Prediction of malignant course in MCA infarction by PET and microdialysis

Association between Peripheral Arterial Lactate Levels and Malignant Brain Edema Following Endovascular Treatment for Ischemic Stroke

AIMS

To investigate the factors of postoperative malignant brain edema (MBE) in patients with acute ischemic stroke (AIS) treated with endovascular treatment (EVT).

BACKGROUND

MBE is a severe complication following EVT for AIS, and it is essential to identify risk factors early. Peripheral arterial lactate (PAL) levels may serve as a potential predictive marker for MBE.

OBJECTIVE

To determine whether immediate postoperative PAL levels and the highest PAL level within 24 hours of EVT are independently associated with MBE development in AIS patients.

METHODS

We retrospectively analyzed patients with AIS who underwent EVT from October 2019 to October 2022. Arterial blood was collected every 8 h after EVT to measure PAL, and record the immediate postoperative PAL and the highest PAL level within 24 h. Brain edema was evaluated using brain computed tomography scans within 7 days of EVT.

RESULTS

The study included 227 patients with a median age of 71 years, of whom 59.5% were male and MBE developed in 25.6% of patients (58/227). Multivariate logistic regression analysis showed that the immediate postoperative PAL (odds ratio, 1.809 [95% confidence interval (CI), 1.215-2.693]; p = 0.004) and the highest PAL level within 24 h of EVT (odds ratio, 2.259 [95% CI, 1.407-3.629]; p = 0.001) were independently associated with MBE. The area under the curve for predicting MBE based on the highest PAL level within 24 hours of EVT was 0.780 (95% CI, 0.711-0.849).

CONCLUSION

Early increase in PAL levels is an independent predictor of MBE after EVT in AIS patients.

Blood and Brain Metabolites after Cerebral Ischemia

The study of an organism's response to cerebral ischemia at different levels is essential to understanding the mechanism of the injury and protection. A great interest is devoted to finding the links between quantitative metabolic changes and post-ischemic damage. This work aims to summarize the outcomes of the most studied metabolites in brain tissue-lactate, glutamine, GABA (4-aminobutyric acid), glutamate, and NAA (N-acetyl aspartate)-regarding their biological function in physiological conditions and their role after cerebral ischemia/reperfusion. We focused on ischemic damage and post-ischemic recovery in both experimental-including our results-as well as clinical studies. We discuss the role of blood glucose in view of the diverse impact of hyperglycemia, whether experimentally induced, caused by insulin resistance, or developed as a stress response to the cerebral ischemic event. Additionally, based on our and other studies, we analyze and critically discuss post-ischemic alterations in energy metabolites and the elevation of blood ketone bodies observed in the studies on rodents. To complete the schema, we discuss alterations in blood plasma circulating amino acids after cerebral ischemia. So far, no fundamental brain or blood metabolite(s) has been recognized as a relevant biological marker with the feasibility to determine the post-ischemic outcome or extent of ischemic damage. However, studies from our group on rats subjected to protective ischemic preconditioning showed that these animals did not develop post-ischemic hyperglycemia and manifested a decreased metabolic infringement and faster metabolomic recovery. The metabolomic approach is an additional tool for understanding damaging and/or restorative processes within the affected brain region reflected in the blood to uncover the response of the whole organism via interorgan metabolic communications to the stressful cerebral ischemic challenge.

Surgery for Malignant Acute Ischemic Stroke: A Narrative Review of the Knowns and Unknowns

Malignant acute ischemic stroke (AIS) is characterized by acute neurological deterioration caused by progressive space-occupying brain edema, often occurring in the first hours to days after symptom onset. Without any treatment, the result is often fatal. Despite advances in treatment for AIS, up to 80% of patients with a large hemispheric stroke or cerebellar stroke are at risk of poor outcome. Decompressive surgery can be life-saving in a subgroup of patients with malignant AIS, but uncertainties exist on patient selection, predictors of malignant infarction, perioperative management, and timing of intervention. Although survivors are left disabled, most agree with the original decision to undergo surgery and would make the same decision again. In this narrative review, we focus on the clinical and radiological predictors of malignant infarction in AIS and outline the technical aspects of decompressive surgery as well as duraplasty and cranioplasty. We discuss the current evidence and recommendations for surgery in AIS, highlighting gaps in knowledge, and suggest directions for future studies. KEY POINTS: · Acute ischemic stroke from occlusion of a proximal intracranial artery can progress quickly to malignant edema, which can be fatal in 80% of patients despite medical management.. · Decompression surgery is life-saving within 48 hours of stroke onset, but the benefits beyond this time and in the elderly are unknown.. · Decompressive surgery is associated with high morbidity, particularly in the elderly. The decision to operate must be made after considering the individual's preference and expectations of quality of life in the context of the clinical condition.. · Further studies are needed to refine surgical technique including value of duraplasty and understand the role monitoring intracranial pressure during and after decompressive surgery.. · More studies are needed on the pathophysiology of malignant cerebral edema, prediction models including imaging and biomarkers to identify which subgroup of patients will benefit from decompressive surgery.. · More research is needed on factors associated with morbidity and mortality after cranioplasty, safety and efficacy of implants, and comparisons between them.. · Further studies are needed to assess the long-term effects of physical disability and quality of life of survivors after surgery, particularly those with severe neurological deficits..

Comparison of image quality between a novel mobile CT scanner and current generation stationary CT scanners

PURPOSE

Point-of-care imaging with mobile CT scanners offers several advantages, provided that the image quality is satisfactory. Our aim was to compare image quality of a novel mobile CT to stationary scanners for patients in a neurosurgical intensive care unit (ICU).

METHODS

From November 2020 to April 2021, all patients above 18 years of age examined by a mobile CT scanner at a neurosurgical ICU were included if they also had a stationary head CT examination during the same hospitalization. Quantitative image quality parameters included attenuation and noise in six predefined regions of interest, as well as contrast-to-noise ratio between gray and white matter. Subjective image quality was rated on a 4-garde scale, by four radiologists blinded to scanner parameters.

RESULTS

Fifty patients were included in the final study population. Radiation dose and image attenuation values were similar for mobCT and stationary CTs. There was a small statistically significant difference in subjective quality rating between mobCT and stationary CT images. Two radiologists favored the stationary CT images, one was neutral, and one favored mobCT images. For overall image quality, 14% of mobCT images were rated grade 1 (poor image quality) compared to 8% for stationary CT images.

CONCLUSION

Point-of-care brain CT imaging was successfully performed on clinical neurosurgical ICU patients with small reduction in image quality, predominantly affecting the posterior fossa, compared to high-end stationary CT scanners.

