Delayed cerebral ischemia and spreading depolarization in absence of angiographic vasospasm after subarachnoid hemorrhage

Intimal Hemorrhage of Basilar Artery Induced by Severe Vasospasm Following Subarachnoid Hemorrhage: The Experimental Analysis

BACKGROUND

 Cerebral vasospasm, a serious complication of subarachnoid hemorrhage (SAH), has been extensively studied for its neurochemical and pathophysiologic mechanisms. However, the contribution of inner elastic membrane dissection and subintimal hemorrhage to basilar artery occlusion remains underexplored. This study investigates inner elastic membrane-related changes in the basilar artery after SAH.

METHODS

 Twenty-four hybrid rabbits were divided into control, sham, and SAH groups, with SAH induced by autologous blood injection. After 2 weeks, basilar artery changes, vasospasm indexes (VSIs), and dissections were evaluated.

RESULTS

 The SAH group showed significantly higher VSI, with vascular wall thickening, luminal narrowing, convoluted smooth muscle cells, intimal elastic membrane disruption, endothelial cell desquamation, and apoptosis. Some SAH animals exhibited subintimal hemorrhage, inner elastic membrane dissection, and ruptures. Basilar arteries with subintimal hemorrhage had notably higher VSI.

CONCLUSIONS

 These findings highlight the role of subintimal hemorrhage and inner elastic membrane dissection in basilar artery occlusion post-SAH, offering valuable insights into vasospasm pathophysiology.

All Three Supersystems-Nervous, Vascular, and Immune-Contribute to the Cortical Infarcts After Subarachnoid Hemorrhage

The recently published DISCHARGE-1 trial supports the observations of earlier autopsy and neuroimaging studies that almost 70% of all focal brain damage after aneurysmal subarachnoid hemorrhage are anemic infarcts of the cortex, often also affecting the white matter immediately below. The infarcts are not limited by the usual vascular territories. About two-fifths of the ischemic damage occurs within ~ 48 h; the remaining three-fifths are delayed (within ~ 3 weeks). Using neuromonitoring technology in combination with longitudinal neuroimaging, the entire sequence of both early and delayed cortical infarct development after subarachnoid hemorrhage has recently been recorded in patients. Characteristically, cortical infarcts are caused by acute severe vasospastic events, so-called spreading ischemia, triggered by spontaneously occurring spreading depolarization. In locations where a spreading depolarization passes through, cerebral blood flow can drastically drop within a few seconds and remain suppressed for minutes or even hours, often followed by high-amplitude, sustained hyperemia. In spreading depolarization, neurons lead the event, and the other cells of the neurovascular unit (endothelium, vascular smooth muscle, pericytes, astrocytes, microglia, oligodendrocytes) follow. However, dysregulation in cells of all three supersystems-nervous, vascular, and immune-is very likely involved in the dysfunction of the neurovascular unit underlying spreading ischemia. It is assumed that subarachnoid blood, which lies directly on the cortex and enters the parenchyma via glymphatic channels, triggers these dysregulations. This review discusses the neuroglial, neurovascular, and neuroimmunological dysregulations in the context of spreading depolarization and spreading ischemia as critical elements in the pathogenesis of cortical infarcts after subarachnoid hemorrhage.

Similarities in the Electrographic Patterns of Delayed Cerebral Infarction and Brain Death After Aneurysmal and Traumatic Subarachnoid Hemorrhage

While subarachnoid hemorrhage is the second most common hemorrhagic stroke in epidemiologic studies, the recent DISCHARGE-1 trial has shown that in reality, three-quarters of focal brain damage after subarachnoid hemorrhage is ischemic. Two-fifths of these ischemic infarctions occur early and three-fifths are delayed. The vast majority are cortical infarcts whose pathomorphology corresponds to anemic infarcts. Therefore, we propose in this review that subarachnoid hemorrhage as an ischemic-hemorrhagic stroke is rather a third, separate entity in addition to purely ischemic or hemorrhagic strokes. Cumulative focal brain damage, determined by neuroimaging after the first 2 weeks, is the strongest known predictor of patient outcome half a year after the initial hemorrhage. Because of the unique ability to implant neuromonitoring probes at the brain surface before stroke onset and to perform longitudinal MRI scans before and after stroke, delayed cerebral ischemia is currently the stroke variant in humans whose pathophysiological details are by far the best characterized. Optoelectrodes located directly over newly developing delayed infarcts have shown that, as mechanistic correlates of infarct development, spreading depolarizations trigger (1) spreading ischemia, (2) severe hypoxia, (3) persistent activity depression, and (4) transition from clustered spreading depolarizations to a negative ultraslow potential. Furthermore, traumatic brain injury and subarachnoid hemorrhage are the second and third most common etiologies of brain death during continued systemic circulation. Here, we use examples to illustrate that although the pathophysiological cascades associated with brain death are global, they closely resemble the local cascades associated with the development of delayed cerebral infarcts.

The influence of epigenetic biological age on key complications and outcomes in aneurysmal subarachnoid haemorrhage

BACKGROUND

We aimed to investigate the association between DNA-methylation biological age (B-age) calculated as age acceleration (ageAcc) and key aneurysmal subarachnoid haemorrhage (aSAH) complications such as vasospasm, delayed cerebral ischaemia (DCI), poor outcome, and mortality.

