Progressive change in cerebral blood flow during the first three weeks after subarachnoid hemorrhage

Fluid metabolic pathways after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating cerebrovascular disease with high mortality and morbidity. In recent years, a large number of studies have focused on the mechanism of early brain injury (EBI) and delayed cerebral ischemia (DCI), including vasospasm, neurotoxicity of hematoma and neuroinflammatory storm, after aSAH. Despite considerable efforts, no novel drugs have significantly improved the prognosis of patients in phase III clinical trials, indicating the need to further re-examine the multifactorial pathophysiological process that occurs after aSAH. The complex pathogenesis is reflected by the destruction of the dynamic balance of the energy metabolism in the nervous system after aSAH, which prevents the maintenance of normal neural function. This review focuses on the fluid metabolic pathways of the central nervous system (CNS), starting with ruptured aneurysms, and discusses the dysfunction of blood circulation, cerebrospinal fluid (CSF) circulation and the glymphatic system during disease progression. It also proposes a hypothesis on the metabolic disorder mechanism and potential therapeutic targets for aSAH patients.

Perioperative Management of Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage is an acute neurologic emergency. Prompt definitive treatment of the aneurysm by craniotomy and clipping or endovascular intervention with coils and/or stents is needed to prevent rebleeding. Extracranial manifestations of aneurysmal subarachnoid hemorrhage include cardiac dysfunction, neurogenic pulmonary edema, fluid and electrolyte imbalances, and hyperglycemia. Data on the impact of anesthesia on long-term neurologic outcomes of aneurysmal subarachnoid hemorrhage do not exist. Perioperative management should therefore focus on optimizing systemic physiology, facilitating timely definitive treatment, and selecting an anesthetic technique based on patient characteristics, severity of aneurysmal subarachnoid hemorrhage, and the planned intervention and monitoring. Anesthesiologists should be familiar with evoked potential monitoring, electroencephalographic burst suppression, temporary clipping, management of external ventricular drains, adenosine-induced cardiac standstill, and rapid ventricular pacing to effectively care for these patients.

Temporal Dynamics of Cerebral Blood Flow During the Acute Course of Severe Subarachnoid Hemorrhage Studied by Bedside Xenon-Enhanced CT

Background

Compromised cerebral blood flow (CBF) is a crucial factor in delayed cerebral ischemia after subarachnoid hemorrhage (SAH). Repeated measurement of CBF may improve our understanding of the temporal dynamics following SAH. The aim of this study was to assess CBF at different phases of the acute course in poor-grade SAH patients, hypothesizing more pronounced disturbances at day 4–7, and that the initial level of CBF determines the following course of CBF.

Methods

Mechanically ventilated SAH patients were scheduled for bedside measurement of regional and global cortical CBF at day 0–3, 4–7, and 8–12, using xenon-enhanced computed tomography in a mobile setup. Patients were dichotomized depending on high or low initial global cortical CBF and cutoff level 30 ml/100 g/min.

Results

Eighty-one patients were included, and 51 had measurements at day 0–3 and 4–7. In patients with high initial CBF, the level was unchanged at day 4–7; 37.7 (IQR 32.6–46.7) ml/100 g/min versus 36.8 (IQR 29.5–44.8). The low-CBF group showed a slight increase from 23.6 (IQR 21.0–28.1) ml/100 g/min to 28.4 (IQR 22.7–38.3) (P = 0.025), still markedly lower than the high-CBF group (P = 0.016). In the low-CBF group, CBF increased in patients who received hypertension, hypervolemia, and hemodilution (HHH therapy) but remained low in standard treated patients. For the subset of 27 patients examined also at day 8–12, the differences depending on initial CBF level were no longer statistically significant. Among patients with still low CBF at day 4–7, the proportion who had poor short-term outcome was 55% compared to 35% (n.s.) for patients with high CBF.

Conclusions

CBF studied in poor-grade SAH patients at large did not show any statistically significant changes over time. Stratifying patients by high or low initial CBF and whether HHH therapy was given revealed an association between low initial CBF and persistent low CBF at day 4–7. These findings may be of clinical relevance in managing SAH patients with low early CBF.

Cytochrome P450 eicosanoids in cerebrovascular function and disease

Cytochrome P450 eicosanoids play important roles in brain function and disease through their complementary actions on cell-cell communications within the neurovascular unit (NVU) and mechanisms of brain injury. Epoxy- and hydroxyeicosanoids, respectively formed by cytochrome P450 epoxygenases and ω-hydroxylases, play opposing roles in cerebrovascular function and in pathological processes underlying neural injury, including ischemia, neuroinflammation and oxidative injury. P450 eicosanoids also contribute to cerebrovascular disease risk factors, including hypertension and diabetes. We summarize studies investigating the roles P450 eicosanoids in cerebrovascular physiology and disease to highlight the existing balance between these important lipid signaling molecules, as well as their roles in maintaining neurovascular homeostasis and in acute and chronic neurovascular and neurodegenerative disorders.

Aneurysmal Surgery in the Presence of Angiographic Vasospasm: An Outcome Assessment

Background and Purpose:

The timing of aneurysmal surgery for patients presenting within the period at risk for vasospasm (VS) is controversial. The goal of this study is to review our experience of surgically treated patients in the presence of angiographic VS.

Materials and Methods:

From 1990-2004, 894 consecutive patients presented with an aneurysmal subarachnoid hemorrhage (SAH) and were treated with a policy of early surgery. We retrospectively analyzed the patients that had pre-operative angiographic VS. In this study, symptomatic VS was diagnosed when a decreased level of consciousness and/or focal deficit occurred after SAH in the presence of angiographic VS without confounding factors. Functional outcome was assessed three months after SAH using the Glasgow Outcome Scale.

Results:

Of the 40 patients studied, 62.5% were in good clinical grade Hunt & Hess (H&H 1-2) on admission; 25%, intermediate grade (H&H 3); 12.5%, poor grade (H&H 4-5). Surgery was performed 24 hours or less after initial angiography in 87.5% of patients and less than 48 hours in 97.5%. Pre-operative symptomatic VS was diagnosed in 25%. Postoperatively, angiographic VS was documented in 87.2%. Of the 30% of patients that presented post-operative symptomatic VS, 66.7% also demonstrated pre-operative symptomatic VS. The functional outcome was favorable in 92.5% of the studied patients. Two deaths occurred in patients presenting pre-operative early radiological and symptomatic VS.

Conclusion:

Aneurysmal surgery, especially between 3-12 days following SAH, in the presence of asymptomatic pre-operative angiographic VS can be associated with a good outcome. Early surgery is not contra-indicated and might enable optimal treatment of VS.

Evidence that 20-HETE contributes to the development of acute and delayed cerebral vasospasm

Recent studies have indicated that arachidonic acid (AA) is metabolized by the cytochrome P450 4A (CYP4A) enzymes in cerebral arteries to produce 20-hydroxyeicosatetraenoic acid (20-HETE) and that this compound has effects on cerebral vascular tone that mimic those seen following subarachnoid hemorrhage (SAH). In this regard, 20-HETE is a potent constrictor of cerebral arteries that decreases the open state probability of Ca(2+)-activated K(+) channels through activation of protein kinase C (PKC). It increases the sensitivity of the contractile apparatus to Ca(2+) by activating PKC and rho kinase. The formation of 20-HETE is stimulated by angiotensin II (AII), endothelin, adenosine triphosphate (ATP) and serotonin, and inhibited by NO, CO and superoxide radicals. Inhibitors of the formation of 20-HETE block the myogenic response of cerebral arterioles to elevations in transmural pressure in vitro and autoregulation of cerebral blood flow (CBF) in vivo. 20-HETE also plays an important role in modulating the cerebral vascular responses to vasodilators (NO and CO) and vasoconstrictors (AII, endothelin, serotonin). Recent studies have indicated that the levels of 20-HETE in cerebrospinal fluid (CSF) increase in rats, dogs and human patients following SAH and that inhibitors of the synthesis of 20-HETE prevent the acute fall in CBF in rats and reverse delayed vasospasm in both dogs and rats. This review examines the evidence that an elevation in the production of 20-HETE contributes to the initial fall in CBF following SAH and the later development of delayed vasospasm.

