Safety of intrathecal sodium nitroprusside for the treatment and prevention of refractory cerebral vasospasm and ischemia in humans

Assessment of the Effects of Sodium Nitroprusside Administered Via Intracranial Subdural Catheters on the Cerebral Blood Flow and Lactate Using Dynamic Susceptibility Contrast Magnetic Resonance Imaging and Proton Magnetic Resonance Spectroscopy in a Pig Cardiac Arrest Model

Background Cerebral blood flow (CBF) is impaired in the early phase after return of spontaneous circulation. Sodium nitroprusside (SNP) administration via intracranial subdural catheters improves cerebral cortical microcirculation. We determined whether the SNP treatment improves CBF in the subcortical tissue and evaluated the effects of this treatment on cerebral lactate. Methods and Results Sixty minutes after return of spontaneous circulation following 14 minutes of untreated cardiac arrest, 14 minipigs randomly received 4 mg SNP or saline via intracranial subdural catheters. CBF was measured in regions of interest within the cerebrum and thalamus using dynamic susceptibility contrast-magnetic resonance imaging. After return of spontaneous circulation, CBF was expressed as a percentage of the baseline value. In the saline group, the %CBF in the regions of interest within the cerebrum remained at approximately 50% until 3.5 hours after return of spontaneous circulation, whereas %CBF in the thalamic regions of interest recovered to approximately 73% at this time point. The percentages of the baseline values in the cortical gray matter and subcortical white matter were higher in the SNP group (group effect P=0.026 and 0.025, respectively) but not in the thalamus. The cerebral lactate/creatine ratio measured using magnetic resonance spectroscopy increased over time in the saline group but not in the SNP group (group-time interaction P=0.035). The thalamic lactate/creatine ratio was similar in the 2 groups. Conclusions SNP administered via intracranial subdural catheters improved CBF not only in the cortical gray matter but also in the subcortical white matter. The CBF improvement by SNP was accompanied by a decrease in cerebral lactate.

Health Care Expenditures Associated with Delayed Cerebral Ischemia Following Subarachnoid Hemorrhage: A Propensity-Adjusted Analysis

OBJECTIVE

The additional hospital costs associated with delayed cerebral ischemia (DCI) have not been well investigated in prior literature. In this study, the total hospital cost of DCI in aneurysmal subarachnoid hemmorhage (aSAH) patients treated at a single quaternary center was analyzed.

METHODS

All patients in the Post-Barrow Ruptured Aneurysm Trial treated for an aSAH between January 1, 2014, and July 31, 2019, were retrospectively analyzed. DCI was defined as cerebral infarction identified on computed tomography, magnetic resonance imaging, or autopsy after exclusion of procedure-related infarctions. The primary outcome was the difference in total cost (including hospital, discharge facility, and all follow-up) using a propensity-adjusted analysis. Propensity score covariate-adjusted linear regression analysis included age, sex, open versus endovascular treatment, Hunt and Hess score, and Charlson Comorbidity Index score.

RESULTS

Of the 391 patients included, 144 (37%) had DCI. Patients with DCI had a significantly greater cost compared to patients without DCI (mean standard deviation $112,081 [$54,022] vs. $86,159 [$38,817]; P < 0.001) and a significantly greater length of stay (21 days [11] vs. 18 days [8], P = 0.003, respectively). In propensity-adjusted linear regression analysis, both DCI (odds ratio, $13,871; 95% confidence interval, $7558-$20,185; P < 0.001) and length of stay (odds ratio, $3815 per day; 95% confidence interval, $3480-$4149 per day; P < 0.001) were found to significantly increase the cost.

CONCLUSIONS

The significantly higher costs associated with DCI further support the evidence that adverse effects associated with DCI in aSAH pose a significant burden to the health care system.

Effects of Sodium Nitroprusside Administered Via a Subdural Intracranial Catheter on the Microcirculation, Oxygenation, and Electrocortical Activity of the Cerebral Cortex in a Pig Cardiac Arrest Model

Background

Postischemic cerebral hypoperfusion has been indicated as an important contributing factor to secondary cerebral injury after cardiac arrest. We evaluated the effects of sodium nitroprusside administered via a subdural intracranial catheter on the microcirculation, oxygenation, and electrocortical activity of the cerebral cortex in the early postresuscitation period using a pig model of cardiac arrest.

Methods and Results

Twenty‐nine pigs were resuscitated with closed cardiopulmonary resuscitation after 14 minutes of untreated ventricular fibrillation. Thirty minutes after restoration of spontaneous circulation, 24 pigs randomly received either 4 mg of sodium nitroprusside (IT‐SNP group) or saline placebo (IT‐saline group) via subdural intracranial catheters and were observed for 5 hours. The same dose of sodium nitroprusside was administered intravenously in another 5 pigs. Compared with the IT‐saline group, the IT‐SNP group had larger areas under the curve for tissue oxygen tension and percent changes of arteriole diameter and number of perfused microvessels from baseline (all P<0.05) monitored on the cerebral cortex during the 5‐hour period, without severe hemodynamic instability. This group also showed faster recovery of electrocortical activity measured using amplitude‐integrated electroencephalography. Repeated‐measures analysis of variance revealed significant group–time interactions for these parameters. Intravenously administered sodium nitroprusside caused profound hypotension but did not appear to increase the cerebral parameters.

Conclusions

Sodium nitroprusside administered via a subdural intracranial catheter increased post–restoration of spontaneous circulation cerebral cortical microcirculation and oxygenation and hastened electrocortical activity recovery in a pig model of cardiac arrest. Further studies are required to determine its impact on the long‐term neurologic outcomes.

Neuroprotective effect of dapsone in patients with aneurysmal subarachnoid hemorrhage: a prospective, randomized, double-blind, placebo-controlled clinical trial

OBJECTIVE

In this study, the authors sought to define the differences in the incidence of delayed cerebral ischemia (DCI) between patients treated with dapsone and those treated with placebo. Secondary objectives were to define the clinical outcome at discharge and 3 months and the incidence of brain infarction.

METHODS

A prospective, randomized, double-blind, placebo-controlled study was performed and included patients with aneurysmal subarachnoid hemorrhage (SAH) within 5 days from ictus who were candidates for aneurysm occlusion, and who had a Fisher grade of 3 or 4. Patients with sulfa or sulfone drug allergies, hemoglobin < 11 g/dl, known G6PD deficiency, and those refusing informed consent were excluded. A minimal relevant effect decrease of 35% in the incidence of DCI was established. Patients were randomly assigned to receive a regimen of dapsone 2.5 ml (100 mg) daily or a placebo (aluminum hydroxide suspension, 2.5 ml daily). Both groups received validated treatment for aneurysmal SAH. The appearance of DCI on CT was assessed in every patient at discharge and 3 months later. We used the chi-square test to compare the DCI incidence between both groups, and the Student t-test or nonparametric tests to compare quantitative variables.

RESULTS

Overall, 48 patients (70.8% women and 29.2% men) were included. The mean age was 50 years (SD 14.28 years, range 18-72 years). Prerandomization and postrandomization characteristics were balanced, except for the necessity of intra-arterial nimodipine administration in patients treated with placebo (15.4% vs 45.5%, p = 0.029. The incidence of DCI, the primary endpoint, for the whole cohort was 43.8% and was significantly lower in the dapsone group (26.9% vs 63.6%, p = 0.011). In addition, the irreversible DCI incidence was lower in the dapsone group (11.5% vs 54.5%, p = 0.12). A favorable modified Rankin Scale score was more frequent in the dapsone group at discharge and at 3 months (76.9% vs 36.4%, p = 0.005 and 80% vs 38.9%, p = 0.019, respectively). Also, the brain infarction incidence was lower in the dapsone group (19.2% vs 63.6%, p = 0.001). There was no difference between groups regarding adverse events.