Bedside detection of intracranial midline shift using portable magnetic resonance imaging

Neuroimaging is crucial for assessing mass effect in brain-injured patients. Transport to an imaging suite, however, is challenging for critically ill patients. We evaluated the use of a low magnetic field, portable MRI (pMRI) for assessing midline shift (MLS). In this observational study, 0.064 T pMRI exams were performed on stroke patients admitted to the neuroscience intensive care unit at Yale New Haven Hospital. Dichotomous (present or absent) and continuous MLS measurements were obtained on pMRI exams and locally available and accessible standard-of-care imaging exams (CT or MRI). We evaluated the agreement between pMRI and standard-of-care measurements. Additionally, we assessed the relationship between pMRI-based MLS and functional outcome (modified Rankin Scale). A total of 102 patients were included in the final study (48 ischemic stroke; 54 intracranial hemorrhage). There was significant concordance between pMRI and standard-of-care measurements (dichotomous, κ = 0.87; continuous, ICC = 0.94). Low-field pMRI identified MLS with a sensitivity of 0.93 and specificity of 0.96. Moreover, pMRI MLS assessments predicted poor clinical outcome at discharge (dichotomous: adjusted OR 7.98, 95% CI 2.07–40.04, p = 0.005; continuous: adjusted OR 1.59, 95% CI 1.11–2.49, p = 0.021). Low-field pMRI may serve as a valuable bedside tool for detecting mass effect.

Multimodal Monitoring in Large Hemispheric Infarction: Quantitative Electroencephalography Combined With Transcranial Doppler for Prognosis Prediction

Background: We aimed to explore whether transcranial Doppler (TCD) combined with quantitative electroencephalography (QEEG) can improve prognosis evaluation in patients with a large hemispheric infarction (LHI) and to establish an accurate prognosis prediction model.

Methods: We prospectively assessed 90-day mortality in patients with LHI. Brain function was monitored using TCD-QEEG at the bedside of the patient.

Results: Of the 59 (55.3 ± 10.6 years; 17 men) enrolled patients, 37 (67.3%) patients died within 90 days. The Cox regression analyses revealed that the Glasgow Coma Scale (GCS) score ≤ 8 [hazard ratio (HR), 3.228; 95% CI, 1.335–7.801; p = 0.009], TCD-terminal internal carotid artery as the offending vessel (HR, 3.830; 95% CI, 1.301–11.271; p = 0.015), and QEEG-a (delta + theta)/(alpha + beta) ratio ≥ 3 (HR, 3.647; 95% CI, 1.170–11.373; p = 0.026) independently predicted survival duration. Combining these three factors yielded an area under the receiver operating characteristic curve of 0.905 and had better predictive accuracy than those of individual variables (p < 0.05).

Conclusion: TCD and QEEG complement the GCS score to create a reliable multimodal method for monitoring prognosis in patients with LHI.

Variability assessment of manual segmentations of ischemic lesion volume on 24-h non-contrast CT

PURPOSE

Infarct lesion volume (ILV) may serve as an imaging biomarker for clinical outcomes in the early post-treatment stage in patients with acute ischemic stroke. The aim of this study was to evaluate the inter- and intra-rater reliability of manual segmentation of ILV on follow-up non-contrast CT (NCCT) scans.

METHODS

Fifty patients from the Prove-IT study were randomly selected for this analysis. Three raters manually segmented ILV on 24-h NCCT scans, slice by slice, three times. The reference standard for ILV was generated by the Simultaneous Truth And Performance Level estimation (STAPLE) algorithm. Intra- and inter-rater reliability was evaluated, using metrics of intraclass correlation coefficient (ICC) regarding lesion volume and the Dice similarity coefficient (DSC).

RESULTS

Median age of the 50 subjects included was 74.5 years (interquartile range [IQR] 67-80), 54% were women, median baseline National Institutes of Health Stroke Scale was 18 (IQR 11-22), median baseline ASPECTS was 9 (IQR 6-10). The mean reference standard ILV was 92.5 ml (standard deviation (SD) ± 100.9 ml). The manually segmented ILV ranged from 88.2 ± 91.5 to 135.5 ± 119.9 ml (means referring to the variation between readers, SD within readers). Inter-rater ICC was 0.83 (95%CI: 0.76-0.88); intra-rater ICC ranged from 0.85 (95%CI: 0.72-0.92) to 0.95 (95%CI: 0.91-0.97). The mean DSC among the three readers ranged from 65.5 ± 22.9 to 76.4 ± 17.1% and the mean overall DSC was 72.8 ± 23.0%.

CONCLUSION

Manual ILV measurements on follow-up CT scans are reliable to measure the radiological outcome despite some variability.

20-hydroxyeiscosatetraenoic acid may be as a predictor of malignant middle cerebral artery infarction in patients with massive middle cerebral artery infarction

Background

Early identification of massive middle cerebral artery infarction (MCAI) at risk for malignant MCAI (m-MCAI) may be useful in selecting patients for aggressive therapies. The aim of this study was to determine whether CYP metabolites may help to predict impending m-MCAI.

Methods

This is a prospective, two-center observational study in 256 patients with acute massive MCAI. Plasma levels of 20-hydroxyeicosatetraenoic acid (20-HETE), epoxyeicosatrienoic acids, and dihydroxyeicosatrienoic acids were measured at admission. Brain computed tomography (CT) was performed at admission and repeated between day 3 and 7, or earlier if there was neurological deterioration. The primary outcome was m-MCAI. The m-MCAI was diagnosed when follow-up brain CT detected a more than two-thirds space-occupying MCAI with midline shift, compression of the basal cisterns, and neurological worsening.

Results

In total of 256 enrolled patients, 77 (30.1%) patients developed m-MCAI. Among the 77 patients with m-MCAI, 60 (77.9%) patients died during 3 months of stroke onset. 20-HETE level on admission was significantly higher in patients with m-MCAI than those without m-MCAI. There was an increase in the risk of m-MCAI with increase of 20-HETE levels. The third and fourth quartiles of 20-HETE levels were independent predictors of m-MCAI (OR: 2.86; 95% CI: 1.16 – 6.68; P = 0.025, and OR: 4.23; 95% CI: 1.35 – 8.26; P = 0.002, respectively).

Conclusions

Incidence of m-MCAI was high in patients with massive MCAI and the prognosis of m-MCAI is very poor. Elevated plasma 20-HETE may be as a predictor for m-MCAI in acute massive MCAI, and it might useful in clinical practice in therapeutic decision making.

Accelerating Prediction of Malignant Cerebral Edema After Ischemic Stroke with Automated Image Analysis and Explainable Neural Networks

BACKGROUND

Malignant cerebral edema is a devastating complication of stroke, resulting in deterioration and death if hemicraniectomy is not performed prior to herniation. Current approaches for predicting this relatively rare complication often require advanced imaging and still suffer from suboptimal performance. We performed a pilot study to evaluate whether neural networks incorporating data extracted from routine computed tomography (CT) imaging could enhance prediction of edema in a large diverse stroke cohort.