METHODS

We conducted a prospective study involving 277 patients with aSAH. B-age was determined in whole blood samples using five epigenetic clocks: Hannum's, Horvath's, Levine's and both versions of Zhang's clocks. Age acceleration was calculated as the residual obtained from regressing out the effect of C-age on the mismatch between C-age and B-age. We then tested the association between ageAcc and vasospasm, DCI and 12-month poor outcome (mRS 3-5) and mortality using linear regression models adjusted for confounders.

RESULTS

Average C-age was 55.0 years, with 66.8% being female. Vasospasm occurred in 143 cases (51.6%), DCI in 70 (25.3%) and poor outcomes in 99 (35.7%), with a mortality rate of 20.6%. Lower ageAcc was linked to vasospasm in Horvath's and Levine's clocks, whereas increased ageAcc was associated with 12-month mortality in Hannum's clock. No significant differences in ageAcc were found for DCI or poor outcome at 12 months with other clocks.

CONCLUSIONS

Our study indicates that B-age is independently associated with vasospasm and 12-month mortality in patients with aSAH. These findings underscore the potential role of epigenetics in understanding the pathophysiology of aSAH-related complications and outcomes.

Decrease in cortical vein opacification predicts outcome after aneurysmal subarachnoid hemorrhage

BACKGROUND

The pathophysiology of brain injury after aneurysmal subarachnoid hemorrhage (aSAH) remains incompletely understood. Cerebral venous flow patterns may be a marker of hemodynamic disruptions after aneurysm rupture. We hypothesized that a decrease in venous filling after aSAH would predict cerebral ischemia and poor outcome.

OBJECTIVE

To examine the hypotheses that venous filling as measured by the cortical venous opacification score (COVES) would (1) decrease after aSAH and (2) that decreased COVES would be associated with higher rates of hydrocephalus, vasospasm, delayed cerebral iscemia (DCI), and poor functional evaluation at outcome.

METHODS

In this retrospective observational cohort study of consecutive patients with aSAH admitted to our tertiary care center between 2016 and 2018, we measured the COVES at admission and at subsequent CT angiography (CTA). We collected clinical variables and compared hydrocephalus, vasospasm, DCI, and outcome at discharge in patients with decrease in COVES with patients with stable COVES.

RESULTS

A total of 22 patients were included in the analysis. COVES decreased from first CTA to second CTA in 11 (50%) patients, by an average of 1.1 points (P=0.01). Patients whose COVES decreased between admission and follow-up imaging were more likely to develop DCI (58% vs 0%, P=0.03) and have a poor outcome at discharge (100% vs 55%, P=0.03) than patients who had no change in COVES. aSAH severity was not associated with initial COVES, and there was no association between change in COVES and development of hydrocephalus or vasospasm.

CONCLUSIONS

Development of decreased venous filling on CTA is associated with poor outcome after aSAH. This association suggests that venous hemodynamics may be reflective of, or contribute to, the pathophysiological mechanisms of brain injury after aSAH. Larger prospective studies are necessary to substantiate our findings.

Pathophysiology, Management, and Therapeutics in Subarachnoid Hemorrhage and Delayed Cerebral Ischemia: An Overview

Subarachnoid hemorrhage (SAH) is a type of hemorrhagic stroke resulting from the rupture of an arterial vessel within the brain. Unlike other stroke types, SAH affects both young adults (mid-40s) and the geriatric population. Patients with SAH often experience significant neurological deficits, leading to a substantial societal burden in terms of lost potential years of life. This review provides a comprehensive overview of SAH, examining its development across different stages (early, intermediate, and late) and highlighting the pathophysiological and pathohistological processes specific to each phase. The clinical management of SAH is also explored, focusing on tailored treatments and interventions to address the unique pathological changes that occur during each stage. Additionally, the paper reviews current treatment modalities and pharmacological interventions based on the evolving guidelines provided by the American Heart Association (AHA). Recent advances in our understanding of SAH will facilitate clinicians' improved management of SAH to reduce the incidence of delayed cerebral ischemia in patients.

Noninvasive and reliable automated detection of spreading depolarization in severe traumatic brain injury using scalp EEG

BACKGROUND

Spreading depolarizations (SDs) are a biomarker and a potentially treatable mechanism of worsening brain injury after traumatic brain injury (TBI). Noninvasive detection of SDs could transform critical care for brain injury patients but has remained elusive. Current methods to detect SDs are based on invasive intracranial recordings with limited spatial coverage. In this study, we establish the feasibility of automated SD detection through noninvasive scalp electroencephalography (EEG) for patients with severe TBI.

METHODS

Building on our recent WAVEFRONT algorithm, we designed an automated SD detection method. This algorithm, with learnable parameters and improved velocity estimation, extracts and tracks propagating power depressions using low-density EEG. The dataset for testing our algorithm contains 700 total SDs in 12 severe TBI patients who underwent decompressive hemicraniectomy (DHC), labeled using ground-truth intracranial EEG recordings. We utilize simultaneously recorded, continuous, low-density (19 electrodes) scalp EEG signals, to quantify the detection accuracy of WAVEFRONT in terms of true positive rate (TPR), false positive rate (FPR), as well as the accuracy of estimating SD frequency.

RESULTS

WAVEFRONT achieves the best average validation accuracy using Delta band EEG: 74% TPR with less than 1.5% FPR. Further, preliminary evidence suggests WAVEFRONT can estimate how frequently SDs may occur.

CONCLUSIONS

We establish the feasibility, and quantify the performance, of noninvasive SD detection after severe TBI using an automated algorithm. The algorithm, WAVEFRONT, can also potentially be used for diagnosis, monitoring, and tailoring treatments for worsening brain injury. Extension of these results to patients with intact skulls requires further study.