CONCLUSIONS

Dapsone seems to play a role as a prophylactic agent in patients at high risk of developing DCI after aneurysmal SAH. A multicenter investigation is necessary to increase the study population and confirm the consistency of the results observed in this study.

Nitric Oxide-Dependent Pathways as Critical Factors in the Consequences and Recovery after Brain Ischemic Hypoxia

Brain ischemia is one of the leading causes of disability and mortality worldwide. Nitric oxide (NO^•), a molecule that is involved in the regulation of proper blood flow, vasodilation, neuronal and glial activity constitutes the crucial factor that contributes to the development of pathological changes after stroke. One of the early consequences of a sudden interruption in the cerebral blood flow is the massive production of reactive oxygen and nitrogen species (ROS/RNS) in neurons due to NO^• synthase uncoupling, which leads to neurotoxicity. Progression of apoptotic or necrotic neuronal damage activates reactive astrocytes and attracts microglia or lymphocytes to migrate to place of inflammation. Those inflammatory cells start to produce large amounts of inflammatory proteins, including pathological, inducible form of NOS (iNOS), which generates nitrosative stress that further contributes to brain tissue damage, forming vicious circle of detrimental processes in the late stage of ischemia. S-nitrosylation, hypoxia-inducible factor 1α (HIF-1α) and HIF-1α-dependent genes activated in reactive astrocytes play essential roles in this process. The review summarizes the roles of NO^•-dependent pathways in the early and late aftermath of stroke and treatments based on the stimulation or inhibition of particular NO^• synthases and the stabilization of HIF-1α activity.

A novel rescue therapy for cerebral vasospasm: Cisternal Nimodipine application via stereotactic catheter ventriculocisternostomy

Delayed Cerebral Infarction (DCI) due to Cerebral Vasospasm (CVS) is an important contributor to poor outcome after aneurysmal subarachnoid haemorrhage (aSAH). Despite established risk factors CVS and DCI are unpredictable at the individual patient level. Efficient treatments are lacking. We report a novel rescue therapy for DCI: Access to the basal cisterns by stereotactic catheter ventriculocisternostomy (STX-VCS) and direct cisternal application of the spasmolytic agent Nimodipine. On the basis of individual treatment decisions three aSAH patients who developed CVS underwent STX-VCS. Continuous lavage with Nimodipine was performed. CVS was assessed by daily transcranial doppler ultrasonography. Neurological outcome at 3 months was assessed by modified Rankin scale. STX-VCS was performed without complications in all patients. CVS rapidly resolved upon cisternal application of Nimodipine. CVS recurred in two patients upon interruption of Nimodpine application and resolved upon restart of Nimodipine. DCI did not occur in all three cases. STX-VCS and cisternal Nimodipine application is a novel rescue therapy for CVS treatment and DCI-prevention in patients with aSAH.

A pilot study on assessing the role of intra-operative Flow 800 vascular map model in predicting onset of vasospasm following micro vascular clipping of ruptured intracranial aneurysms

Objective To ascertain the predictive value of intra-operative FLOW 800 vascular map model in predicting onset of post-operative clinical vasospasm and delayed cerebral ischemia among patients undergoing micro-vascular clipping of ruptured intracranial aneurysms.  Material and methods A total of 40 patients were enrolled in the study and their variables such as age, World Federation of Neurological Surgeons (WFNS) grade at presentation, Computerized Tomography (CT) Fisher grading, location of the aneurysms, and Indocyanine Green (ICG) flow status were compared and statistically analyzed along with differences in Absorption Intensities (AI) and difference in time lag values obtained from the FLOW 800 vascular map studies for predicting onset of vasospasm.  Results The Receiver Operating curve (ROC) of the model for predicting post-operative vasospasm was highest (.892) for difference in the AI followed by CT Fisher grading (.778), difference in time lag (.700) and WFNS grading (.699).Analysis of variance for different variables studied in our model for predicting vasospasm was significant for all except for age (.991) and the ICG flow through the parent vessel (.079).Multivariate analysis done for predicting the vasospasm was significant for all variables except for age (.869) and ICG main flow (.196) Conclusion Our study confirmed the role of FLOW 800 study model in predicting clinical vasospasm. Inclusion of this entity would therefore help in taking timely and correct therapeutics measures to ensure better patient outcomes.

Early changes of brain perfusion after subarachnoid hemorrhage - the effect of sodium nitroprusside

Causes of early hypoperfusion after subarachnoid hemorrhage (SAH) include intracranial hypertension as well as vasoconstriction. The aim of the study was to assess the effect of intracerebroventricular (ICV) administration of sodium nitroprusside (SNP) on early hypoperfusion after SAH. Male Wistar rats (220-240 g) were used, SAH group received 250 microl of fresh autologous arterial blood into the prechiasmatic cistern; sham-operated animals received 250 microl of isotonic solution. Therapeutic intervention: ICV administration of 10 microg SNP; 5 microl 5 % glucose (SNP vehicle) and untreated control. Brain perfusion and invasive blood pressure were monitored for 30 min during and after induction of SAH. Despite SNP caused increase of perfusion in sham-operated animals, no response was observed in half of SAH animals. The other half developed hypotension accompanied by brain hypoperfusion. There was no difference between brain perfusion in SNP-treated, glucose-treated and untreated SAH animals during the monitored period. We did not observe expected beneficial effect of ICV administration of SNP after SAH. Moreover, half of the SNP-treated animals developed serious hypotension which led to brain hypoperfusion. This is the important finding showing that this is not the option for early management in patient after SAH.

Management of delayed cerebral ischemia after subarachnoid hemorrhage

For patients who survive the initial bleeding event of a ruptured brain aneurysm, delayed cerebral ischemia (DCI) is one of the most important causes of mortality and poor neurological outcome. New insights in the last decade have led to an important paradigm shift in the understanding of DCI pathogenesis. Large-vessel cerebral vasospasm has been challenged as the sole causal mechanism; new hypotheses now focus on the early brain injury, microcirculatory dysfunction, impaired autoregulation, and spreading depolarization. Prevention of DCI primarily relies on nimodipine administration and optimization of blood volume and cardiac performance. Neurological monitoring is essential for early DCI detection and intervention. Serial clinical examination combined with intermittent transcranial Doppler ultrasonography and CT angiography (with or without perfusion) is the most commonly used monitoring paradigm, and usually suffices in good grade patients. By contrast, poor grade patients (WFNS grades 4 and 5) require more advanced monitoring because stupor and coma reduce sensitivity to the effects of ischemia. Greater reliance on CT perfusion imaging, continuous electroencephalography, and invasive brain multimodality monitoring are potential strategies to improve situational awareness as it relates to detecting DCI. Pharmacologically-induced hypertension combined with volume is the established first-line therapy for DCI; a good clinical response with reversal of the presenting deficit occurs in 70 % of patients. Medically refractory DCI, defined as failure to respond adequately to these measures, should trigger step-wise escalation of rescue therapy. Level 1 rescue therapy consists of cardiac output optimization, hemoglobin optimization, and endovascular intervention, including angioplasty and intra-arterial vasodilator infusion. In highly refractory cases, level 2 rescue therapies are also considered, none of which have been validated. This review provides an overview of current state-of-the-art care for DCI management.

