stroke patients admitted to the neurological intensive care department within 24 hours of stroke onset, we correlated mean blood glucose levels (MBGL) at admission and 72 hours after admission in diabetic and non-diabetic patients with final outcome. Blood glucose levels higher then 6.1 mmol/L (121 mg/dL) were treated as hyperglycemia.

RESULTS

Of 630 patients (mean age 71 A+/- 6), 410 were non-diabetic (mortality, 25%) and 220 patients were diabetic (mortality, 20%). All patients who died within 28 days of hospitalization had prolonged hyperglycemia (at admission and after 72 hours, despite insulin therapy). The unadjusted relative risk of in-hospital mortality within 28 days for all stroke patients was 0.68 (95% CI, 0.14-1.9) for non-diabetic patients and 0.39 (95% CI, 0.27- 1.56) for diabetic patients. The unadjusted relative risk of in-hospital mortality within 28 days in ischemic stroke in patients with MBGL > 6.1-8.0 mmol/L (121-144 mg/dL) at admission and after 72 hours was 1.83 (95% CI, 0.41-5.5) for non-diabetic patients and 1.13 (95% CI, 0.78-4.5) for diabetic patients. Non-diabetic patients with hyperglycemia had a 1.7 times higher relative risk of in-hospital 28-day mortality than patients with diabetes.

CONCLUSION

Prolonged stress hyperglycemia in ischemic stroke patients increases the risk of in-hospital 28- day mortality, especially in non-diabetic patients.

Effect of sustained-mild and transient-severe hyperglycemia on ischemia-induced blood-brain barrier opening

The purpose of this study was to examine what levels of hyperglycemia cause blood-brain barrier (BBB) disruption during permanent and transient middle cerebral artery occlusion in the rat and when the adverse effects of hyperglycemia occur. Cerebrovascular function was assessed by measuring the influx rate constant (K(i)) for (3)H-inulin and by measuring cerebral plasma ((14)C-inulin) and (51)Cr-labeled red blood cell (RBC) volume. Different glucose protocols were used to produce mild sustained hyperglycemia (blood glucose approximately 150 mg/dL) or transient-severe hyperglycemia (with a spike in blood glucose of approximately 400 mg/dL). As expected, transient-severe hyperglycemia at the time of occlusion induced marked BBB disruption in animals undergoing 2 h of ischemia with 2 h of reperfusion (25-fold increase in permeability compared with the contralateral core). However, the mild hyperglycemia model induced similar disruption. Similarly, after permanent occlusion, both hyperglycemia models enhanced disruption and they both produced marked ( approximately 50%) reductions in cerebral plasma volume. Apparent cerebral RBC volume also decreased when measured during the final 5 mins of 2 h of ischemia with transient-severe hyperglycemia. However, there was no decrease if the (51)Cr-labeled RBCs were circulated for the whole 2 h, indicating RBC trapping. The spike in blood glucose in the severe hyperglycemia model was used to examine when hyperglycemia induced BBB disruption. Hyperglycemia shortly after occlusion caused severe disruption. In contrast, hyperglycemia after 90 mins of occlusion caused little disruption. These results suggest that mild hyperglycemia has a profound effect on BBB function and that very early correction of hyperglycemia is necessary to prevent adverse effects.

Possible involvement of different connexin43 domains in plasma membrane permeabilization induced by ischemia-reperfusion

In vitro and in vivo studies support the involvement of connexin 43-based cell-cell channels and hemichannels in cell death propagation induced by ischemia-reperfusion. In this context, open connexin hemichannels in the plasma membrane have been proposed to act as accelerators of cell death. Progress on the mechanisms underlying the cell permeabilization induced by ischemia-reperfusion reveals the involvement of several factors leading to an augmented open probability and increased number of hemichannels on the cell surface. While open probability can be increased by a reduction in extracellular concentration of divalent cations and changes in covalent modifications of connexin 43 (oxidation and phosphorylation), increase in number of hemichannels requires an elevation of the intracellular free Ca(2+) concentration. Reversal of connexin 43 redox changes and membrane permeabilization can be induced by intracellular, but not extracellular, reducing agents, suggesting a cytoplasmic localization of the redox sensor(s). In agreement, hemichannels formed by connexin 45, which lacks cytoplasmic cysteines, or by connexin 43 with its C-terminal domain truncated to remove its cysteines are insensitive to reducing agents. Although further studies are required for a precise localization of the redox sensor of connexin 43 hemichannels, modulation of the redox potential is proposed as a target for the design of pharmacological tools to reduce cell death induced by ischemia-reperfusion in connexin 43-expressing cells.