METHODS

An automated imaging pipeline retrospectively extracted volumetric data, including cerebrospinal fluid (CSF) volumes and the hemispheric CSF volume ratio, from baseline and 24 h CT scans performed in participants of an international stroke cohort study. Fully connected and long short-term memory (LSTM) neural networks were trained using serial clinical and imaging data to predict those who would require hemicraniectomy or die with midline shift. The performance of these models was tested, in comparison with regression models and the Enhanced Detection of Edema in Malignant Anterior Circulation Stroke (EDEMA) score, using cross-validation to construct precision-recall curves.

RESULTS

Twenty of 598 patients developed malignant edema (12 required surgery, 8 died). The regression model provided 95% recall but only 32% precision (area under the precision-recall curve [AUPRC] 0.74), similar to the EDEMA score (precision 28%, AUPRC 0.66). The fully connected network did not perform better (precision 33%, AUPRC 0.71), but the LSTM model provided 100% recall and 87% precision (AUPRC 0.97) in the overall cohort and the subgroup with a National Institutes of Health Stroke Scale (NIHSS) score ≥ 8 (p = 0.0001 vs. regression and fully connected models). Features providing the most predictive importance were the hemispheric CSF ratio and NIHSS score measured at 24 h.

CONCLUSIONS

An LSTM neural network incorporating volumetric data extracted from routine CT scans identified all cases of malignant cerebral edema by 24 h after stroke, with significantly fewer false positives than a fully connected neural network, regression model, and the validated EDEMA score. This preliminary work requires prospective validation but provides proof of principle that a deep learning framework could assist in selecting patients for surgery prior to deterioration.

The association between white matter changes and development of malignant middle cerebral artery infarction: A case-control study

ABSTRACT

Disrupted blood-brain barrier (BBB) in patients with ischemic stroke plays a critical role in malignant middle cerebral artery infarction (MMI) development.Cerebral white matter changes (WMC), particularly in the deep subcortical area or in severe one, may be also underlain by disrupted BBB. It is unclear whether the presence of WMC with potential premorbid disruption of BBB makes patients susceptible to MMI. Therefore, this study aimed to clarify any putative relationship between the MMI and WMC in terms of their severity and locations.In this case-control study, patients with infarction in the middle cerebral artery territory were retrospectively reviewed. Brain magnetic resonance images were analyzed according to Fazekas scale, and identified WMC were divided into periventricular WMC (PV-WMC) and deep subcortical WMC (deep-WMC). Patients were scored as having WMC, PV-WMC, deep-WMC, severe PV-WMC, and severe deep-WMC according to the severity and locations. Patients were defined as having MMI if either a progressive conscious disturbance or signs of uncal herniation was recorded in combination with a midline shift >5 mm identified on the follow-up computed tomography.Among 297 patients admitted between July 2009 and February 2015, 92 patients were eligible for final analysis. Compared to patients without MMI, patients with MMI had a higher score of National Institutes of Health Stroke Scale, a larger infarct volume, and an increasingly greater proportion of severe PV-WMC, deep-WMC, and severe deep-WMC, respectively. After adjustment for sex, age, infarct volume, and history of hypertension, severe deep-WMC (odds ratio [OR] = 6.362, 95% confidence interval [CI] = 1.444-28.023, P = .0144) and severe PV-WMC (odds ratio = 5.608, 95% confidence interval = 1.107-28.399, P = .0372) were significantly associated with MMI development.MMI and WMC are significantly associated such that MMI development is more likely when PV-WMC or deep-WMC is more severe. We hypothesize that Fazekas scale-defined severe deep-WMC and PV-WMC may be considered as clinically approachable predictors of MMI development. These findings support that the WMC with potential premorbid disrupted BBB may make patients susceptible to MMI, and further prospective study should be conducted to clarify this hypothesis.

Net Water Uptake Calculated in Standardized and Blindly Outlined Regions of the Middle Cerebral Artery Territory Predicts the Development of Malignant Edema in Patients With Acute Large Hemispheric Infarction

Background and purpose: Previous studies have demonstrated that Net Water Uptake (NWU) is associated with the development of malignant edema (ME). The current study aimed to investigate whether NWU calculated in standardized and blindly outlined regions of the middle cerebral artery can predict the development of ME. Methods: We retrospectively included 119 patients suffering from large hemispheric infarction within onset of 24 h. The region of the middle cerebral artery territory was blindly outlined in a standard manner to calculate NWU. Patients were divided into two groups according to the occurrence of ME, which is defined as space-occupying infarct requiring decompressive craniotomy or death due to cerebral hernia in 7 days from onset. The clinical characteristics were analyzed, and the receiver operating characteristic curve (ROC curve) was used to assess the predictive ability of NWU and other factors for ME. Results: Multivariable analysis showed that NWU was an independent predictor of ME (OR 1.168, 95% CI 1.041-1.310). According to the ROC curve, NWU≥8.127% identified ME with good predictive power (AUC 0.734, sensitivity 0.656, specificity 0.862). Conclusions: NWU calculated in standardized and blindly outlined regions of the middle cerebral artery territory is also a good predictor for the development of ME in patients with large hemispheric infarction.

External Validation and Modification of the EDEMA Score for Predicting Malignant Brain Edema After Acute Ischemic Stroke

BACKGROUND

Accurate prediction of malignant brain edema (MBE) after stroke is paramount to facilitate close monitoring and timely surgical intervention. The Enhanced Detection of Edema in Malignant Anterior Circulation Stroke (EDEMA) score was useful to predict potentially lethal malignant edema in Western populations. We aimed to validate and modify it to achieve a better predictive value for MBE in Chinese patients.

METHODS

Of ischemic stroke patients consecutively admitted in the Department of Neurology, West China Hospital between January 2010 and December 2017, we included patients with anterior circulation stroke, early signs of brain edema on computed tomography within 24 h of onset, and admission National Institutes of Health Stroke Scale (NIHSS) score ≥ 8. MBE was defined as the development of signs of herniation (including decrease in consciousness and/or anisocoria), accompanied by midline shift ≥ 5 mm on follow-up imaging. The EDEMA score consisted of five parameters: glucose, stroke history, reperfusion therapy, midline shift, and cistern effacement. We created a modified score by adding admission NIHSS score to the original EDEMA score. The discrimination of the score was assessed by the area under the receiver operating characteristics curve (AUC). Calibration was assessed by Hosmer-Lemeshow test and calibration plot. We compared the discrimination of the original and modified score by AUC, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Clinical usefulness of the two scores was compared by plotting net benefits at different threshold probabilities in the decision curve analysis.