Cerebral CT Perfusion in Patients with Perimesencephalic and Those with Aneurysmal Subarachnoid Hemorrhage

Background

The cause of perimesencephalic hemorrhage is unknown, but a venous source is suggested. If perimesencephalic hemorrhage is of venous origin, less elevation of the intracranial pressure and less perfusion deficits are expected than after aneurysmal subarachnoid hemorrhage.

Aims

We compared perfusion in the acute stage after perimesencephalic hemorrhage and aneurysmal subarachnoid hemorrhage.

Methods

We included 45 perimesencephalic hemorrhage patients and 45 aneurysmal subarachnoid hemorrhage patients, who were matched on clinical condition at admission and underwent computerized tomographic scanning <72 h after subarachnoid hemorrhage. Cerebral blood flow was assessed in 12 predefined regions of interest. Differences in cerebral blood flow values with corresponding 95% confidence intervals were calculated. Sub-group analyses were performed stratified on comparable amounts of blood and location of blood (posterior circulation aneurysms and additionally in infratentorial and supratentorial aneurysms).

Results

Cerebral blood flow was higher in perimesencephalic hemorrhage patients (mean: 63·8) than in aneurysmal subarachnoid hemorrhage patients (mean: 55·9; difference of means: −7·9 [95% confidence interval: −10·7 to −5·2]) and also in the sub-group with comparable amounts of blood (mean cerebral blood flow: 56·4; difference of means: −7·4 [95% confidence interval: −10·4 to −4·3]). Cerebral blood flow was comparable with perimesencephalic hemorrhage patients for the sub-group with posterior circulation aneurysms (difference of means: −0·7 [95% confidence interval: −5·2 to 3·8]); however, differences diverged after stratifying posterior circulation aneurysms into supratentorial (difference of means −3·9 [95% confidence interval: −9·3 to 1·4]) and infratentorial aneurysms (difference of means 3·0 [95% confidence interval: −2·8 to 8·8]).

Conclusion

Perimesencephalic hemorrhage patients have a higher cerebral blood flow than aneurysmal subarachnoid hemorrhage patients. The findings of this study further support a venous origin of bleeding in perimesencephalic hemorrhage patients. Future studies should further elaborate on cerebral blood flow in posterior circulation aneurysms.

The assessment of pathological changes in cerebral blood flow in hypertensive rats with stress-induced intracranial hemorrhage using Doppler OCT: Particularities of arterial and venous alterations/Die Beurteilung von pathologischen Veränderungen der Hirndurchblutung bei hypertensiven Ratten mit Stress-induzierten intrakraniellen Blutungen mittels Doppler-OCT: Besonderheiten von arteriellen und venösen Veränderungen

Hemorrhagic insult is a major source of morbidity and mortality in both adults and newborn babies in the developed countries. The mechanisms underlying the non-traumatic rupture of cerebral vessels are not fully clear, but there is strong evidence that stress, which is associated with an increase in arterial blood pressure, plays a crucial role in the development of acute intracranial hemorrhage (ICH), and alterations in cerebral blood flow (CBF) may contribute to the pathogenesis of ICH. The problem is that there are no effective diagnostic methods that allow for a prognosis of risk to be made for the development of ICH. Therefore, quantitative assessment of CBF may significantly advance the understanding of the nature of ICH. The aim of this study was to determine the particularities of alterations in arterial and venous cerebral circulation in hypertensive rats at different stages of stress-related development of ICH using three-dimensional Doppler optical coherence tomography (DOCT).

Experiments were performed in mongrel adult rats. To induce ICH, hypertensive rats underwent stress (effect of severe sound, 120 dB during 2 h). To induce the renal hypertension (two kidneys, one clip) the rats were clipped at the left renal artery with a silver clip. Seven weeks after clipping, the hypertensive rats were used in the experiment. The monitoring of CBF was performed in anesthetized rats with fixed heads using a commercially available swept source OCT system (OCS1300SS; Thorlabs) in the masked period of ICH (4 h after stress) and during ICH (24 h after stress).

It could be shown that in stressed rats, compared with non-stressed animals, the latent stage of stress-induced ICH (4 h after stress-off) is characterized by an increase in diameter of the superior sagittal vein with decrease in speed of the blood flow in the venous network, whereas no changes in the CBF in the arterial tree were found in this period. These facts suggest that the masked period of ICH is accompanied by decreasing venous outflow and the development of venous insufficiency. The incidence of ICH, 24 h after stress, is associated with progression of pathological alterations in cerebral venous circulation. All hypertensive rats with ICH demonstrated a greater increase in the diameter of the superior sagittal vein than stressed rats at the latent stage of ICH (in 2.5-fold,

In summary, using DOCT we have shown that the latent stage of stress-induced ICH is characterized by a decrease in venous outflow. The incidence of ICH is associated with the progression of pathological alterations in cerebral venous circulation that is accompanied by a decrease in blood flow in the arterial tree. The evaluation of cerebral venous insufficiency is an important diagnostic approach for the prognosis of the risk of developing cerebral hypotension and ICH.

The effect of vasospasm on cerebral perfusion: a colour duplex study of the extra- and intracranial cerebral arteries

To assess whether middle cerebral artery (MCA) vasospasm reduces the flow volume in the corresponding extracranial internal carotid artery (ICA) or global cerebral blood flow volume (CBFV) in subarachnoid haemorrhage (SAH) patients, a colour duplex ultrasound study of the intra- and extracranial cerebral arteries was performed. MCA vasospasm was defined as a time-averaged maximum flow velocity (TAMX) exceeding 120 cm/s. ICA flow volumes and CBFV, were compared in each patient at maximum TAMX recorded in one MCA ("maximum-vasospasm") and when TAMX in the same vessel was closest to mean reference values ("no-vasospasm"). Additionally, the CBFV course during the first 3 weeks after SAH was evaluated longitudinally. Data from age- and gender-matched healthy test persons served as control. In 28 patients with MCA vasospasm, 337 measurements were completed. Global CBFV was significantly reduced starting from day 3 after SAH. ICA flow volumes and CBFV were not different when comparing at "maximum-vasospasm" and "no-vasospasm". Compared with the control group, both were lower at either condition. Thus, in SAH patients, vasospasm even severe, in general does not further diminish ICA flow volumes and global CBFV, which are reduced already before the onset of vasospasm.

Risk profile of patients with poor-grade aneurysmal subarachnoid hemorrhage using early perfusion computed tomography

OBJECTIVE

To determine whether perfusion computed tomography (CT) is useful for identifying patients with poor-grade subarachnoid hemorrhage (SAH) with reversible etiologies and whether early obliteration in patients with poor-grade aneurysmal SAH leads to favorable outcomes.

METHODS

Patients with new-onset aneurysmal SAH in World Federation of Neurological Surgeons (WFNS) grade IV or V neurologic condition who had perfusion CT performed at admission were eligible for the study. The study retrospectively enrolled 38 patients seen between January 2007 and July 2009. The decision to perform an early obliteration was made by the family after a discussion with the neurosurgeons, neurointensivists, and interventional radiologists. The functional outcomes were correlated with the Glasgow Outcome Scale (GOS) at 6 months, and quantitative perfusion CT data were collected.

RESULTS

This study included 10 (26%) grade IV and 28 (74%) grade V patients. Favorable outcomes occurred in 19 (50%) patients, and 11 (29%) patients died. After a multivariate logistic regression analysis of the parameters, older age (odds ratio 1.104, P = 0.0317), bilateral prolonged mean transient time (MTT) at the thalami (odds ratio 4.155, P = 0.0362), and early obliteration (odds ratio 0.098, P = 0.003) were predictive of poor outcome.

CONCLUSIONS

Early bilateral prolonged MTT at the thalami and old age are associated with a poor outcome. Early obliteration benefits a significant portion of SAH patients.

Using CT perfusion during the early baseline period in aneurysmal subarachnoid hemorrhage to assess for development of vasospasm

INTRODUCTION

The aim of this study is to evaluate computed tomography perfusion (CTP) during admission baseline period (days 0-3) in aneurysmal subarachnoid hemorrhage (A-SAH) for development of vasospasm.