A Case of Hyperacute Onset of Vasospasm After Aneurysmal Subarachnoid Hemorrhage and Refractory Vasospasm Treated with Intravenous and Intraventricular Nitric Oxide: A Mini Review

BACKGROUND

A case of hyperacute vasospasm, indicating a poor prognosis after aneurysmal subarachnoid hemorrhage (SAH), is reported, and a review is presented of the literature addressing use of nitric oxide (NO) donors in cases of refractory vasospasm and recurrent delayed cortical ischemias (DCI).

CASE DESCRIPTION

A 65-year-old woman was admitted within 1 hour after aneurysmal SAH (Hunt and Hess grade III, Fisher modified by Frontera grade IV). A hyperacute vasospasm had been confirmed arteriographically, the right middle cerebral artery (MCA) aneurysm was immediately coiled and a standard antivasospastic therapy was started. Within 48 hours, the patient developed cerebral vasospasm with DCI. Because the standard therapy failed to control clinical symptoms and to address severe vasospasm, an individualized rescue treatment with NO donors was initiated. A continuous intravenous molsidomine infusion was started and clinical stabilization was achieved for a week (Hunt and Hess grade I; World Federation of Neurological Surgeons grade I; Glasgow Coma Scale score, 15) after which vasospasm and DCI recurred. During a subsequent DCI, we escalated NO donor therapy by adding intraventricular boluses of sodium nitroprusside (SNP). Over the course of the following 22 days, 7 transient DCIs (Glasgow Coma Scale score, 8) were treated with boluses of SNP during continued molsidomine therapy and each time vasospasm and DCI were completely reversed. Despite initial poor prognosis, the clinical outcome was excellent; at 3, 6, and 12 months follow-up the patient's modified National Institutes of Health-Stroke Scale and modified Rankin Scale scores were 0, with no cognitive deficits.

CONCLUSIONS

The review of the literature suggested that combined intravenous molsidomine with intraventricular SNP treatment reversed refractory, recurrent vasospasm and DCIs probably by addressing the hemoglobin NO sink effect, NO depletion, and decreased NO availability after aneurysmal SAH.

Sodium nitroprusside: low price and safe drug to control BP during thrombolysis in AIS

This study analyzes the use of sodium nitroprusside (SN) as an option to reduce blood pressure (BP) below 180/105 mmHg during the management of acute ischemic stroke (AIS) in patients submitted to intravenous thrombolysis.Method The sample was composed by 60 patients who had AIS and were submitted to intravenous rtPA, split in two groups: half in the control group (CG) with BP < 180/105 mmHg and half in SN group with BP > 180/105 mmHg. Outcome variables were any hemorrhagic transformation (HT); the presence of symptomatic HT, National Institute of Health Stroke Scale (NIHSS) after 24 hours of treatment; the independence on discharge and death until three months after stroke onset.Results There were no statistical differences between both groups to any of the outcome variables analyzed.Conclusion The SN might be safe for BP control during thrombolysis to AIS.

The effect of irrigation of intracisternal papaverine on cerebral blood flow in subarachnoid hemorrhage

BACKGROUND

Despite different treatments, cerebral vasospasm is still the most important cause of death in patients after subarachnoid hemorrhage. This study was conducted to explore the effect of intracisternal washing with papaverine on cerebral blood flow.

MATERIALS AND METHODS

This study was performed on 40 patients and totally 120 arteries in 2010. Then, variations in cerebral blood flow before and after washing with papaverine were measured and analyzed.

RESULTS

Twenty (20) patients with aneurysm of the anterior communicating artery (ACOM) and 20 patients with aneurysm of the middle cerebral artery (MCA) were assessed. Mean blood flow before aneurysm and before washing in ACOM and MCA was 70.68 ± 14.8 cm/s and 65.66 ± 9.3 cm/s, respectively, which reached 23.25 ± 5.17 cm/s and 34.1 ± 4.7 cm/s, respectively after washing (P value = 0.016 and 0.024). Mean blood flow after aneurysm and before washing in ACOM and MCA was 95.12 ± 13.9 cm/s and 67.44 ± 15.16 cm/s, respectively, which reached 35.69 ± 6.2 cm/s and 38.01 ± 8.28 cm/s, respectively after washing (P value = 0.001 and 0.01).

CONCLUSION

Washing with papaverine significantly reduces cerebral blood flow and relieves vasospasm.

Nitric oxide in cerebral vasospasm: theories, measurement, and treatment

In recent decades, a large body of research has focused on the role of nitric oxide (NO) in the development of cerebral vasospasm (CV) following subarachnoid hemorrhage (SAH). Literature searches were therefore conducted regarding the role of NO in cerebral vasospasm, specifically focusing on NO donors, reactive nitrogen species, and peroxynitrite in manifestation of vasospasm. Based off the assessment of available evidence, two competing theories are reviewed regarding the role of NO in vasospasm. One school of thought describes a deficiency in NO due to scavenging by hemoglobin in the cisternal space, leading to an NO signaling deficit and vasospastic collapse. A second hypothesis focuses on the dysfunction of nitric oxide synthase, an enzyme that synthesizes NO, and subsequent generation of reactive nitrogen species. Both theories have strong experimental evidence behind them and hold promise for translation into clinical practice. Furthermore, NO donors show definitive promise for preventing vasospasm at the angiographic and clinical level. However, NO augmentation may also cause systemic hypotension and worsen vasospasm due to oxidative distress. Recent evidence indicates that targeting NOS dysfunction, for example, through erythropoietin or statin administration, also shows promise at preventing vasospasm and neurotoxicity. Ultimately, the role of NO in neurovascular disease is complex. Neither of these theories is mutually exclusive, and both should be considered for future research directions and treatment strategies.

Medical Management of Cerebral Vasospasm following Aneurysmal Subarachnoid Hemorrhage: A Review of Current and Emerging Therapeutic Interventions

Cerebral vasospasm is a major source of morbidity and mortality in patients with aneurysmal subarachnoid hemorrhage (aSAH). Evidence suggests a multifactorial etiology and this concept remains supported by the assortment of therapeutic modalities under investigation. The authors provide an updated review of the literature for previous and recent clinical trials evaluating medical treatments in patients with cerebral vasospasm secondary to aSAH. Currently, the strongest evidence supports use of prophylactic oral nimodipine and initiation of triple-H therapy for patients in cerebral vasospasm. Other agents presented in this report include magnesium, statins, endothelin receptor antagonists, nitric oxide promoters, free radical scavengers, thromboxane inhibitors, thrombolysis, anti-inflammatory agents and neuroprotectants. Although promising data is beginning to emerge for several treatments, few prospective randomized clinical trials are presently available. Additionally, future investigational efforts will need to resolve discrepant definitions and outcome measures for cerebral vasospasm in order to permit adequate study comparisons. Until then, definitive recommendations cannot be made regarding the safety and efficacy for each of these therapeutic strategies and medical management practices will continue to be implemented in a wide-ranging manner.