Hemodynamic Management in the Prevention and Treatment of Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

One of the most serious complications after subarachnoid hemorrhage (SAH) is delayed cerebral ischemia, the cause of which is multifactorial. Delayed cerebral ischemia considerably worsens neurological outcome and increases the risk of death. The targets of hemodynamic management of SAH have widely changed over the past 30 years. Hypovolemia and hypotension were favored prior to the era of early aneurysmal surgery but were subsequently replaced by the use of hypervolemia and hypertension. More recently, the concept of goal-directed therapy targeting euvolemia, with or without hypertension, is gaining preference. Despite the evolving concepts and the vast literature, fundamental questions related to hemodynamic optimization and its effects on cerebral perfusion and patient outcomes remain unanswered. In this review, we explain the rationale underlying the approaches to hemodynamic management and provide guidance on contemporary strategies related to fluid administration and blood pressure and cardiac output manipulation in the management of SAH.

Cerebrovascular Pressure Reactivity According to Long-Pressure Reactivity Index During Spreading Depolarizations in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Spreading depolarization (SD) has been linked to the impairment of neurovascular coupling. However, the association between SD occurrence and cerebrovascular pressure reactivity as a surrogate of cerebral autoregulation (CA) remains unclear. Therefore, we analyzed CA using the long-pressure reactivity index (L-PRx) during SDs in patients with aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

A retrospective study of patients with aSAH who were recruited at two centers, Heidelberg (HD) and Berlin (BE), was performed. Continuous monitoring of mean arterial pressure (MAP) and intracranial pressure (ICP) was recorded. ICP was measured using an intraparenchymal probe in HD patients and was measure in BE patients through external ventricular drainage. Electrocorticographic (ECoG) activity was continuously recorded between 3 and 13 days after hemorrhage. Autoregulation according to L-PRx was calculated as a moving linear Pearson's correlation of 20-min averages of MAP and ICP. For every identified SD, 60-min intervals of L-PRx were averaged, plotted, and analyzed depending on SD occurrence. Random L-PRx recording periods without SDs served as the control.

RESULTS

A total of 19 patients (HD n = 14, BE n = 5, mean age 50.4 years, 9 female patients) were monitored for a mean duration of 230.4 h (range 96-360, STD ± 69.6 h), during which ECoG recordings revealed a total number of 277 SDs. Of these, 184 represented a single SD, and 93 SDs presented in clusters. In HD patients, mean L-PRx values were 0.12 (95% confidence interval [CI] 0.11-0.13) during SDs and 0.07 (95% CI 0.06-0.08) during control periods (p < 0.001). Similarly, in BE patients, a higher L-PRx value of 0.11 (95% CI 0.11-0.12) was detected during SDs than that during control periods (0.08, 95% CI 0.07-0.09; p < 0.001). In a more detailed analysis, CA changes registered through an intraparenchymal probe (HD patients) revealed that clustered SD periods were characterized by signs of more severely impaired CA (L-PRx during SD in clusters: 0.23 [95% CI 0.20-0.25]; single SD: 0.09 [95% CI 0.08-0.10]; control periods: 0.07 [95% CI 0.06-0.08]; p < 0.001). This group also showed significant increases in ICP during SDs in clusters compared with single SD and control periods.

CONCLUSIONS

Neuromonitoring for simultaneous assessment of cerebrovascular pressure reactivity using 20-min averages of MAP and ICP measured by L-PRx during SD events is feasible. SD occurrence was associated with significant increases in L-PRx values indicative of CA disturbances. An impaired CA was found during SD in clusters when using an intraparenchymal probe. This preliminary study validates the use of cerebrovascular reactivity indices to evaluate CA disturbances during SDs. Our results warrant further investigation in larger prospective patient cohorts.

Cortical Spreading Depolarization and Delayed Cerebral Ischemia; Rethinking Secondary Neurological Injury in Subarachnoid Hemorrhage

Poor outcomes in Subarachnoid Hemorrhage (SAH) are in part due to a unique form of secondary neurological injury known as Delayed Cerebral Ischemia (DCI). DCI is characterized by new neurological insults that continue to occur beyond 72 h after the onset of the hemorrhage. Historically, it was thought to be a consequence of hypoperfusion in the setting of vasospasm. However, DCI was found to occur even in the absence of radiographic evidence of vasospasm. More recent evidence indicates that catastrophic ionic disruptions known as Cortical Spreading Depolarizations (CSD) may be the culprits of DCI. CSDs occur in otherwise healthy brain tissue even without demonstrable vasospasm. Furthermore, CSDs often trigger a complex interplay of neuroinflammation, microthrombi formation, and vasoconstriction. CSDs may therefore represent measurable and modifiable prognostic factors in the prevention and treatment of DCI. Although Ketamine and Nimodipine have shown promise in the treatment and prevention of CSDs in SAH, further research is needed to determine the therapeutic potential of these as well as other agents.

Elevated concentrations of macrophage migration inhibitory factor in serum and cerebral microdialysate are associated with delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Objective

Inflammation is increasingly recognized to be involved in the pathophysiology of aneurysmal subarachnoid hemorrhage (aSAH) and may increase the susceptibility to delayed cerebral ischemia (DCI). Macrophage migration inhibitory factor (MIF) has been shown to be elevated in serum and cerebrospinal fluid (CSF) after aSAH. Here, we determined MIF levels in serum, CSF and cerebral microdialysate (MD) at different time-points after aSAH and evaluated their clinical implications.

