Does Prevention of Vasospasm in Subarachnoid Hemorrhage Improve Clinical Outcome? Yes

Effects of clazosentan on cerebral vasospasm-related morbidity and all-cause mortality after aneurysmal subarachnoid hemorrhage: two randomized phase 3 trials in Japanese patients

OBJECTIVE

Clazosentan has been investigated globally for the prevention of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH). The authors evaluated its effects on vasospasm-related morbidity and all-cause mortality following aSAH in Japanese patients.

METHODS

Two similar double-blind, placebo-controlled phase 3 studies were conducted in 57 Japanese centers in patients with aSAH, after aneurysms were secured by endovascular coiling in one study and surgical clipping in the other. In each study, patients were randomly administered intravenous clazosentan (10 mg/hr) or placebo (1:1) starting within 48 hours of aSAH and for up to 15 days after aSAH. Stratified randomization based on World Federation of Neurosurgical Societies grade was performed using a centralized interactive web response system. Vasospasm-related morbidity and all-cause mortality within 6 weeks post-aSAH, including new cerebral infarcts and delayed ischemic neurological deficits as well as all-cause mortality, were the first primary endpoint in each study. The second primary endpoint was all-cause morbidity (new cerebral infarct or delayed ischemic neurological deficit from any causes) and all-cause mortality (all-cause morbidity/mortality) within 6 weeks post-aSAH. The incidence of individual components of the primary morbidity/mortality endpoints within 6 weeks and patient outcome at 12 weeks post-aSAH (including the modified Rankin Scale scores) were also evaluated. The above analyses were also performed in the population pooled from both studies.

RESULTS

In each study, 221 patients were randomized and 220 were included in the full analysis set of the primary analysis (109 in each clazosentan group, 111 in each placebo group). Clazosentan significantly reduced the incidence of vasospasm-related morbidity and all-cause mortality after aneurysm coiling (from 28.8% to 13.6%; relative risk reduction 53%; 95% CI 17%-73%) and after clipping (from 39.6% to 16.2%; relative risk reduction 59%; 95% CI 33%-75%). All-cause morbidity/mortality and poor outcome (dichotomized modified Rankin Scale scores) were significantly reduced by clazosentan after preplanned study pooling. Treatment-emergent adverse events were similar to those reported previously.

CONCLUSIONS

Clazosentan significantly reduced the combined incidence of vasospasm-related morbidity and all-cause mortality post-aSAH with no unexpected safety findings. Clinical trial registration nos.: JapicCTI-163368 and JapicCTI-163369 (https://www.clinicaltrials.jp).

Correlation between Arteriole Membrane Potential and Cerebral Vasospasm after Subarachnoid Hemorrhage in Rats

Objectives

Microvessel constriction plays an important role in delayed cerebral ischemia after aneurismal subarachnoid hemorrhage (SAH). This constriction has been demonstrated in both animal model and clinical operation. The present study examined the time-related membrane potential (Em) alteration of arterioles isolated from SAH model rats and the correlation between the potential alteration of arterioles and the diameter of basilar artery.

Materials and Methods

Sprague-Dawley rats (n = 90), weighing 300 g to 350 g, were divided into t control, sham, and SAH groups. In the SAH group, blood was injected into the prechiasmatic cistern of the rats. The Em of arterioles and basilar artery diameter was measured using whole-cell clamp recordings and pressure myograph, respectively, 1, 3, 5, 7, and 14 days after SAH. The correlation was evaluated using Pearson correlation coefficients.

Results

The Em of arterioles in the SAH group depolarized on days 3, 5, and 7, and peaked on day 7. The diameters significantly decreased on days 1, 3, 5, 7, and 14, and the smallest diameter was observed on day 7. A significant correlation between potential alteration of arterioles and diameter of basilar artery was found.

Conclusions

Similar to the artery, arteriole constriction is also involved in the pathophysiological events of delayed cerebral ischemia.

Severity of cerebral vasospasm associated with development of collaterals following aneurysmal subarachnoid hemorrhage

Introduction

Cerebral collateral circulation has been studied extensively in ischemic stroke where it has been shown to be a predictor of reperfusion, final infarct size, and outcome. Little is known about the significance of the collaterals in the setting of aneurysmal subarachnoid hemorrhage (aSAH). We sought to evaluate the effect of cerebral vasospasm on the development of cerebral collaterals following aneurysmal subarachnoid hemorrhage and the effects of the latter on delayed cerebral ischemia (DCI).

Methods

We retrospectively evaluated 64 aSAH patients with evidence of DCI between day 5 and 7, enrolled in a prospectively maintained observational cohort study. Angiograms were evaluated by four blinded neurointerventionalists. We compared good collateral grades to poor collateral grades, additionally we compared enrolled individuals with any collaterals versus patients who had no collaterals.