Attenuation of cerebral vasospasm following experimental subarachnoid hemorrhage by the bronchodilator KMUP-3

Delayed cerebral vasospasm is a main cause of morbidity and mortality as well as poor outcome in patients following aneurysmal subarachnoid hemorrhage (SAH). In this study, the effect of the bronchodilator KMUP-3 (7-[2-[4-(4-nitrobenzene)piperazinyl]ethyl]-1,3-dimethylxanthine) on basilar artery narrowing, neurological outcome, and expression of rhoA/rho kinase II (ROCKII), rhoA, and protein kinase C (PKC) γ proteins were evaluated in a rat model of SAH. SAH was induced by double injection of autologous blood into the cistern magna on days 0 and 3. KMUP-3 was administered (0.3 mg/kg/day) by osmotic minipumps implanted subcutaneously (beginning day -3 in pretreatment group and at 1 h after the initiation of the first autologous blood injection in the treatment group). Neurological outcome was assessed by ambulation and placing/stepping reflex responses at 48 h after the second injection of autologous blood. Tissue morphology and protein expression were conducted on day 7 post-day 0 injection. Both KMUP-3 treatment regimens significantly improved neurological outcome and completely attenuated basilar artery narrowing as well as reduced the enhancement of ROCKII, rhoA, and PKCγ protein expression in rats subjected to SAH, compared with normal and untreated SAH rats. These results suggest that KMUP-3 may be a novel agent for the treatment of cerebral vasospasm following SAH.

Current therapeutic strategies to mitigate the eNOS dysfunction in ischaemic stroke

Impairment of endothelial nitric oxide synthase (eNOS) activity is implicated in the pathogenesis of endothelial dysfunction in many diseases including ischaemic stroke. The modulation of eNOS during and/or following ischaemic injury often represents a futile compensatory mechanism due to a significant decrease in nitric oxide (NO) bioavailability coupled with dramatic increases in the levels of reactive oxygen species that further neutralise NO. However, applications of a number of therapeutic agents alone or in combination have been shown to augment eNOS activity under a variety of pathological conditions by potentiating the expression and/or activity of Akt/eNOS/NO pathway components. The list of these therapeutic agents include NO donors, statins, angiotensin-converting enzyme inhibitors, calcium channel blockers, phosphodiesterase-3 inhibitors, aspirin, dipyridamole and ellagic acid. While most of these compounds exhibit anti-platelet properties and are able to up-regulate eNOS expression in endothelial cells and platelets, others suppress eNOS uncoupling and tetrahydrobiopterin (an eNOS stabiliser) oxidation. As the number of therapeutic molecules that modulate the expression and activity of eNOS increases, further detailed research is required to reveal their mode of action in preventing and/or reversing the endothelial dysfunction.

Protein therapy using heme-oxygenase-1 fused to a polyarginine transduction domain attenuates cerebral vasospasm after experimental subarachnoid hemorrhage

A sequence of 11 consecutive arginine residues (11R) is one of the best protein transduction domains for introducing proteins into cell membranes. Heme-oxygenase-1 (HO-1) is involved in heme catabolism and reduces the contractile effect of hemoglobin after subarachnoid hemorrhage (SAH). Therefore, we constructed 11R-fused HO-1 protein to achieve successful transduction of the protein into the cerebral arteries and examined the therapeutic effect of the 11R-HO-1 protein for cerebral vasospasm (CV) after SAH. We injected the 11R-HO-1 protein into the cisterna magna of male rats and, several hours after the injection, performed immunofluorescence staining and western blotting analysis of the rat basilar arteries (BAs) to determine transduction efficacy. We also assessed intraarterial HO-1 activity as cGMP (cyclic guanosine 3', 5'-cyclic monophosphate) accumulation in SAH and determined whether protein transduction of 11R-HO-1 quantified the therapeutic effect in a rat double-hemorrhage model of SAH. The BAs expressed significantly more HO-1 in the group injected with 11R-HO-1 (3.56±0.54 (11R-HO-1) versus control (saline)), and transduction of 11R-HO-1 resulted in higher activity (>3.25-fold) in rat BAs with SAH. Moreover, the results of the rat double-hemorrhage model showed that the 11R-HO-1 protein significantly attenuated CV after SAH (317.59±23.48 μm (11R-HO-1) versus 270.08±14.66 μm (11R-fused enhanced green fluorescent protein), 252.05±13.95 μm (saline), P<0.01).

Reversal of cerebral vasospasm via intravenous sodium nitrite after subarachnoid hemorrhage in primates

OBJECT

Subarachnoid hemorrhage (SAH)-induced vasospasm is a significant underlying cause of aneurysm rupture-related morbidity and death. While long-term intravenous infusion of sodium nitrite (NaNO(2)) can prevent cerebral vasospasm after SAH, it is not known if the intravenous administration of this compound can reverse established SAH-induced vasospasm. To determine if the intravenous infusion of NaNO(2) can reverse established vasospasm, the authors infused primates with the compound after SAH-induced vasospasm was established.

METHODS

Subarachnoid hemorrhage-induced vasospasm was created in 14 cynomolgus macaques via subarachnoid implantation of a 5-ml blood clot. On Day 7 after clot implantation, animals were randomized to either control (saline infusion, 5 monkeys) or treatment groups (intravenous NaNO(2) infusion at 300 μg/kg/hr for 3 hours [7 monkeys] or 8 hours [2 monkeys]). Arteriographic vessel diameter was blindly analyzed to determine the degree of vasospasm before, during, and after treatment. Nitric oxide metabolites (nitrite, nitrate, and S-nitrosothiols) were measured in whole blood and CSF.

RESULTS

Moderate-to-severe vasospasm was present in all animals before treatment (control, 36.2% ± 8.8% [mean ± SD]; treatment, 45.5% ± 12.5%; p = 0.9). While saline infusion did not reduce vasospasm, NaNO(2) infusion significantly reduced the degree of vasospasm (26.9% ± 7.6%; p = 0.008). Reversal of the vasospasm lasted more than 2 hours after cessation of the infusion and could be maintained with a prolonged infusion. Nitrite (peak value, 3.7 ± 2.1 μmol/L), nitrate (18.2 ± 5.3 μmol/L), and S-nitrosothiols (33.4 ± 11.4 nmol/L) increased significantly in whole blood, and nitrite increased significantly in CSF.

CONCLUSIONS

These findings indicate that the intravenous infusion of NaNO(2) can reverse SAH-induced vasospasm in primates. Further, these findings indicate that a similar treatment paradigm could be useful in reversing cerebral vasospasm after aneurysmal SAH.

Continuous intrathecal glyceryl trinitrate prevents delayed cerebral vasospasm in the single-SAH rabbit model in vivo

BACKGROUND

Delayed cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) is a major cause of high morbidity and mortality. The reduced availability of nitric oxide (NO) in blood and cerebrospinal fluid (CSF) is well established as a key mechanism of vasospasm. Systemic administration of glyceryl trinitrate (GTN), an NO donor also known as nitroglycerin, has failed to be established in clinical settings to prevent vasospasm because of its adverse effects, particularly hypotension. The purpose of this study was to analyze the effect of intrathecally administered GTN on vasospasm after experimental SAH in the rabbit basilar artery.

METHODS

A single-hemorrhage model of SAH in rabbits was used to induce vasospasm. GTN (0.5 mg/ml) or saline was infused via a subcutaneous implanted osmotic pump with continuous drug release into the cerebellomedullary cistern over 5 days. The degree of vasospasm in the basilar artery was recorded with angiography on day 5 after SAH and was compared to baseline angiography on day 0.