METHODS

Retrospective analysis was performed on A-SAH patients from Dec 2004 to Feb 2007 with CTP on days 0-3. Cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) maps were analyzed for qualitative perfusion deficits. Quantitative analysis was performed using region-of-interest placement to obtain mean CTP values. Development of vasospasm was determined by a multistage hierarchical reference standard incorporating both imaging and clinical criteria. Student's t test and threshold analysis were performed.

RESULTS

Seventy-five patients were included, 37% (28/75) were classified as vasospasm. Mean CTP values in vasospasm compared to no vasospasm groups were: CBF 31.90 ml/100 g/min vs. 39.88 ml/100 g/min (P < 0.05), MTT 7.12 s vs. 5.03 s (P < 0.01), and CBV 1.86 ml/100 g vs. 2.02 ml/100 g (P = 0.058). Fifteen patients had qualitative perfusion deficits with 73% (11/15) developed vasospasm. Optimal threshold for CBF is 24-25 mL/100 g/min with 91% specificity and 50% sensitivity, MTT is 5.5 s with 70% specificity and 61% sensitivity and CBV is 1.7 mL/100 g with 89% specificity and 36% sensitivity.

CONCLUSION

These initial results support our hypothesis that A-SAH patients who develop vasospasm may demonstrate early alterations in cerebral perfusion, with statistically significant CBF reduction and MTT prolongation. Overall, CTP has high specificity for development of vasospasm. Future clinical implications include using CTP during the baseline period for early identification of A-SAH patients at high risk for vasospasm to prompt robust preventative measures and treatment.

Clinical response to hypertensive hypervolemic therapy and outcome after subarachnoid hemorrhage

OBJECTIVE

Hypertensive hypervolemic therapy is widely used to treat symptomatic vasospasm after subarachnoid hemorrhage. Few data exist to support a relationship between early clinical response and mortality or functional outcome.

METHODS

In a prospective cohort of 580 subarachnoid hemorrhage patients, we studied 95 patients with acute symptomatic vasospasm who received stepwise volume expansion with crystalloid and/or 5% albumin solution followed by intravenous pressors to maintain systolic blood pressure between 180 and 220 mm Hg. We separately assessed the effects of volume expansion and induced hypertension on the neurological examination during the first 2 hours of each intervention. We used multivariate logistic regression analysis to calculate adjusted odds ratios assessing the relationship between clinical response to hypertensive hypervolemic therapy and 3-month outcome, as measured by the modified Rankin Scale.

RESULTS

Of 95 patients with symptomatic vasospasm, volume expansion was used in 94% (n = 89), of whom 43% had a clinical response; 85% of the patients (n = 81) received pressors, of whom 68% responded. Early clinical improvement attributable to either volume expansion or pressors was not related to the development of infarction on computed tomography, but response to either modality within 2 hours was independently protective against death (adjusted odds ratio, 0.03; P < 0.05) and death-or-severe-disability (modified Rankin Scale score, 4-6; adjusted odds ratio, 0.1; P < 0.05) after adjusting for age, Hunt-Hess grade, angioplasty, and aneurysm size.

CONCLUSION

Subarachnoid hemorrhage patients with symptomatic vasospasm who fail to demonstrate early clinical improvement in response to volume or pressor therapy are at high risk for death or disability. Urgent endovascular intervention in this high-risk patient cohort may be justified.

Neurointensive care is justified in elderly patients with severe subarachnoid hemorrhage--an outcome and secondary insults study

PURPOSE

The aim was to study the outcome and the occurrence of secondary brain insults in elderly patients with severe subarachnoid hemorrhage (SAH) in comparison to younger patients.

METHODS

Ninety-nine patients with severe SAH requiring a ventriculostomy and management at the neurointensive care unit with at least 120 h of multimodality monitoring data during the first 240 h following SAH were included. Data were continuously recorded for intracranial pressure (ICP), cerebral perfusion pressure, blood pressure, oxygen saturation, and temperature. Secondary insult levels were defined and quantified as percent of good monitoring time at insult level. Outcome according to the Glasgow Outcome Scale was evaluated at 6 months after the SAH. Age-dependent differences in occurrence of secondary insults and clinical characteristics were analyzed with multiple regression analysis.

RESULTS

Good recovery or moderate disability was achieved in 24.1% of the elderly and in 42.9% of the younger patients. The frequency of severe disability was 41.4% in the elderly and 37.1% in the younger patients. The occurrence of ICP insults was lower and the occurrence of hypertensive, hypotensive, and hypoxemic insults were higher in the elderly patients.

CONCLUSIONS

An independent outcome was achieved in a substantial proportion of the elderly with severe SAH, and the proportion of severe disability was not greater than among the younger patients, which justifies neurointensive care also in elderly patients. The occurrence of secondary insults was age dependent. Future studies of multimodality monitoring may provide age-specific secondary insult levels necessary for a tailored neurointensive care specific for elderly patients with severe SAH.

Does prophylactic postoperative hypervolemic therapy prevent cerebral vasospasm and improve clinical outcome after aneurysmal subarachnoid hemorrhage?

BACKGROUND

Delayed cerebral vasospasm is a common cause of morbidity and mortality after acute aneurysmal subarachnoid hemorrhage. Hypovolemia and fluid restriction are risk factors for delayed vasospasm; hypervolemic therapeutic approaches are commonly used in patients with subarachnoid hemorrhage to prevent and to treat cerebral vasospasm.

OBJECTIVE

To determine if postoperative prophylactic hypervolemic therapy prevents cerebral vasospasm and improves clinical outcome in patients with aneurysmal subarachnoid hemorrhage.

METHODS

The objective was addressed through the development of a structured critically appraised topic. This included a clinical scenario, structured question, search strategy, critical appraisal, results, evidence summary, commentary, and bottom line conclusions. Participants included consultant and resident neurologists, a medical librarian, clinical epidemiologists, and content experts in the field of vascular neurology.

RESULTS

One randomized controlled trial addressed the questions. There was no difference in the incidence of symptomatic cerebral vasospasm (20% each) or clinical outcome at 14 days and 3 months between the hypervolemic and normovolemic groups. Hypervolemic therapy also had no effect on measures of cerebral blood flow. A second quasi-randomized trial reached the same conclusions.

CONCLUSION

Available evidence is insufficient to support use of prophylactic hypervolemic therapy after surgery in patients with aneurysmal subarachnoid hemorrhage. Although completed studies may be insufficiently sensitive (underpowered) to detect a treatment effect, the magnitude of any as yet undetected benefit of prophylactic hypervolemic therapy is likely modest and its risks have not been systematically evaluated.

Neurological impairment in rats after subarachnoid hemorrhage--a comparison of functional tests

Functional outcome has become a key parameter for the determination of the efficacy of therapeutic interventions. Unfortunately, functional tests are not established for filament perforation induced subarachnoid hemorrhage (SAH). Therefore, we evaluated generally applied functional tasks for their potential to discriminate between various degrees of neuronal damage. Rats were subjected to SAH by an endovascular filament and were randomly assigned to controls treated with 0.9% NaCl, moderately neuroprotective therapy with 7.5% NaCl, and highly effective neuroprotection by 7.5% NaCl+6% dextran 70 (HSD). Functional deficit was quantified daily using beam balance task, prehensile traction task, rotarod, a 6-point motor function score and a general neurological 100-point score. Only the HSD group exhibited significantly more surviving neurons at postoperative day 7. Despite significant variations in histomorphometry, beam balance, prehensile traction and rotarod failed to distinguish between groups. On the other hand, the 100-point neuroscore showed improved neurological recovery on postoperative day 1 for HSD. The 100-point neuroscore failed to discriminate between treatment arms at later time points and therefore seems to reflect predominantly early neurological dysfunction. In conclusion, the results of pure motor tasks after experimental SAH in rats should be carefully interpreted. The integration of a test regimen to examine long term cognitive deficits after rat SAH might be valuable to gain additional information about the functional consequences of morphological damage.

Vasospasm probability index: a combination of transcranial doppler velocities, cerebral blood flow, and clinical risk factors to predict cerebral vasospasm after aneurysmal subarachnoid hemorrhage

OBJECT

The goal in this study was to create an index (vasospasm probability index [VPI]) to improve diagnostic accuracy for vasospasm after subarachnoid hemorrhage (SAH).