RESULTS

Of the 478 eligible patients (mean age 67.3 years; median NIHSS score 16), 93 (19%) developed MBE. The EDEMA score showed moderate discrimination (AUC 0.72, 95% confidence interval [CI] 0.67-0.76) and good calibration (Hosmer-Lemeshow test, P = 0.77). The modified score showed an improved discriminative ability (AUC 0.80, 95% CI 0.76-0.84, P < 0.001; NRI 0.67, 95% CI 0.55-0.78, P < 0.001; IDI 0.07, 95% CI 0.06-0.09, P < 0.001). Decision curves showed that the modified score had a higher net benefit than the original score in a range of threshold probabilities lower than 60%.

CONCLUSIONS

The original EDEMA score showed an acceptable predictive value for MBE in Chinese patients. By adding the admission NIHSS score, the modified score allowed for a more accurate prediction and clinical usefulness. Further validation in large cohorts of different ethnicities is needed to confirm our findings.

Early neutrophil count relates to infarct size and fatal outcome after large hemispheric infarction

AIMS

To investigate the relationship between peripheral leukocyte dynamics and the outcome of large hemispheric infarction (LHI) patients.

METHODS

Patients with acute LHI admitted to the neuro-intensive care unit of Xuanwu Hospital from 2013 to 2017 were prospectively enrolled and followed up for 6 months after LHI.

RESULTS

A total of 84 LHI patients were included, 38 patients suffered brain herniation and 20 patients died from stroke. Compared to patients with benign course, LHI patients with fatal outcome showed larger infarcts and more severe brain edema (P < .01), as well as increased WBC and neutrophil counts throughout the first week after stroke (P < .05). Correlation analysis revealed that neutrophil counts on D2 after LHI positively correlated with infarct and edema volumes measured from CT/MRI (R²  = 0.22 and R²  = 0.15, P < .01) and negatively correlated with Glasgow Coma Scale (ρ = -0.234, P < .05). Patients with D2 neutrophils > 7.14 × 10⁹ /L had higher risk of brain herniation [odds ratio (OR) = 7.5, 95% CI: 2.0-28.1, P = .001], and patients with D2 neutrophils > 7.79 × 10⁹ /L had a higher risk of death (OR = 5.8, 95% CI: 1.2-27.0, P = .015).

CONCLUSION

Early peripheral neutrophil count after stroke relates to infarct size and the fatal outcome of LHI patients, which might help guiding acute LHI management such as reduction of intracranial pressure and potential antiinflammatory therapy in the future.

Early Prediction of Malignant Brain Edema After Ischemic Stroke

Background and Purpose- Malignant brain edema after ischemic stroke has high mortality but limited treatment. Therefore, early prediction is important, and we systematically reviewed predictors and predictive models to identify reliable markers for the development of malignant edema. Methods- We searched Medline and Embase from inception to March 2018 and included studies assessing predictors or predictive models for malignant brain edema after ischemic stroke. Study quality was assessed by a 17-item tool. Odds ratios, mean differences, or standardized mean differences were pooled in random-effects modeling. Predictive models were descriptively analyzed. Results- We included 38 studies (3278 patients) with 24 clinical factors, 7 domains of imaging markers, 13 serum biomarkers, and 4 models. Generally, the included studies were small and showed potential publication bias. Malignant edema was associated with younger age (n=2075; mean difference, -4.42; 95% CI, -6.63 to -2.22), higher admission National Institutes of Health Stroke Scale scores (n=807, median 17-20 versus 5.5-15), and parenchymal hypoattenuation >50% of the middle cerebral artery territory on initial computed tomography (n=420; odds ratio, 5.33; 95% CI, 2.93-9.68). Revascularization (n=1600, odds ratio, 0.37; 95% CI, 0.24-0.57) were associated with a lower risk for malignant edema. Four predictive models all showed an overall C statistic >0.70, with a risk of overfitting. Conclusions- Younger age, higher National Institutes of Health Stroke Scale, and larger parenchymal hypoattenuation on computed tomography are reliable early predictors for malignant edema. Revascularization reduces the risk of malignant edema. Future studies with robust design are needed to explore optimal cutoff age and National Institutes of Health Stroke Scale scores and to validate and improve existing models.

Effects of hyperoxia on 18F-fluoro-misonidazole brain uptake and tissue oxygen tension following middle cerebral artery occlusion in rodents: Pilot studies

PURPOSE

Mapping brain hypoxia is a major goal for stroke diagnosis, pathophysiology and treatment monitoring. 18F-fluoro-misonidazole (FMISO) positron emission tomography (PET) is the gold standard hypoxia imaging method. Normobaric hyperoxia (NBO) is a promising therapy in acute stroke. In this pilot study, we tested the straightforward hypothesis that NBO would markedly reduce FMISO uptake in ischemic brain in Wistar and spontaneously hypertensive rats (SHRs), two rat strains with distinct vulnerability to brain ischemia, mimicking clinical heterogeneity.

METHODS

Thirteen adult male rats were randomized to distal middle cerebral artery occlusion under either 30% O2 or 100% O2. FMISO was administered intravenously and PET data acquired dynamically for 3hrs, after which magnetic resonance imaging (MRI) and tetrazolium chloride (TTC) staining were carried out to map the ischemic lesion. Both FMISO tissue uptake at 2-3hrs and FMISO kinetic rate constants, determined based on previously published kinetic modelling, were obtained for the hypoxic area. In a separate group (n = 9), tissue oxygen partial pressure (PtO2) was measured in the ischemic tissue during both control and NBO conditions.

RESULTS

As expected, the FMISO PET, MRI and TTC lesion volumes were much larger in SHRs than Wistar rats in both the control and NBO conditions. NBO did not appear to substantially reduce FMISO lesion size, nor affect the FMISO kinetic rate constants in either strain. Likewise, MRI and TTC lesion volumes were unaffected. The parallel study showed the expected increases in ischemic cortex PtO2 under NBO, although these were small in some SHRs with very low baseline PtO2.

CONCLUSIONS

Despite small samples, the apparent lack of marked effects of NBO on FMISO uptake suggests that in permanent ischemia the cellular mechanisms underlying FMISO trapping in hypoxic cells may be disjointed from PtO2. Better understanding of FMISO trapping processes will be important for future applications of FMISO imaging.

Neuronal Culture Microenvironments Determine Preferences in Bioenergetic Pathway Use

In the brain, metabolic supply and demand is directly coupled to neuronal activation. Methods for culturing primary rodent brain cells have come of age and are geared toward sophisticated modeling of human brain physiology and pathology. However, the impact of the culture microenvironment on neuronal function is rarely considered. Therefore, we investigated the role of different neuronal culture supplements for neuronal survival and metabolic activity in a model of metabolic deprivation of neurons using oxygen deprivation, glucose deprivation, as well as live cell metabolic flux analysis. We demonstrate the impact of neuronal culture conditions on metabolic function and neuronal survival under conditions of metabolic stress. In particular, we find that the common neuronal cell culture supplement B27 protects neurons from cell death under hypoxic conditions and inhibits glycolysis. Furthermore, we present data that B27 as well as the alternative neuronal culture supplement N2 restrict neuronal glucose metabolism. On the contrary, we find that the more modern supplement GS21 promotes neuronal energy metabolism. Our data support the notion that careful control of the metabolic environment is an essential component in modeling brain function and the cellular and molecular pathophysiology of brain disease in culture.