FINDINGS

Significant reduction of basilar artery diameter was observed in the SAH group with saline infusion compared to sham-operated animals. Intrathecally administered GTN had no effect on the vessel diameter in sham-operated animals, whereas it significantly prevented vasospasm in the SAH group. Intrathecal GTN infusion did not affect arterial blood pressure.

CONCLUSIONS

Prophylactic, continuous intrathecal administration of GTN prevents vasospasm of the basilar artery in the rabbit SAH model. No toxic effects could be demonstrated in this study. The clinical safety and feasibility of this strategy need to be further investigated.

The role of nitric oxide donors in treating cerebral vasospasm after subarachnoid hemorrhage

Reduced intra- and perivascular availability of nitric oxide (NO) significantly contributes to the multifactorial pathophysiology of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH). The short half-life of NO demands its therapeutic substitution via NO donors. Classic NO donors such as sodium nitroprusside and nitroglycerin cannot be used as routine therapeutics because of serious side effects. Thus, a new generation of NO donors has been the subject of experimental investigations to avoid the drawbacks of the classic drugs. The purpose of this paper is to review the characteristics of different NO donors with regard to their promise and potential consequences in treating cerebral vasospasm. Additional novel concepts to increase NO concentrations, such as the activation of endothelial nitric oxide synthase (eNOS), are discussed.

A review of delayed ischemic neurologic deficit following aneurysmal subarachnoid hemorrhage: historical overview, current treatment, and pathophysiology

Delayed ischemic neurologic deficit (DIND) is a serious and poorly understood complication of aneurysmal subarachnoid hemorrhage. Although advances in treatment have improved prognosis for these patients, long-term clinical outcomes remain disappointing. Historically, angiographic vasospasm was thought to result in a DIND, although an increasing body of evidence suggests that this is an oversimplification, because interventions that have effectively targeted angiographic vasospasm have not improved outcome. Consequently, the relationship between angiographic vasospasm and neurologic outcome may be associative rather than causative. Although our understanding of the underlying molecular processes and pathophysiology is improving, responsible mediators or pathways have yet to be identified. The aim of this review is to summarize the key historical events that have helped shape our understanding of the pathophysiology of this phenomenon (microcirculation, autoregulation, microthrombosis, inflammation, apoptosis, spreading depolarization, oxidative stress) and to present the evidence underlying current treatment strategies (hemodynamic therapy, oral nimodipine, endovascular therapy, statins, cerebrospinal fluid drainage, thrombolysis, magnesium) and the translational and clinical research investigating DIND.

Treatment with transducible phosphopeptide analogues of the small heat shock–related protein, HSP20, after experimental subarachnoid hemorrhage: prevention and reversal of delayed decreases in cerebral perfusion

Object

Delayed vasospasm is a significant cause of morbidity and mortality after subarachnoid hemorrhage (SAH). Proteomic therapeutics offers a new modality in which biologically active proteins or peptides are transduced into cells via covalent linkage to cell permeant peptides (CPPs). The hypothesis of this study was that either intrathecal or intravenous delivery of a phosphopeptide mimetic of the small heat shock–related protein, HSP20, linked to a CPP, would inhibit delayed decreases in cerebral perfusion after experimental SAH in a rat model.

Methods

This study was conducted in 3 parts: 1) prevention and 2) reversal of delayed decreases in cerebral perfusion via either intrathecal or intravenous administration of a CPP linked to phosphopeptide mimetics of HSP20 (AZX100) and 3) determining the effect of intravenous administration of AZX100 on blood pressure and heart rate. Subarachnoid hemorrhage was induced in rats by endovascular perforation. Subsequently, AZX100 was administered intrathecally via a cisternal catheter or intravenously. Cerebral perfusion was determined by laser Doppler monitoring. Blood pressure was monitored by telemetry in a separate group of naïve animals treated with AZX100 for 24 hours.

Results

The maximal decrease in cerebral perfusion occurred 3 days after SAH. Cisternal administration of AZX100 (0.14–0.57 mg/kg) 24 hours after hemorrhage prevented decreases in cerebral perfusion after SAH. Animals receiving lower doses of AZX100 (0.068 mg/kg) or a scrambled sequence of the active HSP20 peptide linked to CPP developed decreases in cerebral perfusion similar to those seen in control animals. Intravenous administration of AZX100 (1.22 mg/kg) 24 hours after hemorrhage prevented the decreases in cerebral perfusion seen in the controls. Intravenous administration (0.175 mg/kg and 1.22 mg/kg) of AZX100 on Days 2 and 3 after SAH reversed decreases in cerebral perfusion as early as Day 3. There was no impact of AZX100 on blood pressure or heart rate at doses up to 2.73 mg/kg.

Conclusions

Cisternal administration of AZX100 24 hours after hemorrhage prevented decreases in cerebral perfusion. Intravenous administration of AZX100 also prevented and reversed decreases in cerebral perfusion at doses that did not induce hypotension. Transduction of biologically active motifs of downstream regulators like HSP20 represents a potential novel treatment for SAH.

Intermittent low dose intrathecal sodium nitroprusside therapy for treatment of symptomatic aneurysmal SAH-induced vasospasm

Eight patients with aneurysmal subarachnoid haemorrhage (SAH) received intrathecal sodium nitroprusside therapy (ITSNPT) in the form of intermittent bolus doses for delayed cerebral vasospasm after undergoing clipping of an aneurysm. Five patients were administered ITSNPT to combat refractory symptomatic vasospasm while three patients received prophylactic ITSNPT in view of the possibility of imminent clinical vasospasm. In five patients the therapy was instituted through the intraventricular route, while in three the drug was instilled into the basal cistern. Sodium nitroprusside (SNP) was administered at an interval of 3-12 h, in varying bolus doses ranging between 2 and 5 mg depending upon the (i) mean flow velocity values on transcranial Doppler study and (ii) clinical response. The end point of ITSNPT was either relief of vasospasm, any adverse effect or contraindication to continuation of ITSNPT. All except one patient survived. One patient had mild residual neurological deficit following an infarct. All the three patients who received prophylactic ITSNPT had good outcomes.

Endothelial nitric oxide synthase tagging single nucleotide polymorphisms and recovery from aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a hemorrhagic stroke subtype with a poor recovery profile. Cerebral vasospasm (CV), a narrowing of the cerebral vasculature, significantly contributes to the poor recovery profile. Variation in the endothelial nitric oxide (NO) synthase (eNOS) gene has been implicated in CV and outcome after SAH. The purpose of this project was to explore the potential association between three eNOS tagging single nucleotide polymorphisms (SNPs) and recovery from SAH. We included 195 participants with a diagnosis of SAH and DNA and 6-month outcome data available but without preexisting neurologic disease/deficit. Genotyping was performed using an ABI Prism 7000 Sequence Detection System and TaqMan assays. CV was verified by cerebral angiogram independently read by a neurosurgeon on 118 participants. Modified Rankin Scores (MRS) and Glasgow Outcome Scale (GOS) scores were collected 6 months posthemorrhage. Data were analyzed using descriptive statistics, analysis of variance (ANOVA) and chi-square analysis as appropriate. The sample was primarily female (n=147; 75.4%) and White (n=178; 91.3%) with a mean age of 54.6 years. Of the participants with CV data, 56 (47.5%) developed CV within 14 days of SAH. None of the SNPs individually were associated with CV presence; however, a combination of the three variant SNPs was significantly associated with CV (p=.017). Only one SNP (rs1799983, variant allele) was associated with worse 6-month GOS scores (p<.001) and MRS (p<.001). These data indicate that the eNOS gene plays a role in the response to SAH, which may be explained by an influence on CV.