METHODS

Seven hundred ninety-five patients in whom aneurysmal SAH was demonstrated by computed tomography, and in whom one or more intracranial aneurysms had been diagnosed, underwent transcranial Doppler (TCD) studies between April 1998 and January 2000. In 154 patients angiography was performed within 24 hours of the TCD examination, and in 75 133Xe cerebral blood flow (CBF) studies were obtained the same day. Seven cases were excluded because of a limited sonographic window. Forty-one women (60.3%) and 27 men (39.7%) between the ages of 35 and 84 years (58.0 +/- 13.2 years [mean +/- standard deviation]) were included. Clinical characteristics analyzed included age, sex, Hunt and Hess grade, Fisher grade, days after SAH, day of treatment, type of treatment (coil embolization, surgical clip occlusion, or conservative treatment), smoking history, and hypertension history. Lindegaard ratios and spasm indexes (TCD velocities/hemispheric CBF) were calculated bilaterally. Digital subtraction angiography images were measured at specific points of interest. Sensitivity, specificity, predictive values, and global accuracy of the different tests were calculated. Logistic regression was used to evaluate the possible predictive factors, and the coefficients of the logistic regression were integrated to create the VPI.

RESULTS

In 18 patients (26.5%) symptomatic vasospasm was diagnosed, and 33 (48.5%) had angiographic evidence of vasospasm. For TCD velocities above 120 cm/second at the middle cerebral artery, the global accuracy was 81.1% for the diagnosis of clinical vasospasm and 77.2% for angiographic vasospasm. For a Lindegaard ratio higher than 3.0, the accuracy was 85% for clinical vasospasm and 83.2% for angiographic vasospasm. A spasm index higher than 3.5 had an accuracy of 82.0% for the diagnosis of clinical vasospasm and 81.6% for angiographic vasospasm. The selected model for estimation of clinical vasospasm included Fisher grade, Hunt and Hess grade, and spasm index. The VPI had a global accuracy of 92.9% for clinical vasospasm detection. For diagnosis of angiographic vasospasm, the model included Fisher grade, Hunt and Hess grade, and Lindegaard ratio. The VPI achieved a global accuracy of 89.9% for angiographic vasospasm detection.

CONCLUSIONS

The use of TCD velocities, Lindegaard ratio, and spasm index independently is of limited value for the diagnosis of clinical and angiographic vasospasm. The combination of predictive factors associated with the development of vasospasm in the new index reported here has a significantly superior accuracy compared with the independent tests and may become a valuable tool for the clinician to evaluate the individual probability of cerebral vasospasm after aneurysmal SAH.

Effects of hypervolemia and hypertension on regional cerebral blood flow, intracranial pressure, and brain tissue oxygenation after subarachnoid hemorrhage

OBJECTIVE

Hypertensive, hypervolemic, hemodilution therapy (triple-H therapy) is a generally accepted treatment for cerebral vasospasm after subarachnoid hemorrhage. However, the particular role of the three components of triple-H therapy remains controversial. The aim of the study was to investigate the influence of the three arms of triple-H therapy on regional cerebral blood flow and brain tissue oxygenation.

DESIGN

Animal research and clinical intervention study.

SETTING

Surgical intensive care unit of a university hospital.

SUBJECTS AND PATIENTS

Experiments were carried out in five healthy pigs, followed by a clinical investigation of ten patients with subarachnoid hemorrhage.

INTERVENTIONS

First, we investigated the effect of the three components of triple-H therapy under physiologic conditions in an experimental pig model. In the next step we applied the same study protocol to patients following aneurysmal subarachnoid hemorrhage. Mean arterial pressure, intracranial pressure, cerebral perfusion pressure, cardiac output, regional cerebral blood flow, and brain tissue oxygenation were continuously recorded. Intrathoracic blood volume and central venous pressure were measured intermittently. Vasopressors and/or colloids and crystalloids were administered to stepwise establish the three components of triple-H therapy.

MEASUREMENTS AND MAIN RESULTS

In the animals, neither induced hypertension nor hypervolemia had an effect on intracranial pressure, brain tissue oxygenation, or regional cerebral blood flow. In the patient population, induction of hypertension (mean arterial pressure 143 +/- 10 mm Hg) resulted in a significant (p < .05) increase of regional cerebral blood flow and brain tissue oxygenation at all observation time points. In contrast, hypervolemia/hemodilution (intrathoracic blood volume index 1123 +/- 152 mL/m) induced only a slight increase of regional cerebral blood flow while brain tissue oxygenation did not improve. Finally, triple-H therapy failed to improve regional cerebral blood flow more than hypertension alone and was characterized by the drawback that the hypervolemia/hemodilution component reversed the effect of induced hypertension on brain tissue oxygenation.

CONCLUSIONS

Vasopressor-induced elevation of mean arterial pressure caused a significant increase of regional cerebral blood flow and brain tissue oxygenation in all patients with subarachnoid hemorrhage. Volume expansion resulted in a slight effect on regional cerebral blood flow only but reversed the effect on brain tissue oxygenation. In view of the questionable benefit of hypervolemia on regional cerebral blood flow and the negative consequences on brain tissue oxygenation together with the increased risk of complications, hypervolemic therapy as a part of triple-H therapy should be applied with utmost caution.

Convenience of the computed tomography perfusion method for cerebral vasospasm detection after subarachnoid hemorrhage

BACKGROUND

Vasospasm is a frequent complication in the early clinical course after SAH. Although various methods have been used to measure cerebral perfusion including PET, SPECT, xenon CT, and TCD, these require the patients to remain still for a long period. In addition, TCD is operator dependent. The current study aimed to clarify the convenience of CTP for the assessment of cerebral vasospasm caused by SAH.

METHODS

Nineteen patients with SAH aged 44 to 85 years (mean, 64 years) were recruited with informed consent. All patients were treated with the prevailing therapy and underwent CTP on days 6 to 9, followed by DSA and 3D-CTA to detect cerebral vasospasm. In each patient, we measured the MTT, CBF, and CBV. The reliability of CTP data was verified by comparing the data from CTP and xenon CT between the controls, and the average was calculated. Six ROIs were located symmetrically in the frontal, temporal, and occipital lobes.

RESULTS

An MTT value more than 20% greater than the average indicated the progression of cerebral vasospasm, and patients with vasospasm-related infarcts exhibited an MTT more than 47% greater than the mean value (odds ratio, 50). Patients with delayed cerebral infarcts had a significantly lower mean CBF and CBV and higher MTT than patients who did not develop CI.

CONCLUSION

Significant correlations between MTT and CBF values and neurovascular findings were obtained. Computed tomography perfusion can be performed in a short time and on a regular basis, and it therefore has the potential to identify cerebral vasospasm because of SAH.

Characterization of microvascular basal lamina damage and blood-brain barrier dysfunction following subarachnoid hemorrhage in rats

Vasogenic brain edema is one of the major determinants for mortality following subarachnoid hemorrhage (SAH). Although the formation of vasogenic brain edema occurs on the microvascular level by opening of endothelial tight junctions and disruption of the basal lamina, microvascular changes following experimental SAH are poorly characterized. The aim of the present study was therefore to investigate the time course of blood-brain barrier (BBB) dysfunction and basal lamina damage following SAH as a basis for the better understanding of the pathophysiology of SAH. SAH was induced in Sprague-Dawley rats by an endovascular filament. Animals were sacrificed 6, 24, 48, and 72 h thereafter (n=9 per group). Microvascular basal lamina damage was quantified by collagen type IV immunostaining. Western blotting was used to quantify collagen IV protein content and bovine serum albumin (BSA) extravasation as a measure for basal lamina damage and blood-brain barrier disruption, respectively. BSA Western blot revealed significant (p<0.05) BBB opening in the cerebral cortex ipsilateral to the hemorrhage beginning 6 h and peaking 48 h after SAH. Significant (p<0.05) basal lamina damage occurred with gradual increase from 24 to 72 h. Basal lamina damage correlated significantly with BBB dysfunction (r=-0.63; p=0.0001). Microvascular damage as documented by collagen IV degradation and albumin extravasation is a long lasting and ongoing process following SAH. Due to its delayed manner microvascular damage may be prone for therapeutic interventions. However, further investigations are needed to determine the molecular mechanisms responsible for basal lamina degradation and hence damage of the microvasculature following SAH.