Results

Inter-rater reliability for collateral grades was substantial (weighted kappa 0.632). Mild vasospasm was more frequent in patients with poor collateral grades compared with patients with good collateral grades (32% vs 4% P=0.012). There was no difference between the collateral groups with regards to DCI, functional, or cognitive outcome. Patients adjudicated to have any collaterals were more likely to have severe vasospasm (62% vs 33% P=0.023) and less likely to have mild vasospasm (37% vs 9% P=0.007). In a multivariable model, vasospasm severity remained associated with collateral status, while aneurysm location was not.

Conclusions

The severity of vasospasm following aSAH was associated with the development of collaterals. There was no difference between collateral grades with regards to DCI or outcome.

Subarachnoid hemorrhage - Induced block of cerebrospinal fluid flow: Role of brain coagulation factor III (tissue factor)

Subarachnoid hemorrhage (SAH) in 95% of cases results in long-term disabilities due to brain damage, pathogenesis of which remains uncertain. Hindrance of cerebrospinal fluid (CSF) circulation along glymphatic pathways is a possible mechanism interrupting drainage of damaging substances from subarachnoid space and parenchyma. We explored changes in CSF circulation at different time following SAH and possible role of brain tissue factor (TF). Fluorescent solute and fluorescent microspheres injected into cisterna magna were used to track CSF flow in mice. SAH induced by perforation of circle of Willis interrupted CSF flow for up to 30 days. Block of CSF flow did not correlate with the size of hemorrhage. Following SAH, fibrin deposits were observed on the brain surface including areas without visible blood. Block of astroglia-associated TF by intracerebroventricular administration of specific antibodies increased size of hemorrhage, decreased fibrin deposition and facilitated spread of fluorophores in sham/naïve animals. We conclude that brain TF plays an important role in localization of hemorrhage and also regulates CSF flow under normal conditions. Targeting of the TF system will allow developing of new therapeutic approaches to the treatment of SAH and pathologies related to CSF flow such as hydrocephalus.

Functional response of cerebral blood flow induced by somatosensory stimulation in rats with subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is often accompanied by cerebral vasospasm (CVS), which is the phenomenon of narrowing of large cerebral arteries, and then can produce delayed ischemic neurological deficit (DIND) such as lateralized sensory dysfunction. CVS was regarded as a major contributor to DIND in patients with SAH. However, therapy for preventing vasospasm after SAH to improve the outcomes may not work all the time. It is important to find answers to the relationship between CVS and DIND after SAH. How local cerebral blood flow (CBF) is regulated during functional activation after SAH still remains poorly understood, whereas, the regulation of CBF may play an important role in weakening the impact of CVS on cortex function. Therefore, it is worthwhile to evaluate the functional response of CBF in the activated cortex in an SAH animal model. Most evaluation of the effect of SAH is presently carried out by neurological behavioral scales. The functional imaging of cortical activation during sensory stimulation may help to reflect the function of the somatosensory cortex more locally than the behavioral scales do. We investigated the functional response of CBF in the somatosensory cortex induced by an electrical stimulation to contralateral forepaw via laser speckle imaging in a rat SAH model. Nineteen Sprague-Dawley rats from two groups (control group, n=10 and SAH group, n=9) were studied. SAH was induced in rats by double injection of autologous blood into the cisterna magna after CSF aspiration. The same surgical procedure was applied in the control group without CSF aspiration or blood injection. Significant CVS was found in the SAH group. Meanwhile, we observed a delayed peak of CBF response in rats with SAH compared with those in the control group, whereas no significant difference was found in magnitude, duration, and areas under curve of relative CBF changes between the two groups. The results suggest that the regulation function of local CBF during functional activation induced by somatosensory stimulation might not be seriously impaired in the somatosensory cortex of rats with SAH. Therefore, our findings might help to understand the clinical phenomenon that DIND might not occur even when CVS was found in SAH patients.

Delayed infarction following aneurysmal subarachnoid hemorrhage: Can the role of severe angiographic vasospasm really be dismissed?

Background

The recent literature pertaining to delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage has downplayed the role of angiographic vasospasm. However, it is our hypothesis that angiographic vasospasm has a significant pathophysiological role in this disease. We undertook an observational radiographic study of patients who presented in a delayed manner (>72 h from ictus) with evidence of severe angiographic vasospasm on initial angiography in order to describe an apparent association between vasospasm and infarct location.

Methods

This was a retrospective study of consecutive patients treated at our unit. Initial, subsequent, and follow-up cross-sectional imaging with CT or MRI was analyzed in conjunction with initial angiography. Sites of angiographic narrowing, angiographic hypoperfusion, and subsequent sites of infarction were assessed.