A review of medical treatments of cerebral vasospasm

We review the literature on the established perioperative therapies for cerebral vasospasm (CV) following aneurysmal subarachnoid hemorrhage (aSAH). Despite aSAH treatment advances, CV continues to be a significant source of post-SAH morbidity and mortality. In fact, CV has been correlated with a 7.5- to three-fold increase in mortality in the first 2 weeks after SAH. As new treatment modalities show promise in animal models and early clinical trials, greater efforts are needed to test these new approaches. Few evidence-based indications for the treatment of vasospasm currently exist. Large-scale randomized clinical trials are needed to determine whether therapies such as magnesium, statins, nitric oxide modulators, endothelin antagonists and others will become standard of care in the prevention and/or treatment of CV.

CONTROVERSIES IN THE ENDOVASCULAR MANAGEMENT OF CEREBRAL VASOSPASM AFTER INTRACRANIAL ANEURYSM RUPTURE AND FUTURE DIRECTIONS FOR THERAPEUTIC APPROACHES

CEREBRAL VASOSPASM IS one of the leading causes of morbidity and mortality after aneurysmal subarachnoid hemorrhage. Despite maximal medical therapy, however, up to 15% of patients surviving the ictus of subarachnoid hemorrhage experience stroke or death from vasospasm. For those cases of vasospasm that are refractory to medical treatment, endovascular techniques are frequently used, including balloon angioplasty with or without intra-arterial infusion of vasodilators, combined endovascular modalities, and aortic balloon devices. In this article, we review each of these therapies and their expanding role in the management of this condition. Moving forward, rigorous prospective outcome assessments after endovascular treatment of cerebral vasospasm are necessary to clearly delineate the efficacy and indications for these techniques.

Intensive care management of patients with subarachnoid haemorrhage

PURPOSE OF REVIEW

The aim of this article is to summarize recent concepts regarding the intensive care management of patients with subarachnoid haemorrhage, emphasizing the detection and treatment of cerebral vasospasm and the management of systemic complications.

RECENT FINDINGS

Aneurysmal subarachnoid haemorrhage is a potentially devastating disease that requires complex treatment strategies and extended monitoring. The prognosis of subarachnoid haemorrhage depends on the severity of the initial bleed, the success of the procedure to secure the aneurysm and the occurrence and severity of sequelae, including cerebral vasospasm. Patients with subarachnoid haemorrhage benefit from multidisciplinary neurointensive care where management is targeted at securing the ruptured aneurysm, optimizing cardiovascular variables, detecting and treating cerebral vasospasm and managing systemic complications.

SUMMARY

The complex treatment strategies applied after subarachnoid haemorrhage call for interdisciplinary collaboration between neurosurgeons, neuroradiologists, neurointensivists and specialist nurses. Specialized neuromonitoring and neuroimaging techniques must also be available. The neurointensive care unit serves as the focal point for these combined efforts.

[Endovascular treatment of vasospasm following subarachnoid aneurysmal haemorrhage]

An endovascular treatment of vasospasm following a subarachnoid aneurysmal haemorrhage is to be implemented if the patient presents clinical or biological symptoms arguing for brain ischemia in conjunction with increased Doppler velocities despite well controlled systemic haemodynamic. Treatment might be either pharmacological or haemodynamic. Calcium and phosphodiesterase inhibitors can be administered. The former could also provide a neuroprotective effect as compared to the latter. In Europe, nimodipine is widely used whereas nicardipine and verapamil are the major molecules administered in North America where iv nimodipine is not FDA approved. Papaverine is less used nowadays because of its short duration of action and of the risk of aggravation of raised intracranial pressure. Balloon angioplasty has a long lasting effect but can be applied only to proximal spasm. Complications of its use are rare but life threatening. In some cases, both the pharmacological approach and the mechanical approach are used in combination.

Advances in vasospasm treatment and prevention

Outcome after aSAH depends on several factors, including the severity of the initial event, perioperative medical management, surgical variables, and the incidence of complications. Cerebral vasospasm (CV) is ure to consistently respond to treatment, emphasizing the need for further research into the underlying mechanisms of SAH-induced cerebrovascular dysfunction. To this end, our paper reviews the relevant literature on the main therapies employed for CV after aSAH and discusses possible avenues for future investigations. Current management of this condition consists of maximal medical therapy, including triple H regimen and oral administration of calcium antagonists, followed by endovascular balloon angioplasty and/or injection of vasodilatory agents for refractory cases. As the precise pathophysiology of CV is further elucidated, the development of promising investigational therapies will follow.

Endovascular management of intracranial aneurysms: current experience and future advances

OBJECTIVE

The past 15 years have seen a revolution in the treatment of intracranial aneurysms. Endovascular technology has evolved rapidly since the Food and Drug Administration approval of Guglielmi detachable coils in 1995, which now allows successful treatment of most aneurysms. The authors provide a review of their 11-year experience at Jefferson Hospital for Neuroscience with endovascular embolization of intracranial aneurysms and discuss clinical trial outcomes and future directions of this treatment method.

METHODS

The authors reviewed the clinical and angiographic outcomes for 1307 patients undergoing endovascular treatment of intracranial aneurysms. Their analysis focuses on posterior circulation and middle cerebral artery aneurysms, as well as cases of stent-assisted coil embolization. They review their procedural protocol and patient selection criteria for endovascular management.

RESULTS

Several large clinical trials have demonstrated the safety and efficacy of endovascular treatment of intracranial aneurysms. The International Subarachnoid Aneurysm Trial provides Level I evidence demonstrating a significant reduction in disability or death with endovascular treatment compared with surgical clipping. The most common procedural complications include intraprocedural rupture and thromboembolic events; avoidance strategies are also discussed. Vasospasm after subarachnoid hemorrhage causes neurological morbidity and mortality and can be successfully managed by early recognition and interventional treatment with angioplasty, pharmacologic agents, or both.

CONCLUSION

Long-term studies evaluating experience with aneurysm coil embolization during the past decade indicate that this is a safe and durable treatment method. The introduction of stent-assist techniques has improved the management of wide-neck aneurysms. Future technology developments will likely improve the durability of endovascular treatment further by delivering bioactive agents that promote aneurysm thrombosis beyond the coil mass alone. It is clear that endovascular therapy of both ruptured and unruptured aneurysms is becoming a mainstay of practice in this patient population. Although not replacing open surgery, the continued improvements have allowed aneurysms that previously were amenable only to open clip ligation to be treated safely with durable long-term outcomes.

PERSISTENCE OF THE NITRIC OXIDE-DEPENDENT VASODILATORPATHWAY OF CEREBRAL VESSELS AFTEREXPERIMENTAL SUBARACHNOID HEMORRHAGE

OBJECTIVE

Efficiency of the treatment of cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH) by interfering with the nitric oxide-cyclic guanosine monophospate (cGMP) pathway seems to be inconsistent. So far, it remains unclear whether or not insufficient access to the drugs or impaired reactivity of the vessels is responsible for this inconsistency. Therefore, the aim of the present investigation was to characterize this pathway on cerebral arteries during CVS.