Methods

MIF levels were measured in serum, CSF and MD obtained from 30 aSAH patients during early (EP_d1-4), critical (CP_d5-15) and late (LP_d16-21) phase after hemorrhage. For subgroup analyses, patients were stratified based on demographic and clinical data.

Results

MIF levels in serum increased during CP_d5-15 and decreased again during LP_d16-21, while CSF levels showed little changes over time. MD levels peaked during EP_d1-4, decreased during CP_d5-15 and increased again during LP_d16-21. Subgroup analyses revealed significantly higher serum levels in patients with aneurysms located in the anterior vs. posterior circulation during CP_d5-15 (17.3 [15.1-21.1] vs. 10.0 [8.4-11.5] ng/ml, p = 0.009) and in patients with DCI vs. no DCI during CP_d5-15 (17.9 [15.1-22.7] vs. 11.9 [8.9-15.9] ng/ml, p = 0.026) and LP_d16-21 (17.4 [11.7-27.9] vs. 11.3 [9.2-12.2] ng/ml, p = 0.021). In addition, MIF levels in MD during CP_d5-15 were significantly higher in patients with DCI vs. no DCI (3.6 [1.8-10.7] vs. 0.2 [0.1-0.7] ng/ml, p = 0.026), while CSF levels during the whole observation period were similar in all subgroups.

Conclusion

Our findings in a small cohort of aSAH patients provide preliminary data on systemic, global cerebral and local cerebral MIF levels after aSAH and their clinical implications.

Clinical trial registration

ClinicalTrials.gov, identifier: NCT02142166.

Electroencephalogram in the intensive care unit: a focused look at acute brain injury

Over the past decades, electroencephalography (EEG) has become a widely applied and highly sophisticated brain monitoring tool in a variety of intensive care unit (ICU) settings. The most common indication for EEG monitoring currently is the management of refractory status epilepticus. In addition, a number of studies have associated frequent seizures, including nonconvulsive status epilepticus (NCSE), with worsening secondary brain injury and with worse outcomes. With the widespread utilization of EEG (spot and continuous EEG), rhythmic and periodic patterns that do not fulfill strict seizure criteria have been identified, epidemiologically quantified, and linked to pathophysiological events across a wide spectrum of critical and acute illnesses, including acute brain injury. Increasingly, EEG is not just qualitatively described, but also quantitatively analyzed together with other modalities to generate innovative measurements with possible clinical relevance. In this review, we discuss the current knowledge and emerging applications of EEG in the ICU, including seizure detection, ischemia monitoring, detection of cortical spreading depolarizations, assessment of consciousness and prognostication. We also review some technical aspects and challenges of using EEG in the ICU including the logistics of setting up ICU EEG monitoring in resource-limited settings.

Spontaneous subarachnoid haemorrhage

Subarachnoid haemorrhage (SAH) is the third most common subtype of stroke. Incidence has decreased over past decades, possibly in part related to lifestyle changes such as smoking cessation and management of hypertension. Approximately a quarter of patients with SAH die before hospital admission; overall outcomes are improved in those admitted to hospital, but with elevated risk of long-term neuropsychiatric sequelae such as depression. The disease continues to have a major public health impact as the mean age of onset is in the mid-fifties, leading to many years of reduced quality of life. The clinical presentation varies, but severe, sudden onset of headache is the most common symptom, variably associated with meningismus, transient or prolonged unconsciousness, and focal neurological deficits including cranial nerve palsies and paresis. Diagnosis is made by CT scan of the head possibly followed by lumbar puncture. Aneurysms are commonly the underlying vascular cause of spontaneous SAH and are diagnosed by angiography. Emergent therapeutic interventions are focused on decreasing the risk of rebleeding (ie, preventing hypertension and correcting coagulopathies) and, most crucially, early aneurysm treatment using coil embolisation or clipping. Management of the disease is best delivered in specialised intensive care units and high-volume centres by a multidisciplinary team. Increasingly, early brain injury presenting as global cerebral oedema is recognised as a potential treatment target but, currently, disease management is largely focused on addressing secondary complications such as hydrocephalus, delayed cerebral ischaemia related to microvascular dysfunction and large vessel vasospasm, and medical complications such as stunned myocardium and hospital acquired infections.

High epileptiform discharge burden predicts delayed cerebral ischemia after subarachnoid hemorrhage

OBJECTIVE

To investigate whether epileptiform discharge burden can identify those at risk for delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH).

METHODS

Retrospective analysis of 113 moderate to severe grade SAH patients who had continuous EEG (cEEG) recordings during their hospitalization. We calculated the burden of epileptiform discharges (ED), measured as number of ED per hour.

RESULTS

We find that many SAH patients have an increase in ED burden during the first 3-10 days following rupture, the major risk period for DCI. However, those who develop DCI have a significantly higher hourly burden from days 3.5-6 after SAH vs. those who do not. ED burden is higher in DCI patients when assessed in relation to the onset of DCI (area under the receiver operator curve 0.72). Finally, specific trends of ED burden over time, assessed by group-based trajectory analysis, also help stratify DCI risk.

CONCLUSIONS

These results suggest that ED burden is a useful parameter for identifying those at higher risk of developing DCI after SAH. The higher burden rate associated with DCI supports the theory of metabolic supply-demand mismatch which contributes to this complication.

SIGNIFICANCE

ED burden is a novel biomarker for predicting those at high risk of DCI.