Results

Thirteen patients (6 women, 7 men) of mean age 49 years were assessed. Mean time to presentation was 6 days. All had severe angiographic vasospasm. Nine of the 13 patients suffered infarction; the infarcts in seven of the nine patients were large. There was correlation between sites of angiographic narrowing and infarction in all cases and eight of the nine cases showed angiographic hypoperfusion in a location corresponding to eventual infarct location.

Conclusions

Severe angiographic vasospasm may be linked to infarction in patients who present late. These infarcts are mostly large despite maximal treatment. We question the notion that proximal vasospasm has a minor role in delayed ischemia.

Institution of sustained endovascular treatment prior to clinical deterioration in patients with severe angiographic vasospasm: A retrospective observational study of clinico-radiological outcomes

Severe angiographic vasospasm (aVSP) is a risk factor for infarction following subarachnoid haemorrhage and infarction is strongly associated with poor outcome. We present the clinico-radiological results of cohort with severe aVSP who underwent a program of angiographic surveillance and sustained endovascular treatment using multiple verapamil infusions and/or transluminal balloon angioplasty (TBA).

METHODS

This was a dual-centre retrospective observational study. Angiographic screening for vasospasm was undertaken at days 5-7 post-ictus. Treatment was instituted principally on the basis of radiographic findings. The rate of infarction was evaluated on follow-up CT. Clinical outcome was assessed using the modified Rankin Scale (mRS).

RESULTS

Fifty-seven WFNS grades 1-5 patients were studied. The mean number of procedures/patient was 6, range 2-13. Mean verapamil dose administered to the ICA was 14 mg and VA was 12 mg. Thirty-one patients underwent TBA (52.6%). The rate of proximal vessel infarction was 3/45 (6.7%) for patients presenting <72 hours. Rates of favourable outcome (mRS 0-2) were 16/19 (84.2%) for WFNS grades 1-2, 12/19 (63.2%) for grades 3-4 and 5/19 (26.3%) for grade 5 patients. Delayed presentation >72 hours was the only factor on multivariate analysis to significantly predict aVSP-infarction [OR19.3 (3.2-116.6) P=0.0012]. Large aVSP-infarction [OR19.0 (1.7-216.4) 0.0179] and poor WFNS grade [OR 6.6 (1.3-33.9) P = 0.0233] were significant predictors of poor outcome on multivariate analysis.

CONCLUSION

This approach may result in low rates of aVSP-infarction and encouraging rates of favourable outcome when compared to literature benchmarks. Delayed presentation, however, predicts infarction and large infarct and poor initial grade significantly influence functional outcome.

Expression of suppressor of cytokine signaling 3 in cerebrospinal fluid after subarachnoid hemorrhage

BACKGROUND

IL-6 is a proinflammatory cytokine reported to play an important role in the induction of cerebral vasospasm after subarachnoid hemorrhage (SAH). Suppressor of cytokine signaling 3 (SOCS3) is known to act as an inhibitor of signal transduction of IL-6. However, there have been no reports on the expression of SOCS3 in cerebrospinal fluid (CSF) after SAH.

FINDINGS

The concentration of IL-6 was measured serially up until day 10, in CSF of eight patients with SAH. CSF samples obtained from patients suffering from an unruptured aneurysm were used as controls. The expression of SOCS3 in CSF was further examined by immunoprecipitation methods. Concentrations of IL-6 in CSF increased immediately after the onset of SAH and remained chronically elevated over control values. SOCS3 was significantly expressed in CSF on days 1 to 3 after SAH.

CONCLUSIONS

Our findings suggest that SOCS3 regulates IL-6 signaling as an antagonist in CSF, immediately following SAH. As the expression of SOCS3 decreases after day 5, IL-6 signals might then be more easily transmitted, presumably resulting in cerebral vasospasm.

Genetic elimination of Nrf2 aggravates secondary complications except for vasospasm after experimental subarachnoid hemorrhage in mice

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key endogenous protective regulator in the body. This study aimed to explore the role of Nrf2 in subarachnoid hemorrhage (SAH)-induced secondary complications. Wild type (WT) and Nrf2 knockout (KO) mice were subjected to experimental SAH by injecting fresh autologous blood into pre-chiasmatic cistern. The absence of Nrf2 function in mice resulted in exacerbated brain injury with increased brain edema, blood-brain barrier (BBB) disruption, neural apoptosis, and severe neurological deficits at 24h after SAH. Moreover, cerebral vasospasm was severe at 24h after SAH, but not significantly different between WT and Nrf2 KO mice after SAH. Meanwhile, Molondialdehyde (MDA) was increased and GSH/GSSG ratio was decreased in Nrf2 KO mice after SAH. Furthermore, higher expression of TNF-α and IL-1β was also found after SAH in Nrf2 KO mice. In conclusion, our results revealed that Nrf2 plays an important role in attenuating SAH-induced secondary complications by regulating excessive oxidative stress and inflammatory response.