METHODS

CVS was induced using the rat double hemorrhage model and was determined by magnetic resonance perfusion weighted imaging. Rats were sacrificed on Day 3 and Day 5 after SAH. Immunohistochemical staining of the basilar artery for endothelial nitric oxide synthases and the alpha- and beta-subunits of the soluble guanylate cyclase was performed. Basilar artery ring segments on Day 5 were used for measurement of isometric force. Concentration effect curves for acetylcholine, sodium nitroprusside, and 8-bromo-cGMP were constructed and compared by maximum effect and pD2.

RESULTS

The immunohistochemical expression of endothelial nitric oxide synthase was comparable in all groups. The soluble guanylate cyclase alpha- and beta-subunits were significantly diminished on Day 3, but recovered by Day 5. The relaxation attributable to acetylcholine and 8-bromo-cGMP was virtually identical in controls and during CVS. Relaxation attributable to sodium nitroprusside, however, was significantly enhanced after SAH (maximum effect, control: 88 +/- 12%; Day 5: 117 +/- 26%).

CONCLUSION

The present investigations suggest the persistence of endothelium-, nitric oxide-, and cGMP-dependent relaxation during CVS. Therefore, the treatment of CVS interfering with this pathway seems not to be limited by alterations inside the vessel wall.

A review of current and future medical therapies for cerebral vasospasm following aneurysmal subarachnoid hemorrhage

✓In an effort to help clarify the current state of medical therapy for cerebral vasospasm, the authors reviewed the relevant literature on the established medical therapies used for cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH), and they discuss burgeoning areas of investigation. Despite advances in the treatment of aneurysmal SAH, cerebral vasospasm remains a common complication and has been correlated with a 1.5- to threefold increase in death during the first 2 weeks after hemorrhage. A number of medical, pharmacological, and surgical therapies are currently in use or being investigated in an attempt to reverse cerebral vasospasm, but only a few have proven to be useful. Although much has been elucidated regarding its pathophysiology, the treatment of cerebral vasospasm remains a dilemma. Although a poor understanding of SAH-induced cerebral vasospasm pathophysiology has, to date, hampered the development of therapeutic interventions, current research efforts promise the eventual production of new medical therapies.

Vasospasm in Glaucoma: Clinical and Laboratory Aspects

During the last decade, the presumed etiology of glaucoma has moved from a pure pressure concept to a combined mechanical and vascular theory. Evidence of a localized vascular insufficiency leading to perfusion deficits of ocular structures, including the optic nerve head, the retina, the choroid, and the retrobulbar vessels, is now clear. This article evaluates the role of vasospasm as the primary cause of such a vascular failure. The role of both ocular and systemic vasospasms and their clinical correlations are discussed. At a cellular level, the function of the modulating role of the vascular endothelium is reviewed. Evidence of abnormalities of the vascular endothelium and its vasoactive peptides as a conduit for vasospasm is mounting. Herein lies exciting prospects for potential pharmacologic targets in future glaucoma management.

Safe and efficient drug delivery system with liposomes for intrathecal application of an antivasospastic drug, fasudil

Pharmacological treatment for cerebral ischemia and cerebral vasospasm following subarachnoid hemorrhage (SAH) cannot attain sufficiently high concentrations of the drugs in the cerebrospinal fluid (CSF) without precipitating systemic side effects. We recently developed a liposomal drug delivery system for intrathecal application that can maintain effective concentrations of cerebral vasodilator, fasudil, in the CSF. A single intrathecal injection of liposomal fasudil could maintain a therapeutic drug concentration in the CSF over a period time due to their sustained-release property, significantly decreasing infarct size in a rat model of acute ischemia and reducing vasoconstriction of the rat and dog basilar artery in a model of SAH. In this review, we are introducing our new less-invasive intrathecal drug delivery system that provides an alternative and safe method to deliver therapeutic agents.

Detecting and treating microvascular ischemia after subarachnoid hemorrhage

PURPOSE OF REVIEW

To provide an overview of the current management of cerebral vasospasm following subarachnoid hemorrhage, emphasizing the detection and treatment of delayed ischemia.

RECENT FINDINGS

Sensitive and specific monitoring methods are necessary to register the onset of cerebral vasospasm early to prevent long-term morbidity and mortality. Therefore, various techniques to measure cerebral perfusion and/or surrogate parameters have been developed. Prophylaxis with calcium antagonists such as nimodipine is administered for neuroprotection. Resolution of ongoing cerebral vasospasm can be achieved by either dilating constricted vessels or optimizing hemodynamics. Therapeutic treatment with hypertension, hypervolemia and hemodilution (HHH) has a direct influence on cerebral vasospasm, ischemic sequelae and outcome, while prophylactic HHH leads to excess complications. Other treatments, for example endothelin antagonists, statins or magnesium salts, used to prevent or treat cerebral vasospasm, are being tested. Endovascular treatment options can be used for therapy-refractory cerebral vasospasm, but they carry procedure-related risks and may be short-acting.

SUMMARY

Diagnosis of microvascular ischemia following subarachnoid hemorrhage involves clinical observation, non-invasive determination of cerebral hemodynamic variables, autoregulation studies and invasive online monitoring of cerebral oxygenation and metabolism. Nimodipine is administered prophylactically, while HHH is initiated therapeutically. New causal therapies are being evaluated.

Controlled release of a nitric oxide donor for the prevention of delayed cerebral vasospasm following experimental subarachnoid hemorrhage in nonhuman primates

OBJECT

Results of prior studies in rats and rabbits show that the alteration of vasomotor tone in vasospasm following periadventitial blood exposure may be reversed, at least in part, by the administration of compounds releasing nitric oxide (NO). The authors have now generalized this finding to nonhuman primates.

METHODS

Ten cynomolgus monkeys underwent cerebral angiography before and 7 days following the induction of subarachnoid hemorrhage (SAH) by the placement of 2 to 3 ml clotted autologous blood around the supraclinoid carotid, proximal anterior cerebral, and proximal middle cerebral arteries. An ethylene vinyl acetate copolymer, either blank (five animals) or containing 20% w/w (Z)-1-[2-(2-aminoethyl)-N-(2-aminoethyl)amino]diazen-1-ium-1,2-diolate (DETA/NO, 4.3 mg/kg; five animals) was placed adjacent to the vessels at the time of surgery. Animals were killed on Day 7 post-SAH following repeated cerebral angiography. The mean percentage of control vascular areal fraction was calculated from angiograms. Cerebral vessels were sectioned and the mean percentage of lumen patency was calculated. One animal that had received the DETA/NO polymer died prior to repeated angiography. In the remaining animals, DETA/NO caused a significant decrease in vasospasm compared with controls, according to both angiographic (84.8 +/- 8.6 compared with 56.6 +/- 5.2%, respectively, p < 0.05) and histological studies (internal carotid artery 99.3 +/- 1.8 compared with 60.1 +/- 4.4%, respectively, p < 0.001; middle cerebral artery 98.4 +/- 3 compared with 56.1 +/- 3.7%, respectively, p < 0.001; and anterior cerebral artery 89.2 +/- 8.5 compared with 55.8 +/- 6.3%, respectively, p < 0.05).