Cerebrovascular Dynamics With Head-of-Bed Elevation in Patients With Mild or Moderate Vasospasm After Aneurysmal Subarachnoid Hemorrhage

• Background In patients with aneurysmal subarachnoid hemorrhage, elevation of the head of the bed during vasospasm has been limited in an attempt to minimize vasospasm or its sequelae or both. Consequently, some patients have remained on bed rest for weeks.

• Objectives To determine how elevations of the head of the bed of 20° and 45° affect cerebrovascular dynamics in adult patients with mild or moderate vasospasm after aneurysmal subarachnoid hemorrhage and to describe the response of mild or moderate vasospasm to head-of-bed elevations of 20° and 45° with respect to variables such as grade of subarachnoid hemorrhage and degree of vasospasm.

• Methods A within-patient repeated-measures design was used. The head of the bed was positioned in the sequence of 0°-20°-45°-0° in 20 patients with mild or moderate vasospasm between days 3 and 14 after aneurysmal subarachnoid hemorrhage. Continuous transcranial Doppler recordings were obtained for 2 to 5 minutes after allowing approximately 2 minutes for stabilization in each position.

• ResultsNo patterns or trends indicated that having the head of the bed elevated increases vasospasm. As a group, there were no significant differences within patients at the different positions of the head of the bed. Utilizing repeated-measures analysis of variance, P values ranged from .34 to .97, well beyond .05. No neurological deterioration occurred.

• Conclusions In general, elevation of the head of the bed did not cause harmful changes in cerebral blood flow related to vasospasm.

Cerebral perfusion heterogeneity and complexity in patients with acute subarachnoid haemorrhage

BACKGROUND

The pathophysiological mechanisms of impaired perfusion during acute subarachnoid haemorrhage (SAH) are incompletely understood. Cerebral perfusion at the micro vascular level can be assessed by single photon emission computed tomography (SPECT). We used a SPECT approach with 99mTc-ECD to measure the cerebral perfusion heterogeneity and complexity in patients with acute aneurysmal SAH or perimesencephalic non-aneurysmal SAH (PNSAH).

METHODS

The perfusion SPECT data of 61 patients with aneurysmal SAH, 18 patients with PNSAH, and 20 healthy control subjects were analysed by dividing the brain into 384 regions of interest. The magnitude of spatial perfusion heterogeneity was assessed by calculating the relative dispersion (RD=coefficient of variation). The fractal dimension (FD) was used to describe the overall complexity of global cerebral perfusion.

RESULTS

Patients with aneurysmal SAH (RD=11.30+/-2.17, P<0.001) and PNSAH (10.38+/-2.27, P=0.023) had a higher perfusion heterogeneity than control subjects (8.69+/-0.80). Patients with aneurysmal SAH tended to have a higher perfusion heterogeneity than patients with PNSAH (P=0.061). Also the overall complexity of cerebral perfusion was decreased in aneurysmal SAH (FD=1.11+/-0.06, P<0.001) and PNSAH (1.11+/-0.06, P=0.004) as compared with control subjects (1.17+/-0.06). Acute SAH causes increased regional cerebral perfusion heterogeneity and decreased overall complexity of global cerebral perfusion.

CONCLUSION

Non-invasive assessment of cerebral perfusion characteristics is feasible with SPECT and fractal analysis in patients with acute SAH and may help evaluating micro vascular function in SAH.

Reversal of delayed vasospasm by an inhibitor of the synthesis of 20-HETE

This study characterized the time course of changes in cerebral blood flow (CBF) and vascular diameter in a dual-hemorrhage model of subarachnoid hemorrhage (SAH) in rats and examined whether acute blockade of the synthesis of 20-hydroxyeicosatetraenoic acid (20-HETE) with N-(3-chloro-4-morpholin-4-yl)phenyl-N'-hydroxyimido formamide (TS-011) can reverse delayed vasospasm in this model. Rats received an intracisternal injection of blood (0.4 ml) on day 0 and a second injection 2 days later. CBF was sequentially measured using laser-Doppler flowmetry, and the diameters of the cerebral arteries were determined after filling the cerebral vasculature with a casting compound. CBF fell to 67% of control after the first intracisternal injection of blood but returned to a value near control 24 h later. CBF again fell to 63% of control after a second intracisternal injection of blood and remained 30% below control for 5 days. The fall in CBF after the second intracisternal injection of blood was associated with a sustained 30% reduction in the diameters of the middle cerebral, posterior communicating, and basilar arteries. Acute blockade of the synthesis of 20-HETE with TS-011 (0.1 mg/kg i.v.), 5 days after the second SAH, increased the diameters of the cerebral arteries, and CBF returned to control. These results indicate that the rats develop delayed vasospasm after induction of the dual-hemorrhage model of SAH and that blockade of the synthesis of 20-HETE fully reverses cerebral vasospasm in this model. They also implicate 20-HETE in the development and maintenance of delayed cerebral vasospasm.

Trends in monitoring patients with aneurysmal subarachnoid haemorrhage

After aneurysmal subarachnoid haemorrhage (SAH), the clinical outcome depends upon the primary haemorrhage and a number of secondary insults in the acute post-haemorrhagic period. Some secondary insults are potentially preventable but prevention requires prompt recognition of cerebral or systemic complications. Currently, several neuro-monitoring techniques are available; this review describes the most frequently used techniques and discusses indications for their use, and their value in diagnosis and prognosis. None of the techniques, when considered in isolation, has proved sufficient after SAH. Furthermore, the use of multi-modality monitoring is hampered by a lack of clinical studies that identify combinations of specific techniques in terms of clinical information and reliability. However, ischaemia at the tissue level can be detected by intracerebral microdialysis technique. Used together with the conventional monitoring systems, for example intracranial pressure measurements, transcranial Doppler ultrasound and modern neuro-imaging, direct assessment of biochemical markers by intracerebral microdialysis is promising in the advancement of neurointensive care of patients with SAH. A successfully implemented monitoring system provides answers but it also raises valuable new questions challenging our current understanding of the brain injury after SAH.

Computed Tomographic Perfusion in the Management of Aneurysmal Subarachnoid Hemorrhage: New Application of an Existent Technique

OBJECTIVE:

Cerebral blood flow (CBF) alterations are common after aneurysmal subarachnoid hemorrhage (SAH). Treatment of delayed cerebral ischemia in this setting depends on timely and accurate diagnosis. Techniques to measure cerebral blood flow are useful and important. Computed tomographic (CT) perfusion imaging is a technique for the measurement of CBF, cerebral blood volume, and time to peak. It is a fast and inexpensive brain imaging modality that offers promise in the management of patients with SAH.

METHODS:

CT perfusion imaging was performed in 10 patients with aneurysmal SAH when neurological changes raised suspicions of cerebral ischemia. Quantitative values for CBF, cerebral blood volume, and time to peak were obtained in each study. The case history, CT perfusion results, and an analysis of how patient management was influenced are presented for each patient.

RESULTS:

A total of 17 CT perfusion studies were performed. Five studies showed evidence of cerebral ischemia, leading to endovascular treatment of vasospasm. Eight studies excluded cerebral ischemia, and two studies identified cerebral hyperemia, resulting in adjustments in hyperdynamic therapy. CT perfusion was used to help predict a poor prognosis and withhold aggressive intervention in two patients with poor Hunt and Hess grades. Time-to-peak values identified regions of cerebral ischemia more readily than CBF or cerebral blood volume values.

CONCLUSION:

CT perfusion imaging can be used to identify patients with delayed cerebral ischemia after SAH and to guide medical and endovascular therapy. The findings can lead to alterations in patient management.