Cerebral Autoregulation Correlation With Outcomes and Spreading Depolarization in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Delayed cerebral ischemia remains one of the principal therapeutic targets after aneurysmal subarachnoid hemorrhage. While large vessel vasospasm may contribute to ischemia, increasing evidence suggests that physiological impairment through disrupted impaired cerebral autoregulation (CA) and spreading depolarizations (SDs) also contribute to delayed cerebral ischemia and poor neurological outcome. This study seeks to explore the intermeasure correlation of different measures of CA, as well as correlation with SD and neurological outcome.

METHODS

Simultaneous measurement of 7 continuous indices of CA was calculated in 19 subjects entered in a prospective study of SD in aneurysmal subarachnoid hemorrhage undergoing surgical aneurysm clipping. Intermeasure agreement was assessed, and the association of each index with modified Rankin Scale score at 90 days and occurrence of SD was assessed.

RESULTS

There were 4102 hours of total monitoring time across the 19 subjects. In time-resolved assessment, no CA measures demonstrated significant correlation; however, most demonstrate significant correlation averaged over 1 hour. Pressure reactivity (PRx), oxygen reactivity, and oxygen saturation reactivity were significantly correlated with modified Rankin Scale score at 90 days. PRx and oxygen reactivity also were correlated with the occurrence of SD events. Across multiple CA measure reactivity indices, a threshold between 0.3 and 0.5 was most associated with intervals containing SD.

CONCLUSIONS

Different continuous CA indices do not correlate well with each other on a highly time-resolved basis, so should not be viewed as interchangeable. PRx and oxygen reactivity are the most reliable indices in identifying risk of worse outcome in patients with aneurysmal subarachnoid hemorrhage undergoing surgical treatment. SD occurrence is correlated with impaired CA across multiple CA measurement techniques and may represent the pathological mechanism of delayed cerebral ischemia in patients with impaired CA. Optimization of CA in patients with aneurysmal subarachnoid hemorrhage may lead to decreased incidence of SD and improved neurological outcomes. Future studies are needed to evaluate these hypotheses and approaches.

Cortical Spreading Depolarizations and Clinically Measured Scalp EEG Activity After Aneurysmal Subarachnoid Hemorrhage and Traumatic Brain Injury

BACKGROUND

Spreading depolarizations (SDs) are associated with worse outcome following subarachnoid hemorrhage (SAH) and traumatic brain injury (TBI), but gold standard detection requires electrocorticography with a subdural strip electrode. Electroencephalography (EEG) ictal-interictal continuum abnormalities are associated with poor outcomes after TBI and with both delayed cerebral ischemia (DCI) and poor outcomes after SAH. We examined rates of SD detection in patients with SAH and TBI with intraparenchymal and subdural strip electrodes and assessed which continuous EEG (cEEG) measures were associated with intracranially quantified SDs.

METHODS

In this single-center cohort, we included patients with SAH and TBI undergoing ≥ 24 h of interpretable intracranial monitoring via eight-contact intraparenchymal or six-contact subdural strip platinum electrodes or both. SDs were rated according to established consensus criteria and compared with cEEG findings rated according to the American Clinical Neurophysiology Society critical care EEG monitoring consensus criteria: lateralized rhythmic delta activity, generalized rhythmic delta activity, lateralized periodic discharges, generalized periodic discharges, any ictal-interictal continuum, or a composite scalp EEG tool for seizure risk estimation: the 2HELPS2B score. Among patients with SAH, cEEG was assessed for validated DCI biomarkers: new or worsening epileptiform abnormalities and new background deterioration.

RESULTS

Over 6 years, SDs were recorded in 5 (18%) of 28 patients recorded with intraparenchymal electrodes and 4 (40%) of 10 patients recorded with subdural strip electrodes. There was no significant association between occurrence of SDs and day 1 cEEG findings (American Clinical Neurophysiology Society main terms lateralized periodic discharges, generalized periodic discharges, lateralized rhythmic delta activity, or seizures, individually or in combination). After SAH, established cEEG DCI predictors were not associated with SDs.

CONCLUSIONS

Intraparenchymal recordings yielded low rates of SD, and documented SDs were not associated with ictal-interictal continuum abnormalities or other cEEG DCI predictors. Identifying scalp EEG correlates of SD may require training computational EEG analytics and use of gold standard subdural strip electrocorticography recordings.

Case report: Delayed posttraumatic cortical laminar necrosis secondary to spreading depolarization induced spreading ischemia from old subarachnoid hemorrhage

Cortical laminar necrosis usually occurs secondary to infarcts or hypoxia, however other causes, including hypoglycemia, status epilepticus and immunosuppressive therapy have been reported. To our knowledge, CLN is not a phenomenon expected in the case of trauma. We report a unique case of delayed post-traumatic CLN which occurred 30 days after the initial trauma, without any proven cause apart from possible spreading depolarization induced spreading ischemia from adjacent subarachnoid hemorrhage with distinct radiologic features.