Permeability surface area product analysis in malignant brain edema prediction - A pilot study

BACKGROUND AND PURPOSE

Using an extended CT perfusion acquisition (150s), we sought to determine the association between perfusion parameters and malignant edema after ischemic stroke.

METHODS

Patients (from prospective study PROVE-IT, NCT02184936) with terminal internal carotid artery±proximal middle cerebral occlusion were involved. CTA was assessed for clot location and status of leptomeningeal collaterals. The following CTP parameters were calculated within the ischemic territory and contralaterally: permeability surface area product (PS), cerebral blood flow (CBF) and cerebral blood volume (CBV). PS was calculated using the adiabatic approximation to the Johnson and Wilson model. Outcome was evaluated by midline shift and infarction volume on follow-up imaging.

RESULTS

Of 200 patients enrolled, 7 patients (3.5%) had midline shift≥5mm (2 excluded for poor-quality scans). Five patients with midline shift and 5 matched controls were analysed. There was no significant difference in mean PS, CBF and CBV within the ischemic territory between the two groups. A CBV threshold of 1.7ml/100g had the highest AUC=0.72, 95% CI=0.54-0.90 for early midline shift prediction, sensitivity and specificity were 0.83 and 0.67 respectively.

CONCLUSION

Our preliminary results did not show significant differences in permeability surface area analysis if analysed for complete ischemic region. CBV parameter had the highest accuracy and there was a trend for the mean PS values for midline shift prediction.

Consensus statement from the 2014 International Microdialysis Forum

Microdialysis enables the chemistry of the extracellular interstitial space to be monitored. Use of this technique in patients with acute brain injury has increased our understanding of the pathophysiology of several acute neurological disorders. In 2004, a consensus document on the clinical application of cerebral microdialysis was published. Since then, there have been significant advances in the clinical use of microdialysis in neurocritical care. The objective of this review is to report on the International Microdialysis Forum held in Cambridge, UK, in April 2014 and to produce a revised and updated consensus statement about its clinical use including technique, data interpretation, relationship with outcome, role in guiding therapy in neurocritical care and research applications.

CSF Volumetric Analysis for Quantification of Cerebral Edema After Hemispheric Infarction

BACKGROUND

Malignant cerebral edema (CED) complicates at least 20 % of large hemispheric infarcts (LHI) and may result in neurological deterioration or death. Midline shift (MLS) is a standard but crude measure of edema severity. We propose that volumetric analysis of shifts in cerebrospinal fluid (CSF) over time provides a reliable means of quantifying the spectrum of edema severity after LHI.

METHODS

We identified 38 patients from 2008 to 2014 with NIHSS ≥8, baseline CT <6 h after stroke onset, at least 1 follow-up (FU) CT, and no parenchymal hematoma. The volumes of CSF (sulci, ventricles, and cisterns) ipsilateral (IL) and contralateral (CL) to infarct on baseline and FU CTs were quantified by manually assisted outlining with MIPAV image analysis software, as was infarct volume and MLS on FU CTs. Percentage change in CSF volumes (∆CSF) from baseline to FU scans was correlated with MLS and compared in those with vs. without malignant edema (defined as hemicraniectomy, osmotic therapy, or death/neurological deterioration with MLS ≥5 mm).

RESULTS

11 of 38 subjects (29 %) developed malignant edema. Neither baseline NIHSS nor CSF volume differed between those with and without edema (median NIHSS 18 vs. 13, p = 0.12, CSF volume 102 vs. 124 ml, p = 0.16). Inter-rater reliability for CSF measurements was excellent (intraclass correlation coefficient 0.97). ∆CSF correlated strongly with MLS at peak edema (r = -0.75), even adjusting for infarct volume (p = 0.009). ∆CSF was also greater in those with malignant edema [-55 % (IQR -49 to -62) vs. -36 % (-27 to -45), p = 0.004]. ∆CSF was the greatest within IL sulci [-97 % (-86 to -99) vs. -71 % (-41 to -79), p = 0.002] but also significantly greater within CL sulci in those with malignant edema [-50 % (-29 to -65) vs. -25 % (0 to -31), p = 0.014]. More than half this CSF volume reduction occurred by the time of first FU CT around 24 h after stroke, while MLS rose later.

CONCLUSIONS

Volumetric CSF analysis reliably quantifies CED and distinguishes those with malignant edema and MLS from those with a more benign course after LHI. ∆CSF may provide an earlier and more sensitive indicator of edema severity across a broader dynamic range than MLS.

Hydroxysafflor Yellow A Protects Neurons From Excitotoxic Death through Inhibition of NMDARs

Excessive glutamate release causes overactivation of N-methyl d-aspartate receptors (NMDARs), leading to excitatory neuronal damage in cerebral ischemia. Hydroxysafflor yellow A (HSYA), a compound extracted from Carthamus tinctorius L., has been reported to exert a neuroprotective effect in many pathological conditions, including brain ischemia. However, the underlying mechanism of HSYA's effect on neurons remains elusive. In the present study, we conducted experiments using patch-clamp recording of mouse hippocampal slices. In addition, we performed Ca²⁺ imaging, Western blots, as well as mitochondrial-targeted circularly permuted yellow fluorescent protein transfection into cultured hippocampal neurons in order to decipher the physiological mechanism underlying HSYA's neuroprotective effect.

Through the electrophysiology experiments, we found that HSYA inhibited NMDAR-mediated excitatory postsynaptic currents without affecting α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor and γ-aminobutyric acid A-type receptor-mediated currents. This inhibitory effect of HSYA on NMDARs was concentration dependent. HSYA did not show any preferential inhibition of either N-methyl d-aspartate receptor subtype 2A- or N-methyl d-aspartate receptor subtype 2B- subunit-containing NMDARs. Additionally, HSYA exhibits a facilitatory effect on paired NMDAR-mediated excitatory postsynaptic currents. Furthermore, HSYA reduced the magnitude of NMDAR-mediated membrane depolarization currents evoked by oxygen-glucose deprivation, and suppressed oxygen-glucose deprivation–induced and NMDAR-dependent ischemic long-term potentiation, which is believed to cause severe reperfusion damage after ischemia. Through the molecular biology experiments, we found that HSYA inhibited the NMDA-induced and NMDAR-mediated intracellular Ca²⁺ concentration increase in hippocampal cultures, reduced apoptotic and necrotic cell deaths, and prevented mitochondrial damage. Together, our data demonstrate for the first time that HSYA protects hippocampal neurons from excitotoxic damage through the inhibition of NMDARs. This novel finding indicates that HSYA may be a promising pharmacological candidate for the treatment of brain ischemia.