Hypertonic Fluid Resuscitation from Subarachnoid Hemorrhage in Rats

OBJECTIVE

Increased intracranial pressure (ICP) and decreased cerebral blood flow leading to global cerebral ischemia are the primary causes of death after severe subarachnoid hemorrhage (SAH). Hypertonic saline has been demonstrated to exert neuroprotective properties after traumatic brain injury by osmotic mobilization of parenchymal water and improvement of microcirculation. We used a rat model to investigate the effects of hypertonic fluid resuscitation after SAH on ICP, cerebral blood flow, body weight, neurological recovery, and morphological damage.

METHODS

Sixty rats were subjected to SAH induced by an endovascular filament. ICP and local cerebral blood flow were recorded continuously. Animals were assigned to three groups: 1) NaCl 0.9%; 2) NaCl 7.5% (4 ml/kg); and 3) NaCl 7.5% plus 6% dextran 70 (4 ml/kg) given 30 minutes after SAH. Body weight and neurological deficits were assessed daily. Morphological damage was evaluated on Day 7.

RESULTS

SAH resulted in an immediate increase of ICP to approximately 60 mm Hg initially, and then to approximately 30 mm Hg for the next 90 minutes. Although NaCl 7.5% alone and in combination with dextran led to an immediate, significant, and lasting decrease of ICP to 15 to 20 mm Hg, only the combined therapy significantly increased body weight and improved neurological recovery. Furthermore, the group that received combined therapy exhibited significantly more surviving neurons in hippocampus, cortex, caudoputamen, and cerebellum. Mortality was reduced nonsignificantly, from approximately 65% in groups I and II to 35% in Group III.

CONCLUSION

Treatment with NaCl 7.5% plus 6% dextran 70 is significantly effective for reducing the initial harmful sequelae of SAH. The regimen resulted in lowered ICP, improved neurological recovery, and less morphological damage after SAH in the rat.

Monitoring of brain tissue oxygenation following severe subarachnoid hemorrhage

The purpose of this prospective observational study was to investigate the relation between the frequency of critical neuromonitoring parameters (brain tissue pO2, (PtiO2) < or = 10 mmHg, intracranial pressure (ICP) > 20 mmHg, cerebral perfusion pressure (CPP) < or = 70 mmHg) and outcome after severe aneurysmal subarachnoid hemorrhage (SAH). In a prospective study on 42 patients monitoring of ICP, CPP, and PtiO2 (in the area at risk for vasospasm) was performed. All patients were primarily classified as Hunt and Hess grade 4 or with secondary deterioration to this grade. Relative proportions of PtiO2 < or = 10 mmHg (n = 42), ICP > 20 mmHg (n = 25) and CPP < or = 70 mmHg (n = 23) were derived from multimodal neuromonitoring data sets for different time intervals, i.e. 1. the total monitoring time; 2. the total monitoring time without the last two monitoring days; 3. the second last monitoring day; and 4. the last monitoring day. Patients were divided into nonsurvivors (GOS = 1) and survivors (GOS = 3-5). For the total monitoring time, significant differences in the relative proportion of critical values were found for all neuromonitoring parameters (p < 0.05). The detailed analysis of consecutive time intervals revealed significantly increased proportions of critical values in nonsurvivors for all neuromonitoring parameters during the last day only. Additionally, ICP > 20 mmHg was significantly more frequent during the second last day (p < 0.01). For other time periods no differences were observed. We conclude, that critical neuromonitoring values are not early predictors of nonsurvival in patients suffering from severe SAH.

The relation between cerebral blood flow velocities as measured by TCD and the incidence of delayed ischemic deficits. A prospective study after subarachnoid hemorrhage

Patients (n = 127) with aneurysmal subarachnoid hemorrhage (SAH) were examined by transcranial Doppler ultrasonography (TCD) in a prospective study to follow the time course of the posthemorrhagic blood flow velocity in both the middle cerebral artery (MCA) and in the anterior cerebral artery (ACA). Results were analysed to reveal their relationship and predictive use with respect to the occurrence of delayed ischemic deficits. Mean flow velocities (MFV) higher than 120 cm sec(-1) in MCA and 90 cm sec(-1) in ACA were interpreted as indicative for significant vasospasm. In 20 of our 127 patients (16%) a delayed ischemic deficit (DID) was subsequently diagnosed clinically (DID+ group). Patients in the DID+ group can be characterized as those individuals who presented early during the observation period post-SAH with highest values of MFV, a faster increase and longer persistence of pathologically elevated MFV-values (exceeding 120 cm sec(-1) in MCA and 90 cm sec(-1) in ACA). They also show a greater difference in MFV-values if one compares the operated to the nonoperated side. Differences in MFV-values obtained in MCA or ACA were statistically significant (p < 0.05) for DID+ and DID- patients. The daily maximal increase of MFV was found between days 9 and 11 after SAH. In the DID+ group, the maximal MFV was 181 +/- 26 cm sec(-1) in MCA and 119 +/- 14 cm sec(-1) in ACA. In contrast to this, patients in the DID- group were found to present with MFV of 138 +/- 11 cm sec(-1) in MCA and 100 +/- 7 cm sec(-1) in ACA respectively. Delayed ischemic deficits appeared three times more often in DID+ patients than in patients with MFV < 120 cm sec(-1), if they showed a MFV > 120 cm sec(-1) in MCA. If pathological values were obtained in ACA, this ratio increases to about four times, if DID + patients presented with MFV > 90 cm sec(-1) versus patients with MFV < 90 cm sec(-1). Daily monitoring of vasospasm using TCD examination is thus helpful to identify patients at high risk for delayed ischemic deficits. This should allow us to implement further preventive treatment regimens.

Cerebral vasospasm and ischaemic infarction in clipped and coiled intracranial aneurysm patients

The influence of the treatment modalities (clipping/coiling) on the incidence of vasospasm and ischaemic infarction in aneurysm patients is still judged controversially. The purpose of this study was to analyse and compare retrospectively cerebral vasospasm and ischaemic infarction, as well as neurological deficits and outcome within a large population of clipped and coiled patients with ruptured and unruptured aneurysms. Within a 2-year period, a total of 144 interventions (53 clipping/91 coiling) entered the study. Daily bilateral transcranial Doppler sonographic monitoring was performed to observe vasospasm development. All cerebral computed tomography (cCT) and magnetic resonance imaging (MRI) scans were reviewed with respect to occurrence and localization of ischaemic infarctions. Focal neurological deficits were recorded and clinical outcome was evaluated using the Glasgow Outcome Scale. Statistical analysis included the use of multivariate logistic regression models to find determinants of vasospasm, ischaemic infarction and neurological deficits. Altogether, vasospasm was detected after 77 (53.5%) interventions, 61.8% in females (P < 0.01). Clipped patients significantly more often exhibited vasospasms (69.8 vs. 44.0%, P < 0.005) and were treated 1 week longer at the intensive care unit (P < 0.005). Seventy-seven patients (53.5%) developed ischaemic infarctions, 62.3% after clipping and 48.4% after coiling (P > 0.05). In the multivariate analysis, aneurysm-rupture was the strongest predictor for vasospasm and vasospasm was the strongest predictor for infarction. Neurological deficits at discharge (46.5%) were independent of treatment modality, the same applied for the mean Glasgow Outcome Scores. There was no significant difference in mortality between surgical and endovascular treatment (9.4 vs. 12.1%). Whilst the vasospasm incidence was significantly higher after surgical treatment, ischaemic infarctions were only slightly more frequent. The incidence of neurological deficits and clinical outcome was similar in both treatment groups.

Adverse cerebral events detected after subarachnoid hemorrhage using brain oxygen and microdialysis probes

OBJECTIVE

A prospective observational study was conducted to investigate whether episodes of ischemia are detected by continuous cerebral monitoring and whether such episodes are related to clinical outcome.

METHODS

Forty patients (35 after subarachnoid hemorrhage and 5 after complex aneurysm surgery) were monitored for a total of 174 days (mean, 4 d; range, 1-12 d). Brain tissue partial pressures of oxygen and carbon dioxide, pH, and temperature were measured continuously using Neurotrend sensors (Codman, Bracknell, England). Bedside analysis of extracellular chemistry was performed hourly using microdialysis. Glasgow Outcome Scale score was assessed at 3 to 6 months.