CONCLUSIONS

The controlled release of DETA/NO is effective in preventing delayed cerebral vasospasm in an SAH model in nonhuman primates. The death of one animal in the treatment group indicates that the present dosage is at the threshold between therapeutic efficacy and toxicity.

Cerebrovascular effects of sodium nitroprusside in the anaesthetized baboon: a positron emission tomographic study

The effects of sodium nitroprusside (SNP), a potent hypotensive agent, on cerebral blood flow (CBF) have been extensively studied in clinical and experimental situations but the results remain controversial. Whereas its properties would predict a dilatation of cerebral blood vessels, most studies report either no change or a decrease in CBF. The aim of this study was to investigate the effects of SNP on CBF, cerebral blood volume (CBV), and cerebral oxygen metabolism (CMRO2), by means of positron emission tomography in the anaesthetized baboon. Measurements were performed during normotension (mean arterial pressure (MABP): 97+/-16 mm Hg) and repeated following SNP-induced hypotension (MABP: 44+/-9 mm Hg). Sodium nitroprusside led to an increase in CBF and CBV (+30% and +37%, respectively, P<0.05), whereas no change in CMRO2 was noted. Linear regression analysis of CBF values as a function of MABP confirmed that CBF increases when MABP is reduced by SNP. The comparison between these cerebrovascular changes and those found during trimetaphan-induced hypotension in our previously published studies further argues for a direct dilatatory effect of SNP on cerebral blood vessels.

Intraoperative microvascular Doppler in intracranial aneurysm surgery

OBJECTIVE

The usefulness of intraoperative microvascular Doppler (IMD) in preventing an incorrect placement of the clip during intracranial aneurysm surgery is described. Such incorrect placement of the clip may cause new bleeding or ischemic accident as a consequence of incomplete exclusion of the aneurysm or stenosis/occlusion of the parent and/or adjacent arteries.

METHODS

One hundred thirty patients, harboring 136 aneurysms, were operated on using IMD. IMD study was performed on the aneurysm and adjacent arterial vessels before and after the clip placement. Mechanical arterial spasm was treated by topical sodium nitroprusside (SNP) and its efficacy verified by IMD.

RESULTS

In 55 aneurysms (42.3%), IMD was helpful in understanding the microvascular anatomy before clip placement. Complete exclusion resulted in 129 aneurysms (94.9%). In 5 cases (3.7%) in which IMD revealed a persistent blood flow in the aneurysm, the clip was repositioned. In 2 cases (1.4%), we obtained false-negative results. In 25 cases (18.3%) in which IMD data documented a severe flow reduction in the vessel harboring the aneurysm or in the vessel originating very close to the aneurysm neck, the clip was repositioned. There were no complications due to the use of IMD. In 20 patients (15%) in which IMD revealed arterial spasm by surgical manipulation, topical SNP was followed by resolution of the spasm.

CONCLUSION

IMD is a feasible, safe, and very reliable technique in aneurysm surgery. Compared to other procedures such as intraoperative angiography, the cost efficiency of IMD is favorable.

Effect of Prior Statin Use on Functional Outcome and Delayed Vasospasm after Acute Aneurysmal Subarachnoid Hemorrhage: A Matched Controlled Cohort Study

OBJECTIVE

Hydroxymethylglutaryl coenzyme A reductase inhibitors (statins), which exhibit beneficial cerebrovascular effects by modulating inflammation and nitric oxide production, have not been evaluated in acute aneurysmal subarachnoid hemorrhage (SAH) patients. The effect of prior statin use on 14-day functional outcome and on prevention of vasospasm-induced delayed cerebral ischemia (DCI) or stroke during hospitalization was analyzed.

METHODS

We conducted a 1:2 matched (age, admission Hunt and Hess grade, vascular disease/risk history) cohort study of 20 SAH patients on statins and 40 SAH controls. The primary outcome was functional outcome at 14 days (Modified Lawton Physical Self-Maintenance Scale and Barthel Index scale scores). Secondary outcomes were 14-day mortality, Modified Rankin Scale score, DCI, DCI supported by angiography/transcranial Doppler [TCD], cerebral infarctions of any type, and TCD highest mean velocity elevation.

RESULTS

Statin users demonstrated a significant protective effect on 14-day Barthel Index scale and Modified Lawton Physical Self-Maintenance Scale scores (77 +/- 10 versus 39 +/- 8, P = 0.003; 12 +/- 7 versus 19 +/- 9, P = 0.03, respectively). Moreover, statin users demonstrated a significantly lower incidence of DCI and DCI supported by angiography/TCD (10% versus 43%, P = 0.02; 5% versus 35%, P = 0.01, respectively), cerebral infarctions of any type (25% versus 63%, P = 0.01), and baseline-to-final TCD highest mean velocity change of 50 cm/s or greater (18% versus 51%, P = 0.03).

CONCLUSION

SAH statin users demonstrated significant improvement in 14-day functional outcome, a significantly lower incidence of DCI and cerebral infarctions of any type, as well as prevention of TCD highest mean velocity elevation. However, we did not find a significant statin impact on mortality or global outcome (Modified Rankin Scale) in this small sample. This study provides clinical evidence for the potential therapeutic benefit of statins after acute SAH.

The effect of subarachnoid sodium nitroprusside on the prevention of vasospasm in subarachnoid haemorrhage

OBJECTIVE

The aim of this study was to evaluate the effect of preventive and therapeutic use of subarachnoid sodium nitroprusside (SNP) administration in patients with non-traumatic subarachnoid haemorrhage (SAH).

METHODS

All consecutive adult patients admitted in the period 2000-2003 with SAH, Hunt-Hess grade I-IV, indicated for neurosurgical intervention, were enrolled in the study. In the postoperative period they were treated with mechanical ventilation and triple H protocol with nimodipine. Subarachnoid preventive SNP was administred in initial dose of 1 mg by catheter inserted into basal cisterns during the neurosurgical procedure. The timing of following dosage was directed by the changes of respiratory parameters of brain tissue in the region of interest by multiparameter sensor (Codman Neurotrend) and findings of blood flow velocity on the level of circle of Willis were measured by transcranial doppler ultrasonography (TCD).

RESULTS

17 patients were enrolled to study. All patients survived. No brain infarction developed. The increase blood flow velocity was found in three patients.

CONCLUSION

Preventive subarachnoid use of SNP in combination with multimodal monitoring might be a possible preventive strategy. Its efficacy has to be proved on a greater group of patients in the future. The therapeutical use of SNP requires an increase in application rate.

Development of Drug Delivery System for Intrathecal Administration and Its Therapeutic Effect on Cerebral Vasospasm and Ischemia

To date, the pharmacologic approach to cerebral vasospasm and ischemia has been hampered in part by an inability to attain sufficiently high concentrations of drugs in the cerebrospinal fluid (CSF). To overcome this limitation of current drug therapy, we have developed a sustained-release preparation of the protein kinase inhibitor fasudil. Experimental cerebral vasospasm in rats and dogs was induced by double injection of autologous arterial blood into the cisterna magna. Focal cerebral ischemia in rats was induced by middle cerebral artery occlusion using an intraluminal suture technique. A single intrathecal injection of liposomal fasudil can maintain a therapeutic the drug concentration in the CSF due to the sustained-release property of liposomes, significantly decreasing intact size of acute ischemia and decreasing vasoconstriction of the basilar artery in cerebral vasospasm. This novel approach for the treatment of cerebral vasospasm and ischemia may have significant potential for use in the clinical setting.