Bert Bosche

Spreading depolarizations occur in human ischemic stroke with high incidence

Cortical spreading depression (CSD) and periinfarct depolarization (PID) have been shown in various experimental models of stroke to cause secondary neuronal damage and infarct expansion. For decades it has been questioned whether CSD or PID occur in human ischemic stroke. Here, we describe CSD and PID in patients with malignant middle cerebral artery infarction detected by subdural electrocorticography (ECoG).

Prediction of Malignant Course in MCA Infarction by PET and Microdialysis

BACKGROUND AND PURPOSE To predict malignant course in patients with large middle cerebral artery (MCA) infarction, we combined PET imaging and neuromonitoring, including microdialysis. METHODS Thirty-four patients with stroke of >50% of the MCA territory in early cerebral CT scan were included. Probes for microdialysis and measurement of intracranial pressure and tissue oxygen pressure (Pto2) were placed into the ipsilateral frontal lobe. PET was performed with 11C-flumazenil to assess CBF and irreversible neuronal damage. RESULTS PET measurements within 24 hours after stroke showed larger volumes of ischemic core (mean, 144.5 versus 62.2 cm3) and larger volumes of irreversible neuronal damage (157.9 versus 47.0 cm3) in patients with malignant course (ie, edema formation with midline shift) than in patients with benign course. Mean cerebral blood flow values within the ischemic core were significantly lower and the volume of the ischemic penumbra was smaller in the malignant than in the benign group. In patients with malignant course, cerebral perfusion pressure dropped to <50 to 60 mm Hg 22 to 72 hours (mean, 52.0 hours) after onset of symptoms; subsequently, Pto2 dropped and glutamate increased, indicating secondary ischemia. Maximal changes in the monitored variables reached significant levels for glutamate, aspartate, GABA, glycerol, lactate-to-pyruvate ratio, hypoxanthine, intracranial pressure, cerebral perfusion pressure, and Pto2. CONCLUSIONS PET allowed prediction of malignant MCA infarction within the time window suggested for hemicraniectomy. Neuromonitoring helped to classify the clinical courses by characterizing pathophysiological sequelae of malignant edema formation. In contrast to PET, however, it did not predict fatal outcome early enough for successful implementation of invasive therapies.

Recurrent Spreading Depolarizations after Subarachnoid Hemorrhage Decreases Oxygen Availability in Human Cerebral Cortex

Delayed ischemic neurological deficit (DIND) contributes to poor outcome in subarachnoid hemorrhage (SAH) patients. Because there is continuing uncertainty as to whether proximal cerebral artery vasospasm is the only cause of DIND, other processes should be considered. A potential candidate is cortical spreading depolarization (CSD)‐induced hypoxia. We hypothesized that recurrent CSDs influence cortical oxygen availability.

Identification and Clinical Impact of Impaired Cerebrovascular Autoregulation in Patients With Malignant Middle Cerebral Artery Infarction

Background and Purpose— To study cerebrovascular autoregulation and its impact on clinical course in patients with impending malignant middle cerebral artery infarction, we used invasive multimodal neuromonitoring, including measurement of cerebral perfusion pressure, tissue oxygen pressure, and microdialysis. Methods— Fifteen patients with a stroke that involved >50% of the middle cerebral artery territory were included. Probes were placed into the ipsilateral frontal lobe. Autoregulation was assessed by calculation of the cerebral perfusion pressure–oxygen reactivity index (COR) and the correlation coefficient (R) of cerebral perfusion pressure and tissue oxygen pressure at 24 and 72 hours after stroke. Results— COR and R at 24 hours after stroke were higher in the 8 patients with a malignant course (ie, massive edema formation) compared with the 7 patients with a benign course (COR, 1.99±1.46 versus 0.68±0.29; R, 0.49±0.28 versus 0.06±0.31; P<0.05), indicating impaired autoregulation in the malignant course group. At 72 hours, further increases in COR and R were observed in the malignant course group in contrast to the benign course group with stable values over time (COR, 3.31±2.38 versus 0.75±0.31; R, 0.75±011 versus 0.36±0.27; P<0.05). With a COR of 0.99, a cutoff value for prediction of a malignant course was found. The lactate-pyruvate ratio was higher in patients with a malignant compared with a benign course at both time points. COR, R, and the lactate-pyruvate ratio showed significant correlations with outcome parameters as a midline shift on cranial computed tomography and score on the modified Rankin scale after 3 months. Conclusions— We found early impairment of cerebrovascular autoregulation in peri-infarct tissue of patients who developed malignant brain edema, whereas autoregulation was preserved in patients with a benign course. Impaired cerebral autoregulation seems to play a key role for development of a malignant course and might serve as a predictive marker. Impaired cerebral autoregulation also accentuates the need for consequent adjustment of cerebral perfusion pressure in patients with impaired autoregulation.