Predicting Mortality in Patients With "Malignant" Middle Cerebral Artery Infarction Using Susceptibility-Weighted Magnetic Resonance Imaging: Preliminary Findings

To evaluate malignant middle cerebral artery (MCA) infarction (defined as space-occupying edema in more than 50% to 75% of the MCA territory) on magnetic resonance imaging (MRI) with susceptibility-weighted imaging (SWI) sequence and assess the usefulness of SWI findings, diffusion-weighted imaging (DWI) findings, and apparent diffusion coefficient (ADC) as predictors of clinical outcome.Data from 16 patients with large MCA infarction previously admitted to our institution between December 2009 and October 2012 were retrospectively collected and analyzed. Within 7 days after stroke onset, 1 neurologist and 1 neuroradiologist estimated the area of infarction on DWI/ADC and extent of prominent vessel sign (PVS) on SWI images using the Stroke Program Early MR Score (SPEMRS). The PVS on SWI was defined as a local prominence of hypointense vessels with either increased vessel number or diameter in the target area, when compared with the number or diameter of the contralateral MCA territory vessels.Six patients died and 10 survived. Although the DWI/ADC-SPEMRS and clinical profiles were similar between the nonsurvivor and survivor groups, SWI-SPEMRS was significantly lower in the nonsurvivor group (P < 0.001).The area of deoxygenation on SWI in patients with malignant MCA infarction can predict mortality. Lower SWI-SPEMRS is a potentially better predictor of poor outcome than lower DWI-SPEMRS. A larger prospective study is needed to clarify the role of SWI as a therapeutic guide in malignant MCA.

Evidence-based guidelines for the management of large hemispheric infarction : a statement for health care professionals from the Neurocritical Care Society and the German Society for Neuro-intensive Care and Emergency Medicine

Large hemispheric infarction (LHI), also known as malignant middle cerebral infarction, is a devastating disease associated with significant disability and mortality. Clinicians and family members are often faced with a paucity of high quality clinical data as they attempt to determine the most appropriate course of treatment for patients with LHI, and current stroke guidelines do not provide a detailed approach regarding the day-to-day management of these complicated patients. To address this need, the Neurocritical Care Society organized an international multidisciplinary consensus conference on the critical care management of LHI. Experts from neurocritical care, neurosurgery, neurology, interventional neuroradiology, and neuroanesthesiology from Europe and North America were recruited based on their publications and expertise. The panel devised a series of clinical questions related to LHI, and assessed the quality of data related to these questions using the Grading of Recommendation Assessment, Development and Evaluation guideline system. They then developed recommendations (denoted as strong or weak) based on the quality of the evidence, as well as the balance of benefits and harms of the studied interventions, the values and preferences of patients, and resource considerations.

Hemispheric differences in malignant middle cerebral artery stroke

BACKGROUND

We recently reported that left versus right hemisphere cerebral infarctions patients more frequently have worse outcomes. However our clinical experience led us to suspect that the incidence of malignant middle cerebral artery infarctions (MMCA) was higher in the right compared to the left hemispheric strokes.

OBJECTIVE

To determine whether laterality in MMCA stroke is an important determinant of stroke sequelae.

METHODS

A systematic search was performed for publications in PubMed using "malignant middle cerebral artery and infarction". A total of 73 relevant studies were abstracted.

RESULTS

MMCA laterality data were available for 2673 patients, with 1687 (63%) right hemispheric involvement, thus right being more commonly associated with MMCA (binomial test, p<0.05). While mortality rates were similar, right hemispheric MMCA (n=271) had mortality of 31% (n=85) whereas left hemispheric MMCA (n=144) had mortality of 36% (n=53), morbidity rates were worse on the right.

CONCLUSION

MMCA stroke appears to be more common on the right, and this laterality is also associated with significantly higher morbidity. Further prospective studies are needed to more completely understand the nature of this laterality as well as test possible new treatments to reduce mortality and morbidity associated with MMCA.

Standards of scoring, monitoring, and parameter targeting in German neurocritical care units: a national survey

BACKGROUND

Optimal management of physiological parameters in neurological/neurosurgical intensive care units (NICUs) is largely unclear as high-quality evidence is lacking. The aim of this survey was to investigate if standards exist in the use of clinical scores, systemic and cerebral monitoring and the targeting of physiology values and in what way this affects clinical management in German NICUs.

METHODS

National survey, on-line anonymized questionnaire. German departments stating to run a neurological, neurosurgical or interdisciplinary neurological/neurosurgical intensive care unit were identified by a web-based search of all German hospitals and contacted via email.

RESULTS

Responses from 78 German NICUs were obtained. Of 19 proposed clinical/laboratory/radiological scores only 5 were used regularly by >60 %. Bedside neuromonitoring (NM) predominantly consisted of transcranial Doppler sonography (94 %), electroencephalography (92 %) and measurement of intracranial pressure (ICP) (90 %), and was installed if patients had or were threatened by elevated ICP (86 %), had specific diseases like subarachnoid hemorrhage (51 %) or were comatose (35 %). Although mean trigger values for interventions complied with guidelines or wide-spread customs, individual trigger values varied widely, e.g., for hyperglycemia (maximum blood glucose between 120 and 250 mg/dl) or for anemia (minimum hemoglobin values between 5 and 10 g/dl).

CONCLUSIONS

Although apparently aiming for standardization in neurocritical care, German NICUs show substantial differences in NM and monitoring-associated interventions. In terms of scoring and monitoring methods, German NICUs seem to be quite conservative. These survey results suggest a need of prospective and randomized interventional trials in neurocritical care to help define standards and target values.

PET imaging in ischemic cerebrovascular disease: current status and future directions

Cerebrovascular diseases are caused by interruption or significant impairment of the blood supply to the brain, which leads to a cascade of metabolic and molecular alterations resulting in functional disturbance and morphological damage. These pathophysiological changes can be assessed by positron emission tomography (PET), which permits the regional measurement of physiological parameters and imaging of the distribution of molecular markers. PET has broadened our understanding of the flow and metabolic thresholds critical for the maintenance of brain function and morphology: in this application, PET has been essential in the transfer of the concept of the penumbra (tissue with perfusion below the functional threshold but above the threshold for the preservation of morphology) to clinical stroke and thereby has had great impact on developing treatment strategies. Radioligands for receptors can be used as early markers of irreversible neuronal damage and thereby can predict the size of the final infarcts; this is also important for decisions concerning invasive therapy in large ("malignant") infarctions. With PET investigations, the reserve capacity of blood supply to the brain can be tested in obstructive arteriosclerosis of the supplying arteries, and this again is essential for planning interventions. The effect of a stroke on the surrounding and contralateral primarily unaffected tissue can be investigated, and these results help to understand the symptoms caused by disturbances in functional networks. Chronic cerebrovascular disease causes vascular cognitive disorders, including vascular dementia. PET permits the detection of the metabolic disturbances responsible for cognitive impairment and dementia, and can differentiate vascular dementia from degenerative diseases. It may also help to understand the importance of neuroinflammation after stroke and its interaction with amyloid deposition in the development of dementia. Although the clinical application of PET investigations is limited, this technology had and still has a great impact on research into cerebrovascular diseases.