Spreading depolarizations in ischaemia after subarachnoid haemorrhage, a diagnostic phase III study

Focal brain damage after aneurysmal subarachnoid haemorrhage predominantly results from intracerebral haemorrhage, and early and delayed cerebral ischaemia. The prospective, observational, multicentre, cohort, diagnostic phase III trial, DISCHARGE-1, primarily investigated whether the peak total spreading depolarization-induced depression duration of a recording day during delayed neuromonitoring (delayed depression duration) indicates delayed ipsilateral infarction. Consecutive patients (n = 205) who required neurosurgery were enrolled in six university hospitals from September 2009 to April 2018. Subdural electrodes for electrocorticography were implanted. Participants were excluded on the basis of exclusion criteria, technical problems in data quality, missing neuroimages or patient withdrawal (n = 25). Evaluators were blinded to other measures. Longitudinal MRI, and CT studies if clinically indicated, revealed that 162/180 patients developed focal brain damage during the first 2 weeks. During 4.5 years of cumulative recording, 6777 spreading depolarizations occurred in 161/180 patients and 238 electrographic seizures in 14/180. Ten patients died early; 90/170 developed delayed infarction ipsilateral to the electrodes. Primary objective was to investigate whether a 60-min delayed depression duration cut-off in a 24-h window predicts delayed infarction with >0.60 sensitivity and >0.80 specificity, and to estimate a new cut-off. The 60-min cut-off was too short. Sensitivity was sufficient [= 0.76 (95% confidence interval: 0.65-0.84), P = 0.0014] but specificity was 0.59 (0.47-0.70), i.e. <0.80 (P < 0.0001). Nevertheless, the area under the receiver operating characteristic (AUROC) curve of delayed depression duration was 0.76 (0.69-0.83, P < 0.0001) for delayed infarction and 0.88 (0.81-0.94, P < 0.0001) for delayed ischaemia (reversible delayed neurological deficit or infarction). In secondary analysis, a new 180-min cut-off indicated delayed infarction with a targeted 0.62 sensitivity and 0.83 specificity. In awake patients, the AUROC curve of delayed depression duration was 0.84 (0.70-0.97, P = 0.001) and the prespecified 60-min cut-off showed 0.71 sensitivity and 0.82 specificity for reversible neurological deficits. In multivariate analysis, delayed depression duration (β = 0.474, P < 0.001), delayed median Glasgow Coma Score (β = -0.201, P = 0.005) and peak transcranial Doppler (β = 0.169, P = 0.016) explained 35% of variance in delayed infarction. Another key finding was that spreading depolarization-variables were included in every multiple regression model of early, delayed and total brain damage, patient outcome and death, strongly suggesting that they are an independent biomarker of progressive brain injury. While the 60-min cut-off of cumulative depression in a 24-h window indicated reversible delayed neurological deficit, only a 180-min cut-off indicated new infarction with >0.60 sensitivity and >0.80 specificity. Although spontaneous resolution of the neurological deficit is still possible, we recommend initiating rescue treatment at the 60-min rather than the 180-min cut-off if progression of injury to infarction is to be prevented.

Role of Dexmedetomidine in Aneurysmal Subarachnoid Hemorrhage: A Comprehensive Scoping Review

Dexmedetomidine (DEX), an α2-adrenergic agonist, has been widely used for anesthesia, pain control, and intensive care unit sedation. Besides sleep-like sedation, DEX has many other beneficial effects, such as anti-inflammation, antioxidation, and anticell death. Subarachnoid hemorrhage (SAH), a severe and potentially fatal form of stroke, is a complex disease that is divided into 2 phases: early brain injury and delayed cerebral ischemia. In each phase, several pathologic changes are involved, including disturbed intracranial homeostasis, metabolic failure, blood-brain barrier damage, vasospasm, microthrombosis, and cortical spreading depolarization. DEX has been shown to have an effect on these SAH-related pathologic processes. Research shows that DEX could serve as a protective therapy for patients with SAH due to its ability to maintain stable intracerebral homeostasis, balance coagulation-fibrinolysis, repair a damaged blood-brain barrier as well as prevent vasospasm and suppress cortical spreading depolarization by anti-inflammatory, antioxidative, antiapoptotic, and vasoconstriction-dilation effects. In this scoping review, we critically assess the existing data on the potential protective effect of DEX after SAH. So far, only 1 retrospective clinical trial assessing the effect of DEX on clinical outcomes after SAH has been performed. Hence, more trials are still needed as well as translational research bringing results from bench to bedside.

The Role of Soluble Urokinase Plasminogen Activator Receptor (suPAR) in the Context of Aneurysmal Subarachnoid Hemorrhage (aSAH)—A Prospective Observational Study

Objective

Outcome after aneurysmal subarachnoid hemorrhage (aSAH) is highly variable and largely determined by early brain injury and delayed cerebral ischemia (DCI). Soluble urokinase plasminogen activator receptor (suPAR) represents a promising inflammatory marker which has previously been associated with outcome in traumatic brain injury and stroke patients. However, its relevance in the context of inflammatory changes after aSAH is unclear. Here, we aimed to characterize the role of circulating suPAR in both serum and cerebrospinal fluid (CSF) as a novel biomarker for aSAH patients.

Methods

A total of 36 aSAH patients, 10 control patients with unruptured abdominal aneurysm and 32 healthy volunteers were included for analysis. suPAR was analyzed on the day of admission in all patients. In aSAH patients, suPAR was also determined on the day of DCI and the respective time frame in asymptomatic patients. One- and two-sample t-tests were used for simple difference comparisons within and between groups. Regression analysis was used to assess the influence of suPAR levels on outcome in terms of modified Rankin score.

Results

Significantly elevated suPAR serum levels (suPAR-SL) on admission were found for aSAH patients compared to healthy controls, but not compared to vascular control patients. Disease severity as documented according to Hunt and Hess grade and modified Fisher grade was associated with higher suPAR CSF levels (suPAR-CSFL). In aSAH patients, suPAR-SL increased daily by 4%, while suPAR-CSFL showed a significantly faster daily increase by an average of 22.5% per day. Each increase of the suPAR-SL by 1 ng/ml more than tripled the odds of developing DCI (OR = 3.06). While admission suPAR-CSFL was not predictive of DCI, we observed a significant correlation with modified Rankin's degree of disability at discharge.