RESULTS

Patients with poor World Federation of Neurosurgical Societies grades (4 and 5) or an unfavorable outcome (severe disability or death) had, on average, higher lactate and lactate/pyruvate ratio but lower glucose/lactate ratio (P < or = 0.05). Brain tissue partial pressure of oxygen decreased to below 1.1 kPa in 78% of the patients for 18% (95% confidence interval, 12-24%) of time monitored. There were 197 episodes in which brain tissue partial pressures of oxygen decreased to below 1.1 kPa for at least 30 minutes. Unfavorable outcome was associated with more of these episodes (8.8 episodes; 95% confidence interval, 4.4-13.2 episodes) than favorable outcome (2.2 episodes; 95% confidence interval, 1.1-3.3 episodes), as well as an episode of glutamate levels of more than 10 micromol/L or lactate/pyruvate ratio more than 40 (P < 0.05, chi(2) test).

CONCLUSION

Intraparenchymal oximetry and microdialysis can detect but fail to predict the development of delayed cerebral ischemia. There were associations between episodes of low brain oxygen, abnormal microdialysis, and unfavorable outcome, but these associations were weak.

Effect of age on cerebral blood flow velocity and incidence of vasospasm after aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Current transcranial Doppler criteria for vasospasm after aneurysmal subarachnoid hemorrhage are not age specific. We analyzed the effect of age on cerebral blood flow velocity changes after subarachnoid hemorrhage and constructed an age-adjusted predictive model of cerebral blood flow velocity in subarachnoid hemorrhage patients.

METHODS

We identified patients with aneurysmal subarachnoid hemorrhage admitted between 1991 and 1999 with a prospective transcranial Doppler database. Eighty-one patients, with complete medical records and transcranial Doppler examinations of the vessels of interest, were included. Patients were subdivided into 2 groups by age: younger, <68 years of age (n=47) and older, >/=68 years of age (n=34). Maximum mean flow velocity and incidence of symptomatic vasospasm were reported. Linear and nonlinear regression analyses were performed.

RESULTS

Middle cerebral artery and internal carotid artery mean flow velocity were lower in older patients (median 76 versus 114 cm/s and 76 versus 126 cm/s, respectively; P<0.003). Incidence of symptomatic vasospasm was lower in older patients (44% versus 66%; P=0.05). Older patients developed symptomatic vasospasm at lower middle cerebral artery (median 57 versus 103 cm/s; P=0.04) and internal carotid artery (median 54 versus 81 cm/s, P=0.02) mean flow velocity. Relationship between middle cerebral artery and internal carotid artery mean flow velocity and age was quadratic (ANOVA, P<0.0001).

CONCLUSIONS

Older patients have a lower incidence of symptomatic vasospasm, and such vasospasm develops at lower cerebral blood flow velocity than younger patients. A quadratic relationship was found between age and cerebral blood flow velocity. This model could be used to create an age-adjusted nomogram that might improve diagnostic capabilities of transcranial Doppler.

Health-related quality of life after aneurysmal subarachnoid hemorrhage: impacts of bleeding severity, computerized tomography findings, surgery, vasospasm, and neurological grade

OBJECT

Based on the results of earlier studies it is agreed that the significance of aneurysm location and surgery for neuropsychological impairments after subarachnoid hemorrhage (SAH) is secondary to the effects of the bleeding itself. Therefore, the present study was performed to evaluate whether bleeding, acute clinical course, and surgery have persistent effects on health-related quality of life (QOL) after SAH.

METHODS

A series of 116 patients was examined for 4 to 5 years (mean 52.2 months) after aneurysmal SAH by means of a QOL questionnaire. Eighty-six patients (74.1%) had undergone surgery early (< or = 72 hours post-SAH). There were 77 women (66.4%) and 39 men (33.6%) in the study group, and the mean age of the patients was 50.3+/-13.3 years (range 30-69 years). Patients who had undergone surgery for a left-sided middle cerebral artery (MCA) aneurysm complained of significantly more impairments in social contact, communication, and cognition than those treated for a right-sided MCA aneurysm. No other effects of aneurysm location (including the anterior communicating artery) emerged. Multiple aneurysms, intraoperative aneurysm rupture, and partial resection of the gyrus rectus had no adverse effects on later daily life. Only temporary clipping was associated with increased complaints in some QOL areas. Disturbances of the circulation of cerebrospinal fluid and the presence of intraventricular hemorrhage led to more impairments in daily life. Specific effects of the anatomical pattern of the bleeding could be identified, but no adverse effects of vasospasm were found. Multivariate analyses revealed, in particular, that patient age and admission neurological status (Hunt and Hess grade) are substantial predictors of the psychosocial sequelae of SAH.

CONCLUSIONS

In contrast to the mild effects of aneurysm surgery, patient's age, initial neurological state on admission, and the bleeding pattern substantially influence late QOL after SAH.

Effect of hypervolemic therapy on cerebral blood flow after subarachnoid hemorrhage : a randomized controlled trial

BACKGROUND AND PURPOSE

Cerebral blood flow (CBF) is reduced after subarachnoid hemorrhage (SAH), and symptomatic vasospasm is a major cause of morbidity and mortality. Volume expansion has been reported to increase CBF after SAH, but CBF values in hypervolemic (HV) and normovolemic (NV) subjects have never been directly compared.

METHODS

On the day after aneurysm clipping, we randomly assigned 82 patients to receive HV or NV fluid management until SAH day 14. In addition to 80 mL/h of isotonic crystalloid, 250 mL of 5% albumin solution was given every 2 hours to maintain normal (NV group, n=41) or elevated (HV group, n=41) cardiac filling pressures. CBF ((133)xenon clearance) was measured before randomization and approximately every 3 days thereafter (mean, 4.5 studies per patient).

RESULTS

HV patients received significantly more fluid and had higher pulmonary artery diastolic and central venous pressures than NV patients, but there was no effect on net fluid balance or on blood volume measured on the third postoperative day. There was no difference in mean global CBF during the treatment period between HV and NV patients (P=0.55, random-effects model). Symptomatic vasospasm occurred in 20% of patients in each group and was associated with reduced minimum regional CBF values (P=0.04). However, there was also no difference in minimum regional CBF between the 2 treatment groups.

CONCLUSIONS

HV therapy resulted in increased cardiac filling pressures and fluid intake but did not increase CBF or blood volume compared with NV therapy. Although careful fluid management to avoid hypovolemia may reduce the risk of delayed cerebral ischemia after SAH, prophylactic HV therapy is unlikely to confer an additional benefit.

CT assessment of cerebral perfusion: experimental validation and initial clinical experience

PURPOSE

To validate a dynamic single-section computed tomographic (CT) method to measure cerebral blood volume (CBV) and cerebral blood flow (CBF) by using a noncarotid artery as the input and to demonstrate the feasibility of this method in a pilot series of patients.

MATERIALS AND METHODS

Twelve dynamic contrast material-enhanced CT studies were performed in beagles. CBV, CBF, and mean transit time (MTT) values were calculated by using an internal carotid artery (ICA) and a noncarotid artery as the input artery to the brain. Patient studies with use of the radial artery as the input were performed (a) repetitively in two patients after subarachnoid hemorrhage, (b) in a patient with a symptomatic ICA occlusion before and after the intravenous injection of 1 g of acetazolamide, and (c) in a patient with a malignant brain tumor.

RESULTS

Linear regression analyses revealed highly significant correlations (P < .001) between CBV (r, 0.98; slope, 0.96), CBF (r, 0.89; slope, 0.87), and MTT (r, 0.80; slope, 0.76) values calculated with the ICA and the noncarotid inputs. The CT-derived patient data correlated well with ancillary clinical and neuroradiologic findings.

CONCLUSION

Dynamic single-section CT scanning to measure CBV and CBF on the basis of a noncarotid input is a highly accessible and cost-effective blood flow measurement technique.

Intracranial aneurysms and subarachnoid hemorrhage management of the poor grade patient

Between 20 and 30% of patients who suffer cerebral aneurysm rupture are in poor clinical grade when first evaluated. Management of these patients is controversial and challenging but can be successful with an aggressive proactive approach that begins with in the field resuscitation and continues through rehabilitation. In this article we review the epidemiology, pathology and pathophysiology, clinical features, evaluation, surgical and endovascular management, critical care, cost, and outcome prediction of patients in poor clinical grade after subarachnoid hemorrhage.