The role of imaging in acute ischemic stroke

Neuroimaging has expanded beyond its traditional diagnostic role and become a critical tool in the evaluation and management of stroke. The objectives of imaging include prompt accurate diagnosis, treatment triage, prognosis prediction, and secondary preventative precautions. While capitalizing on the latest treatment options and expanding upon the "time is brain" doctrine, the ultimate goal of imaging is to maximize the number of treated patients and improve the outcome of one the most costly and morbid disease. A broad overview of comprehensive multimodal stroke imaging is presented here to affirm its utilization.

Glucose and the injured brain-monitored in the neurointensive care unit

Brain has a continuous demand for energy that is met by oxidative metabolism of oxygen and glucose. This demand is compromised in the injured brain and if the inadequate supply persists it will lead to permanent tissue damage. Zero values of cerebral glucose have been associated with infarction and poor neurological outcome. Furthermore, hyperglycemia is common in patients with neurological insults and associated with poor outcome. Intensive insulin therapy (IIT) to control blood glucose has been suggested and used in neurointensive care with conflicting results. This review covers the studies reporting on monitoring of cerebral glucose with microdialysis in patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH) and ischemic stroke. Studies investigating IIT are also discussed. Available data suggest that low cerebral glucose in patients with TBI and SAH provides valuable information on development of secondary ischemia and has been correlated with worse outcome. There is also indication that the location of the catheter is important for correlation between plasma and brain glucose. In conclusion considering catheter location, monitoring of brain glucose in the neurointensive care not only provides information on imminent secondary ischemia it also reveals the effect of peripheral treatment on the injured brain.

Recommendations for the management of cerebral and cerebellar infarction with swelling: a statement for healthcare professionals from the American Heart Association/American Stroke Association

BACKGROUND AND PURPOSE

There are uncertainties surrounding the optimal management of patients with brain swelling after an ischemic stroke. Guidelines are needed on how to manage this major complication, how to provide the best comprehensive neurological and medical care, and how to best inform families facing complex decisions on surgical intervention in deteriorating patients. This scientific statement addresses the early approach to the patient with a swollen ischemic stroke in a cerebral or cerebellar hemisphere.

METHODS

The writing group used systematic literature reviews, references to published clinical and epidemiology studies, morbidity and mortality reports, clinical and public health guidelines, authoritative statements, personal files, and expert opinion to summarize existing evidence and to indicate gaps in current knowledge. The panel reviewed the most relevant articles on adults through computerized searches of the medical literature using MEDLINE, EMBASE, and Web of Science through March 2013. The evidence is organized within the context of the American Heart Association framework and is classified according to the joint American Heart Association/American College of Cardiology Foundation and supplementary American Heart Association Stroke Council methods of classifying the level of certainty and the class and level of evidence. The document underwent extensive American Heart Association internal peer review.

RESULTS

Clinical criteria are available for hemispheric (involving the entire middle cerebral artery territory or more) and cerebellar (involving the posterior inferior cerebellar artery or superior cerebellar artery) swelling caused by ischemic infarction. Clinical signs that signify deterioration in swollen supratentorial hemispheric ischemic stroke include new or further impairment of consciousness, cerebral ptosis, and changes in pupillary size. In swollen cerebellar infarction, a decrease in level of consciousness occurs as a result of brainstem compression and therefore may include early loss of corneal reflexes and the development of miosis. Standardized definitions should be established to facilitate multicenter and population-based studies of incidence, prevalence, risk factors, and outcomes. Identification of patients at high risk for brain swelling should include clinical and neuroimaging data. If a full resuscitative status is warranted in a patient with a large territorial stroke, admission to a unit with neurological monitoring capabilities is needed. These patients are best admitted to intensive care or stroke units attended by skilled and experienced physicians such as neurointensivists or vascular neurologists. Complex medical care includes airway management and mechanical ventilation, blood pressure control, fluid management, and glucose and temperature control. In swollen supratentorial hemispheric ischemic stroke, routine intracranial pressure monitoring or cerebrospinal fluid diversion is not indicated, but decompressive craniectomy with dural expansion should be considered in patients who continue to deteriorate neurologically. There is uncertainty about the efficacy of decompressive craniectomy in patients ≥60 years of age. In swollen cerebellar stroke, suboccipital craniectomy with dural expansion should be performed in patients who deteriorate neurologically. Ventriculostomy to relieve obstructive hydrocephalus after a cerebellar infarct should be accompanied by decompressive suboccipital craniectomy to avoid deterioration from upward cerebellar displacement. In swollen hemispheric supratentorial infarcts, outcome can be satisfactory, but one should anticipate that one third of patients will be severely disabled and fully dependent on care even after decompressive craniectomy. Surgery after a cerebellar infarct leads to acceptable functional outcome in most patients.

CONCLUSIONS

Swollen cerebral and cerebellar infarcts are critical conditions that warrant immediate, specialized neurointensive care and often neurosurgical intervention. Decompressive craniectomy is a necessary option in many patients. Selected patients may benefit greatly from such an approach, and although disabled, they may be functionally independent.

A proposal for the classification of etiologies of neurologic deterioration after acute ischemic stroke

BACKGROUND

Neurologic deterioration (ND) occurs in one third of patients with ischemic stroke and contributes to morbidity and mortality in these patients. Etiologies of ND and clinical outcome according to ND etiology are incompletely understood.

METHODS

We conducted a retrospective investigation of all patients with ischemic stroke admitted to our center (July 2008 to December 2010), who were known to be last seen normal less than 48 hours before arrival. First-time episodes of ND during hospitalization were collected in which a patient experienced a 2-point increase or more in National Institutes of Health Stroke Scale score within a 24-hour period. Proposed etiologies of reversible ND include infectious, metabolic, hemodynamic, focal cerebral edema, fluctuation, sedation, and seizure, whereas new stroke, progressive stroke, intracerebral hemorrhage, and cardiopulmonary arrest were nonreversible.

RESULTS

Of 366 included patients (median age 65 years, 41.4% women, 68.3% black), 128 (34.9%) experienced ND (median age 69 years, 42.2% women, 68.7% black). Probable etiologies of ND were identified in 90.6% of all first-time ND events. The most common etiology of ND, progressive stroke, was highly associated with poor outcome but not death. Etiologies most associated with mortality included edema (47.8%), new stroke (50%), and intracerebral hemorrhage (42.1%).