Conclusion

Elevated suPAR serum level on admission as a biomarker for early inflammation after aSAH is associated with an increased risk of DCI. Elevated suPAR-CSFL levels correlate with a higher degree of disability at discharge. These distinct relations and the observation of a continuous increase over time affirm the role of inflammation in aSAH and require further study.

The Utility of Quantitative EEG in Detecting Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

SUMMARY

In this review, we discuss the utility of quantitative EEG parameters for the detection of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage in the context of the complex pathophysiology of DCI and the limitations of current diagnostic methods. Because of the multifactorial pathophysiology of DCI, methodologies solely assessing blood vessel narrowing (vasospasm) are insufficient to detect all DCI. Quantitative EEG has facilitated the exploration of EEG as a diagnostic modality of DCI. Multiple quantitative EEG parameters such as alpha power, relative alpha variability, and alpha/delta ratio show reliable detection of DCI in multiple studies. Recent studies on epileptiform abnormalities suggest that their potential for the detection of DCI. Quantitative EEG is a promising, continuous, noninvasive, monitoring modality of DCI implementable in daily practice. Future work should validate these parameters in larger populations, facilitated by the development of automated detection algorithms and multimodal data integration.

Early Detection of Cerebral Herniation by Continuous Electroencephalography and Quantitative Analysis

Continuous electroencephalography (cEEG) and quantitative analysis of EEG (qEEG) are used in various circumstances such as detecting seizures, identifying acute or delayed cerebral ischemia, monitoring sedative therapy, or assessing prognosis. The authors report 2 cases: (1) Case #1 was a patient with unilateral cerebral edema and uncal herniation with asymmetric cEEG and qEEG changes detected an hour before clinical examination changes were noted and (2) Case #2 was a patient with diffuse cerebral edema and trans-tentorial herniation with symmetric cEEG and qEEG changes detected an hour before clinical examination changes were noted. These cases demonstrate the ability of cEEG and qEEG in early detection of different types of cerebral herniation. qEEG can be utilized by intensive care unit (ICU) staff not trained in EEG interpretation as a surveillance method to detect cerebral herniation, which may provide an opportunity for early intervention in high-risk patients.

Inhaled Nitric Oxide Treatment for Aneurysmal SAH Patients With Delayed Cerebral Ischemia

Background

We demonstrated experimentally that inhaled nitric oxide (iNO) dilates hypoperfused arterioles, increases tissue perfusion, and improves neurological outcome following subarachnoid hemorrhage (SAH) in mice. We performed a prospective pilot study to evaluate iNO in patients with delayed cerebral ischemia after SAH.

Methods

SAH patients with delayed cerebral ischemia and hypoperfusion despite conservative treatment were included. iNO was administered at a maximum dose of 40 ppm. The response to iNO was considered positive if: cerebral artery diameter increased by 10% in digital subtraction angiography (DSA), or tissue oxygen partial pressure (PtiO₂) increased by > 5 mmHg, or transcranial doppler (TCD) values decreased more than 30 cm/sec, or mean transit time (MTT) decreased below 6.5 secs in CT perfusion (CTP). Patient outcome was assessed at 6 months with the modified Rankin Scale (mRS).

Results

Seven patients were enrolled between February 2013 and September 2016. Median duration of iNO administration was 23 h. The primary endpoint was reached in all patients (five out of 17 DSA examinations, 19 out of 29 PtiO₂ time points, nine out of 26 TCD examinations, three out of five CTP examinations). No adverse events necessitating the cessation of iNO were observed. At 6 months, three patients presented with a mRS score of 0, one patient each with an mRS score of 2 and 3, and two patients had died.

Conclusion

Administration of iNO in SAH patients is safe. These results call for a larger prospective evaluation.

Cortical Spreading Depolarizations in Aneurysmal Subarachnoid Hemorrhage: An Overview of Current Knowledge and Future Perspectives

Despite significant advances in the management of aneurysmal subarachnoid hemorrhage (SAH), morbidity and mortality remain devastating particularly for high-grade SAH. Poor functional outcome usually results from delayed cerebral ischemia (DCI). The pathogenesis of DCI during aneurysmal SAH has historically been attributed to cerebral vasospasm, but spreading depolarizations (SDs) are now considered to play a central role in DCI. During SAH, SDs may produce an inverse hemodynamic response leading to spreading ischemia. Several animal models have contributed to a better understanding of the pathogenesis of SDs during aneurysmal SAH and provided new therapeutic approaches including N-methyl-D-aspartate receptor antagonists and phosphodiesterase inhibitors. Herein we review the current knowledge in the field of SDs' pathogenesis and we detail the key experimental and clinical studies that have opened interesting new therapeutic approaches to prevent DCI in aneurysmal SAH.

Predictive effects of admission white blood cell counts and hounsfield unit values on delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

OBJECTIVE

Neuroinflammatory response is deemed the primary pathogenesis of delayed cerebral ischemia (DCI) caused by aneurysmal subarachnoid hemorrhage (aSAH). Both white blood cell (WBC) count and Hounsfield Unit (HU) are gradually considered can reflect inflammation in DCI. This study aims to identify the relationship between WBC count and HU value and investigate the effects of both indicators in predicting DCI after aSAH.