Extracellular Concentrations of Non–Transmitter Amino Acids in Peri-Infarct Tissue of Patients Predict Malignant Middle Cerebral Artery Infarction

Background and Purpose— Space-occupying brain edema is a life-threatening complication in patients with large middle cerebral artery (MCA) infarction. To determine predictors of this detrimental process, we investigated alterations of extracellular non–transmitter amino acid concentrations in peri-infarct tissue. Methods— Thirty-one patients with infarctions covering >50% of the MCA territory in early cranial CT scans were included in the study. Probes for microdialysis, intracranial pressure, and tissue oxygen pressure were placed into the noninfarcted ipsilateral frontal lobe. Positron emission tomography imaging was performed in 16 of these patients to measure cerebral blood flow in the tissue around the neuromonitoring probes. Results— Fourteen of the 31 patients developed a malignant MCA infarction, and 17 did not. The patients in the malignant group had significantly lower extracellular concentrations of non–transmitter amino acids than those in the benign group in the first 12 hours of neuromonitoring. At this time, CBF values determined in regions of interest around the probes by positron emission tomography and tissue oxygen pressure showed that the monitored tissues were not yet infarcted, and no differences in transmitter amino acids concentrations were found between the 2 groups. Furthermore, extracellular concentrations of non–transmitter amino acids were negatively correlated with size of infarction. Conclusions— We assume that reduction of non–transmitter amino acid concentrations reflects an expansion of the extracellular space by vasogenic edema formation in peri-infarct tissue of patients with malignant MCA infarction. Our findings facilitate early prediction of malignant edema formation and may help to increase knowledge of the pathophysiology of the peri-infarct zone of large MCA infarction.

Early electroencephalography in acute ischemic stroke: Prediction of a malignant course?

Objective: In patients with large middle cerebral artery (MCA) infarction space occupying brain edema may lead to a malignant course with up to 80% mortality under conservative treatment. As interventional treatment strategies must be started before the deterioration occurs predictors of a malignant course are necessary. Patients and methods: This study reports on the results of early electroencephalography (EEG) within 24 h after onset of stroke in 25 patients suffering a large MCA infarct (12 patients with a malignant and 13 with a non-malignant course). EEG analysis was performed according well-established indicators for focal as well as global changes. Results: Our findings indicate that the absence of delta activity and the presence of theta and fast beta frequencies within the focus predict a benign course (p < 0.05), whereas diffuse generalized slowing and slow delta activity in the ischemic hemisphere may point to a malignant course.

The Severity of Ischemia Determines and Predicts Malignant Brain Edema in Patients with Large Middle Cerebral Artery Infarction

Background: In order to determine the impact of the severity of ischemia on malignant edema formation, we investigated various degrees of perfusional deficit by 11C-flumazenil PET in patients with large middle cerebral artery (MCA) infarction. Methods: 17 patients with large MCA stroke were included. Cerebral blood flow (CBF) was measured 15.9 ± 6.4 h after the ictus. Patients were divided into a malignant (n = 9) and a benign group (n = 8) as a function of their clinical courses and edema. Edema was measured as maximal midline shift on follow-up CTs. Total hypoperfusion volume was divided into different subvolumes according to the degree of CBF reduction. Results: Subvolumes of severe ischemia relative to total ischemic area were significantly larger in the malignant group than in the benign group and were significantly correlated with edema formation. The highest correlation and best predictive values for edema formation with a sensitivity, specificity, and a positive and negative predictive value of 100% were found for subvolumes with severe ischemia. Correlation coefficients and prediction decreased for subvolumes with less severe perfusional deficit, pointing to the risk of misclassifying patients when relying on the volume of total perfusional deficit alone. Conclusions: Malignant MCA infarction seems to be determined more by the volume of severe perfusional deficit than that of total perfusional deficit. Assessment of severely ischemic areas allows prediction of malignant edema formation and might help to select candidates for hemicraniectomy.

Sustained neurological recovery induced by resveratrol is associated with angioneurogenesis rather than neuroprotection after focal cerebral ischemia

According to the French paradox, red wine consumption reduces the incidence of vascular diseases even in the presence of highly saturated fatty acid intake. This phenomenon is widely attributed to the phytoalexin resveratrol, a red wine ingredient. Experimental studies suggesting that resveratrol has neuroprotective properties mostly used prophylactic delivery strategies associated with short observation periods. These studies did not allow conclusions to be made about resveratrols therapeutic efficacy post-stroke. Herein, we systematically analyzed effects of prophylactic, acute and post-acute delivery of resveratrol (50mg/kg) on neurological recovery, tissue survival, and angioneurogenesis after focal cerebral ischemia induced by intraluminal middle cerebral artery occlusion in mice. Over an observation period of four weeks, only prolonged post-acute resveratrol delivery induced sustained neurological recovery as assessed by rota rod, tight rope and corner turn tests. Although prophylactic and acute resveratrol delivery reduced infarct volume and enhanced blood-brain-barrier integrity at 2 days post-ischemia by elevating resveratrols downstream signal sirtuin-1, increasing cell survival signals (phosphorylated Akt, heme oxygenase-1, Bcl-2) and decreasing cell death signals (Bax, activated caspase-3), a sustained reduction of infarct size on day 28 was not observed in any of the three experimental conditions. Instead, enhanced angiogenesis and neurogenesis were noted in animals receiving post-acute resveratrol delivery, which were associated with elevated concentrations of GDNF and VEGF in the brain. Thus, sustained neurological recovery induced by resveratrol depends on successful brain remodeling rather than structural neuroprotection. The recovery promoting effect of delayed resveratrol delivery opens promising perspectives for stroke therapy.