The role of transcranial Doppler in the management of patients with subarachnoid haemorrhage--a review

Introduced 15 years ago, transcranial Doppler (TCD) recordings of blood-velocity in patients with recent subarachnoid haemorrhage (SAH) have two objectives: to detect elevated blood velocities suggesting cerebral vasospasm (VSP) and to identify patients at risk for delayed cerebral ischemic deficits (DID). The pathophysiological cascade causing DID is complex. Discrepancies between blood velocities and DID (presuming that there actually is an "ischemic threshold" for blood velocity in absolute terms, which seems most unlikely) have been demonstrated, particularly in patients with elevated intracranial pressure (ICP) levels. Furthermore, the vessel showing the highest blood velocity is not always the one perfusing the area where ischemic symptoms arise, nor does the site of the greatest subarachnoid blood clot always relate to the ischemic brain region. Moreover, it is probable that the complex haemodynamic changes following SAH and the subsequent development of VSP may be underestimated if only considering the crude intracranial artery blood velocities. Cerebral blood flow measurements combined with TCD to assess both flow and velocity have emphasised this point. Despite these findings and ignoring the basic principles of cerebral haemodynamics, cerebral vasospasm is still being assessed from the intracranial velocity measurement alone. The addition of at least a careful measurement from the extracranial internal carotid artery--using the same TCD equipment and taking only a few short minutes to perform--allows a much more accurate assessment of the degree and the effects of vasospasm. This probably explains why the clinical value of TCD is still debated. There is still uncertainty as to the best method to prevent and to treat VSP, and the overall outcome after SAH depends on so many factors besides VSP. Conclusive evidence may therefore be hard to obtain, and it appears sound to conclude that even with advanced investigation technology available, proper selection, pre- peri- and postoperative care and timing of surgery remain cornerstones in the management of these patients,--equal in importance to their treatment in the operating room or in the interventional angiography suite.

Effect of clot removal and surgical manipulation on regional cerebral blood flow and delayed vasospasm in early aneurysm surgery for subarachnoid hemorrhage

BACKGROUND

Effect of clot removal and surgical manipulation on cerebral blood flow (CBF) and delayed vasospasm was studied in early aneurysm surgery for subarachnoid hemorrhage (SAH).

METHODS

Thirty-two patients in this study fulfilled the following criteria: ruptured anterior communicating aneurysms, computed tomography (CT) within 2 days and unilateral pterional approach within 3 days after the ictus, bilaterally symmetrical clots without intracerebral hematoma, no postoperative complication, and CBF studies with single photon emission computed tomography (SPECT) with 123I-IMP.

RESULTS

Postoperative regional hypoperfusion due to brain retraction was frequently recognized on 123I-IMP-SPECT without infarction. The regional CBF (rCBF) showed a continuous fall during the first 4 weeks after the ictus, followed by improvement. The rCBF in the vicinity of the surgical route was significantly lower, especially in the acute stage (Day 3-7). A significant association between decrease of cisternal blood after surgery and the degree of local vasospasm and local CBF values during spasm stage was observed in the interhemispheric cisterns, A2 and medial frontal cortex, but not in the sylvian fissure or insular cisterns, M1 or M2, and frontal watershed and temporal cortex.

CONCLUSIONS

The present study provides evidence for the effectiveness of direct clot removal by early surgery for SAH on local vasospasm and CBF reduction. However, a potential improvement in local CBF with clot removal could be masked by brain retraction, which was demonstrated to affect rCBF adversely. Therefore, it is critical to perform brain retraction as gently as possible.

Functional changes in human pial arteries (300 to 900 micrometer ID) within 48 hours of aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Animal studies of cerebral arteries 2 to 3 days after experimental subarachnoid hemorrhage (SAH) provide evidence of arterial change such as hyperresponsiveness to contractile agonists. There is evidence that small arteries, as well as those large enough to be seen on angiography, may be involved. To directly test these possibilities, the contractile and dilator responses of pial artery segments taken from patients up to 48 hours after SAH were compared with those from patients having elective surgery for an aneurysm (Clip) and with those from normal brain vessels overlying tumors (controls).

METHODS

Segments were mounted on a resistance artery myograph for measurements of wall force changes.

RESULTS

There were no differences in maximum contractility (Emax) of the 3 groups of segments. The responses of the SAH segments to K+ (30 mmol/L) were 60.7+/-4.6% of Emax (n [number of vessels]=18), which was significantly greater than those of controls (29.9+/-5% Emax) (n=20). Clip responses were the same as control. Contractions of SAH segments to norepinephrine (1 micromol/L) were 54.3+/-7.9% Emax (n=12), and these were significantly greater than those of controls (15.1+/-6.2% Emax) (n=25). All SAH segments showed spontaneous contractile activity of varying patterns. Spontaneous activity did not occur in the Clip group and occurred in only 50% of control segments. Dilation to acetylcholine was numerically less in SAH and Clip segments than in controls, but differences were not statistically significant. The change in agonist responsiveness could result from exposure to agents that damage the blood vessel wall, resulting in partial depolarization of endothelial and smooth muscle cells.

CONCLUSIONS

Small human pial arteries are hyperresponsive to contractile agents and show spontaneous contractile activity within 48 hours of SAH. Such effects could result in narrowed resistance arteries and reduction in cerebral blood flow. These effects emphasize the wisdom of early therapeutic intervention.

Oxidative stress in the human brain after subarachnoid hemorrhage

OBJECT

The aim of this study was to verify the patterns of antioxidant enzymatic activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in the human brain after subarachnoid hemorrhage (SAH) to verify whether an "oxidative stress situation" characterizes the brain response to subarachnoid bleeding.

METHODS

Forty samples of gyrus rectus or temporal operculum that were obtained during a surgical approach to anterior circulation aneurysms were used for this study. The activity of total SOD, GSH-Px, and the SOD/GSH/Px ratio (which expresses the balance between the production of hydrogen peroxides by dismutation of superoxide radicals and the scavenging potential) were calculated in each case. Twelve samples were obtained from patients who underwent surgery for unruptured aneurysms (control group); 13 samples were obtained during surgical procedures performed within 72 hours of SAH; and 15 samples were obtained during delayed surgical procedures (> 10 days post-SAH). Ten patients presented with clinical deterioration caused by arterial vasospasm. In both SAH groups, the mean total SOD activity was significantly higher than in the control group (p=0.029). The mean activity of GSH-Px did not differ significantly between the SAH and control groups (p=0.731). There was a significant increase in the SOD/GSH-Px ratio in both SAH groups, as compared with controls (p < 0.05). There was a significant correlation between the enzymatic activity and the clinical severity of the hemorrhage, with findings of lower values of SOD and, mainly, of the SOD/GSH-Px ratio in the poor-grade patients. The SOD/GSH-Px ratio was 2.14+/-0.44 in patients who presented with clinical vasospasm and 1.24+/-0.2 in cases without vasospasm.

CONCLUSIONS

The results of this study show an imbalance of the antioxidant enzymatic activities in the human brain after SAH. which is linked to the severity of the initial bleeding and possibly modified by the development of arterial vasospasm.

Jugular saturation (SjvO2) monitoring in subarachnoid hemorrhage (SAH)

Jugular saturation (SjvO2) monitoring was performed in 26 SAH patients to evaluate the incidence of normal (0.56-0.74) and pathological SjvO2 values in this population and to describe its time course in the first 12 days. We also attempt to quantify the influence of systemic and cerebral hemodynamics on SjvO2 and to assess the relationship between cerebral injury volume measured on CT scan and SjvO2. Mean SjvO2 was 0.66 +/- 0.07 (354 samples, median 0.67, range 0.43-0.89). 73% of the observations (259/354) were in the normal range. On serial measurements, we identified only 37/354 (10%) desaturation episodes (D.E.). ICP was significantly higher during low SjvO2 observation (p = 0.008). No statistical differences were noted regarding the influence of MAP, CPP, PaCO2, PaO2 on SjvO2 but during D.E., lower PaCO2 and CPP were more frequently observed. CT scan lesions > 25 ml were associated initially with lower SjvO2 values and with higher values at second CT.