The role of hyperglycemia in acute ischemic stroke

Stroke remains a leading cause of death and long-term disability in the developed world. Reperfusion and anti-thrombotic therapies are of limited benefit for the majority of patients following acute ischemic stroke, and increasing interest has focused on therapeutic approaches that seek to modulate infarct evolution. Animal and human studies have linked hyperglycemia in the acute phase of ischemic stroke to worse clinical outcomes regardless of the presence of pre-existing diabetes mellitus. Experimental data suggest that elevated blood glucose may directly contribute to infarct expansion through a number of maladaptive metabolic pathways, and that treatment with insulin may attenuate these adverse effects. In this review, we analyze the relationship between elevated serum glucose and acute cerebrovascular ischemia, and critically appraise the potential of a clinical strategy that targets euglycemia in all acute stroke patients.

Guidelines for the Early Management of Adults With Ischemic Stroke

Purpose— Our goal is to provide an overview of the current evidence about components of the evaluation and treatment of adults with acute ischemic stroke. The intended audience is physicians and other emergency healthcare providers who treat patients within the first 48 hours after stroke. In addition, information for healthcare policy makers is included.

Methods— Members of the panel were appointed by the American Heart Association Stroke Council’s Scientific Statement Oversight Committee and represented different areas of expertise. The panel reviewed the relevant literature with an emphasis on reports published since 2003 and used the American Heart Association Stroke Council’s Levels of Evidence grading algorithm to rate the evidence and to make recommendations. After approval of the statement by the panel, it underwent peer review and approval by the American Heart Association Science Advisory and Coordinating Committee. It is intended that this guideline be fully updated in 3 years.

Results— Management of patients with acute ischemic stroke remains multifaceted and includes several aspects of care that have not been tested in clinical trials. This statement includes recommendations for management from the first contact by emergency medical services personnel through initial admission to the hospital. Intravenous administration of recombinant tissue plasminogen activator remains the most beneficial proven intervention for emergency treatment of stroke. Several interventions, including intra-arterial administration of thrombolytic agents and mechanical interventions, show promise. Because many of the recommendations are based on limited data, additional research on treatment of acute ischemic stroke is needed.

Guidelines for the early management of adults with ischemic stroke: a guideline from the American Heart Association/American Stroke Association Stroke Council, Clinical Cardiology Council, Cardiovascular Radiology and Intervention Council, and the Atherosclerotic Peripheral Vascular Disease and Quality of Care Outcomes in Research Interdisciplinary Working Groups: the American Academy of Neurology affirms the value of this guideline as an educational tool for neurologists

PURPOSE

Our goal is to provide an overview of the current evidence about components of the evaluation and treatment of adults with acute ischemic stroke. The intended audience is physicians and other emergency healthcare providers who treat patients within the first 48 hours after stroke. In addition, information for healthcare policy makers is included.

METHODS

Members of the panel were appointed by the American Heart Association Stroke Council's Scientific Statement Oversight Committee and represented different areas of expertise. The panel reviewed the relevant literature with an emphasis on reports published since 2003 and used the American Heart Association Stroke Council's Levels of Evidence grading algorithm to rate the evidence and to make recommendations. After approval of the statement by the panel, it underwent peer review and approval by the American Heart Association Science Advisory and Coordinating Committee. It is intended that this guideline be fully updated in 3 years.

RESULTS

Management of patients with acute ischemic stroke remains multifaceted and includes several aspects of care that have not been tested in clinical trials. This statement includes recommendations for management from the first contact by emergency medical services personnel through initial admission to the hospital. Intravenous administration of recombinant tissue plasminogen activator remains the most beneficial proven intervention for emergency treatment of stroke. Several interventions, including intra-arterial administration of thrombolytic agents and mechanical interventions, show promise. Because many of the recommendations are based on limited data, additional research on treatment of acute ischemic stroke is needed.

Critical care of acute ischemic stroke

Stroke is the third leading cause of death and the leading cause of disability in the United States. This article summarizes the critical care of acute ischemic stroke, including conventional and novel therapies. The article provided an overview of the initial management, diagnostic workup, treatment options, and supportive measures that need to be considered in the acute phase of ischemic stroke.

Comparative study on the effect of enteral feeding on blood glucose

Stress hyperglycaemia is common in intensive care patients. There is recent evidence to suggest that maintaining the blood glucose of a patient in intensive care between 4 mmol/litre and 6.1 mmol/litre reduces morbidity and mortality. The aim of this comparative study was to determine if blood glucose control improves with abolishing feeding breaks and introducing continuous enteral feeding. Twenty ventilated patients admitted to a combined medical and surgical intensive care unit were sampled. Ten patients received standard care (enteral feeding for 18 hours with an 8-hour break). The interventional group received continuous enteral feeding over the 24 hours. Analysis of the data revealed that continuous enteral feeding reduced blood glucose levels significantly, improved blood glucose control and reduced insulin requirements. Research should continue to determine if the results of this study could be replicated within a larger group of intensive care patients.