Lithium prevents early cytosolic calcium increase and secondary injurious calcium overload in glycolytically inhibited endothelial cells

Cytosolic free calcium concentration ([Ca(2+)]i) is a central signalling element for the maintenance of endothelial barrier function. Under physiological conditions, it is controlled within narrow limits. Metabolic inhibition during ischemia/reperfusion, however, induces [Ca(2+)]i overload, which results in barrier failure. In a model of cultured porcine aortic endothelial monolayers (EC), we addressed the question of whether [Ca(2+)]i overload can be prevented by lithium treatment. [Ca(2+)]i and ATP were analysed using Fura-2 and HPLC, respectively. The combined inhibition of glycolytic and mitochondrial ATP synthesis by 2-desoxy-d-glucose (5mM; 2-DG) plus sodium cyanide (5mM; NaCN) caused a significant decrease in cellular ATP content (14±1 nmol/mg protein vs. 18±1 nmol/mg protein in the control, n=6 culture dishes, P<0.05), an increase in [Ca(2+)]i (278±24 nM vs. 71±2 nM in the control, n=60 cells, P<0.05), and the formation of gaps between adjacent EC. These observations indicate that there is impaired barrier function at an early state of metabolic inhibition. Glycolytic inhibition alone by 10mM 2-DG led to a similar decrease in ATP content (14±2 nmol/mg vs. 18±1 nmol/mg in the control, P<0.05) with a delay of 5 min. The [Ca(2+)]i response of EC was biphasic with a peak after 1 min (183±6 nM vs. 71±1 nM, n=60 cells, P<0.05) followed by a sustained increase in [Ca(2+)]i. A 24-h pre-treatment with 10mM of lithium chloride before the inhibition of ATP synthesis abolished both phases of the 2-DG-induced [Ca(2+)]i increase. This effect was not observed when lithium chloride was added simultaneously with 2-DG. We conclude that lithium chloride abolishes the injurious [Ca(2+)]i overload in EC and that this most likely occurs by preventing inositol 3-phosphate-sensitive Ca(2+)-release from the endoplasmic reticulum. Though further research is needed, these findings provide a novel option for therapeutic strategies to protect the endothelium against imminent barrier failure.

Occurrence and recurrence of spontaneous chronic subdural haematoma is associated with a factor XIII deficiency

OBJECTIVE In some patients, chronic subdural haematoma (cSDH) appears to occur spontaneously with frequent re-bleeding events. The pathophysiology of this phenomenon is still poorly understood. Because coagulation factor XIII (FXIII) is known to be involved in vascular integrity, endothelial barrier function and wound healing, we evaluated the role of FXIII in spontaneous cSDH. METHODS We prospectively scrutinised the origin of cSDH in 117 patients and identified a subgroup of patients suffering from spontaneous cSDH who were included in this study. We analysed the plasma activity of FXIII and standard coagulation parameters and compared these data to age- and sex-matched healthy controls. We assessed the occurrence of re-bleeding events using clinical and imaging data and compared FXIII activity in patients with and without re-bleeding events. RESULTS Out of 117 cSDH patients, 18 individuals suffered from spontaneous cSDH in this study. The patients with spontaneous cSDH showed significantly lower FXIII activity than the control group (65% [52.75, 80.25] (median [IQR]) vs. 93% [81, 111], P=0.001), whereas standard coagulation parameters did not differ significantly between the groups. Six patients developed re-bleeding events after haematoma evacuation, and these patients expressed significantly lower FXIII activity compared to the other 12 patients (47.5% [33.5, 64] vs. 78.5% [58, 87], P=0.005). The patient group with FXIII≤68.5% differed significantly from the group with FXIII>68.5% when categorised by the occurrence of re-bleeding events (n=6/9 vs. n=0/9, P=0.009). This cut-off value predicted the re-bleeding events with a sensitivity of 100% and a specificity of 75% (positive predictive value: 66%, negative predictive value: 100%). CONCLUSION FXIII deficiency may play a pathophysiological role in spontaneous cSDH, so we suggest investigating FXIII activity because it may predict re-bleeding events after treatment. In individuals with considerably low FXIII activity, FXIII substitution may mitigate the chronic nature of this disease.