CONCLUSIONS

In the present study, the authors identified probable etiologies of ND after ischemic stroke. Delineating the cause of ND could play an important role in the management of the patient and help set expectations for prognosis after ND has occurred. Prospective studies are needed to validate these proposed definitions of ND.

[Multimodal monitoring in neurointensive care medicine: state of the art]

The prognosis of neurointensive care patients depends largely on the occurrence of secondary ischemic/hypoxic tissue damage, which is mediated by different pathomechanisms, such as edema formation or increased intracranial pressure. Due to the cerebral damage and need for sedation as well as intubation, clinical assessment of these patients is limited. Furthermore, clinical signs of secondary damage, such as advanced herniation syndromes are often delayed and therefore mostly indicate irreversible brain damage. To adequately predict and detect secondary neuronal damage, various neuromonitoring techniques have been developed in recent years with ongoing technical refinement. These can be used for bedside and ideally continuous monitoring of various functional systems of the brain. Neuromonitoring is used to implement early therapeutic measures before irreversible brain damage has occurred, to monitor therapeutic effects, for evaluation of the prognosis and to improve the neurological outcome of patients. Different monitoring techniques are often combined in multimodal neuromonitoring. This article gives an overview of the most promising neuromonitoring techniques available.

Malignant hemispheric infarction of the middle cerebral artery. Diagnostic considerations and treatment options

INTRODUCTION

Malignant hemispheric infarction (MHI) is a specific and devastating type of ischemic stroke. It usually affects all or part of the territory of the middle cerebral artery although its effects may extend to other territories as well. Its clinical outcome is frequently catastrophic when only conventional medical treatment is applied.

OBJECTIVE

The purpose of this review is to analyse the available scientific evidence on the treatment of this entity.

DEVELOPMENT

MHI is associated with high morbidity and mortality. Its clinical characteristics are early neurological deterioration and severe hemispheric syndrome. Its hallmark is the development of space-occupying cerebral oedema between day 1 and day 3 after symptom onset. The mass effect causes displacement, distortion, and herniation of brain structures even when intracranial hypertension is initially absent. Until recently, MHI was thought to be fatal and untreatable because mortality rates with conventional medical treatment could exceed 80%. In this unfavourable context, decompressive hemicraniectomy has re-emerged as a therapeutic alternative for selected cases, with reported decreases in mortality ranging between 15% and 40%.

CONCLUSIONS

In recent years, several randomised clinical trials have demonstrated the benefit of decompressive hemicraniectomy in patients with MHI. This treatment reduces mortality in addition to improving functional outcomes.

Recirculation usually precedes malignant edema in middle cerebral artery infarcts

OBJECTIVES

In patients with large middle cerebral artery (MCA) infarcts, maximum brain swelling leading to cerebral herniation and death usually occurs 2-5 days after onset of stroke. The study aimed at exploring the pattern of compounds related to cerebral energy metabolism in infarcted brain tissue.

METHODS

Forty-four patients with malignant MCA infarcts were included after decision to perform decompressive hemicraniectomy (DHC). Cerebral energy metabolism was in all patients monitored bedside by 1-3 microdialysis catheters inserted into the infarcted hemisphere during DHC. In 29 of the patients, one microdialysis catheter was also placed in the non-infarcted hemisphere. MCA blood-flow velocity was monitored bilaterally by transcranial Doppler ultrasound.

RESULTS

The interstitial glucose levels were in both sides within normal limits throughout the monitoring period. Mean lactate/pyruvate (LP) ratio was very high in infarcted tissue immediately after DHC. The ratio slowly decreased but did not reach normal level during the study period. In the infarcted hemisphere, MCA blood-flow velocities increased from approximately 42 cm/s 1 day prior to DHC (nine of nine patients) to approximately 60 cm/s at day 4.

CONCLUSIONS

Normal interstitial glucose level in the infarcted hemisphere in combination with substantial MCA blood-flow velocities bilaterally even before DHC was performed indicates that malignant brain swelling usually commences when the embolus/thrombosis has been largely resolved and recirculation of the infarcted area has started. The protracted increase of the LP ratio in infarcted tissue might indicate mitochondrial dysfunction.

Cerebroside-A provides potent neuroprotection after cerebral ischaemia through reducing glutamate release and Ca²⁺ influx of NMDA receptors

Excessive presynaptic glutamate release after cerebral ischaemia leads to neuronal death mainly through excessive calcium entry of N-methyl-D-aspartate receptors (NMDARs). Our recent study reported that cerebroside can open large-conductance Ca²⁺-activated K⁺ (BKCa) channels. The present study evaluated the effects of cerebroside-A (CS-A), a single molecule isolated from an edible mushroom, on brain injury after focal or global ischaemia in adult male mice and rats. We herein report that treatment with CS-A after 60-min middle cerebral artery occlusion dose-dependently reduced the cerebral infarction with at least a 6-h efficacious time-window, which was partially blocked by the BKCa channel blocker charybdotoxin (CTX). Treatment with CS-A after 20 min global cerebral ischaemia (four-vessel occlusion) significantly attenuated the death of pyramidal cells in hippocampal CA1 area, which was also sensitive to CTX. CS-A, by opening the BKCa channel, could prevent excessive glutamate release after oxygen-glucose deprivation (OGD). In addition, CS-A could inhibit NMDAR Ca²⁺ influx, which did not require the activation of the BKCa channel. Furthermore, CS-A blocked the OGD-induced NMDAR-dependent long-term potentiation in hippocampal CA1 region. These findings indicate that treatment with CS-A after stroke exerts potent neuroprotection through prevention of excessive glutamate release and reduction of Ca²⁺ influx through NMDARs.

Prognostic value of electroencephalography and evoked potentials in the early course of malignant middle cerebral artery infarction

Space-occupying brain edema may lead to a malignant course in patients with large middle cerebral artery infarction. Decompressive hemicraniectomy has to be initiated early to prevent further tissue damage. In this retrospective study, we analyzed electroencephalography (EEG) and evoked potentials (EPs), obtained within 24 h after onset of stroke, in 22 patients suffering from a large middle cerebral artery infarction. Our findings indicate a prognostic value of EEG and brainstem auditory EP (BAEP): the absence of delta activity and the presence of theta and fast beta frequencies within EEG-focus predicted a non-malignant course. In contrast, diffuse generalized slowing and slow delta activity in the ischemic hemisphere pointed to a malignant course. Likewise, pathological BAEP were correlated with a malignant course. The coexistence of background slowing and pathological BAEP showed the highest level of significance. In conclusion, our findings implicate an additional early application of electrophysiological methods in stroke patients. EEG and EP deliver useful information to select those patients who develop malignant edema.