METHODS

We enrolled 109 patients with aSAH admitted within 24 h of onset in our study. A multivariate logistic regression analysis was used to evaluate the admission WBC count, HU value, and combined WBC-HU associated with DCI. The receiver operating characteristic curve and area under the curve (AUC) were used to determine thresholds and detect the predictive ability of these predictors. These indicators were also compared with the established inflammation markers.

RESULTS

Thirty-six (33%) patients developed DCI. Both WBC count and HU value were strongly associated with the admission glucose level (ρ = .303, p = .001; ρ = .273, p = .004), World Federation of Neurosurgical Societies grade (ρ = .452, p < .001; ρ = .578; p < .001), Hunt-Hess grade (ρ = .450, p < .001; ρ = .510, p < .001), and modified Fisher scale score (ρ = .357, p < .001; ρ = .330, p < .001). After controlling these public variables, WBC count (ρ = .300, p = .002) positively correlated with HU value. An early elevated WBC (odds ratio [OR] 1.449, 95% confidence interval [CI]: 1.183-1.774, p < .001) count and HU value (OR 1.304, 95%CI: 1.149-1.479, p < .001) could independently predict the occurrence of DCI. However, only these patients with both WBC count and HU value exceeding the cut-off points (OR 36.89, 95%CI: 5.606-242.78, p < .001) were strongly correlated with DCI. Compared with a single WBC count (AUC 0.811, 95%CI: 0.729-0.892, p < .001) or HU value (AUC 0.869, 95%CI: 0.803-0.936, p < .001), the combined WBC-HU (AUC 0.898, 95%CI: 0.839-0.957, p < .001) demonstrated a better ability to predict the occurrence of DCI. Inspiringly, the prediction performance of these indicators outperformed the established inflammatory markers.

CONCLUSION

An early elevated WBC count and HU value could independently predict DCI occurrence between 4 and 30 days after aSAH. Furthermore, WBC count was positively correlated with HU value, and the combined WBC-HU demonstrated a superior prediction ability for DCI development compared with the individual indicator.

The Role of the Glycocalyx in the Pathophysiology of Subarachnoid Hemorrhage-Induced Delayed Cerebral Ischemia

The glycocalyx is an important constituent of blood vessels located between the bloodstream and the endothelium. It plays a pivotal role in intercellular interactions in neuroinflammation, reduction of vascular oxidative stress, and provides a barrier regulating vascular permeability. In the brain, the glycocalyx is closely related to functions of the blood-brain barrier and neurovascular unit, both responsible for adequate neurovascular responses to potential threats to cerebral homeostasis. An aneurysmal subarachnoid hemorrhage (aSAH) occurs following rupture of an intracranial aneurysm and leads to immediate brain damage (early brain injury). In some cases, this can result in secondary brain damage, also known as delayed cerebral ischemia (DCI). DCI is a life-threatening condition that affects up to 30% of all aSAH patients. As such, it is associated with substantial societal and healthcare-related costs. Causes of DCI are multifactorial and thought to involve neuroinflammation, oxidative stress, neuroinflammation, thrombosis, and neurovascular uncoupling. To date, prediction of DCI is limited, and preventive and effective treatment strategies of DCI are scarce. There is increasing evidence that the glycocalyx is disrupted following an aSAH, and that glycocalyx disruption could precipitate or aggravate DCI. This review explores the potential role of the glycocalyx in the pathophysiological mechanisms contributing to DCI following aSAH. Understanding the role of the glycocalyx in DCI could advance the development of improved methods to predict DCI or identify patients at risk for DCI. This knowledge may also alter the methods and timing of preventive and treatment strategies of DCI. To this end, we review the potential and limitations of methods currently used to evaluate the glycocalyx, and strategies to restore or prevent glycocalyx shedding.

Local Application of Magnesium Sulfate Solution Suppressed Cortical Spreading Ischemia and Reduced Brain Damage in a Rat Subarachnoid Hemorrhage-Mimicking Model

OBJECTIVE

Cortical spreading depolarization (CSD), cortical spreading ischemia (CSI), and early brain injury are involved in the occurrence of delayed brain ischemia after subarachnoid hemorrhage (SAH). We tested whether local application of magnesium (Mg) sulfate solution suppressed CSD and CSI, and decreased brain damage in a rat SAH-mimicking model.

METHODS

Nitric oxide synthase inhibitor L-NG-nitroarginine methyl ester (L-NAME) and high concentration potassium solution were topically applied to simulate the environment after SAH. We irrigated the parietal cortex with artificial cerebrospinal fluid (ACSF), containing L-NAME (1 mM), K⁺ (35 mM), and Mg²⁺ (5 mM). Forty-five rats were divided into 3 groups: sham surgery (sham group), L-NAME + [K⁺]_ACSF (control group), and L-NAME + [K⁺]_ACSF + [Mg²⁺] (Mg group). CSD was induced by topical application with 1 M KCl solution in 3 groups. The effects of Mg administration on CSD and cerebral blood flow were evaluated. Histological brain tissue damage, body weight, and neurological score were assessed at 2 days after insult.

RESULTS

Mg solution significantly shortened the total depolarization time, and reduced CSI, histological brain damage, and brain edema compared with those of the control group (P < 0.05). Body weight loss was significantly suppressed in the Mg group (P < 0.05), but neurological score did not improve.

CONCLUSIONS

Local application of Mg suppressed CSI and reduced brain damage in a rat SAH-mimicking model. Mg irrigation therapy may be beneficial to suppress brain damage due to CSI after SAH.

Association Between Spreading Depolarization and Delayed Cerebral Ischemia After Subarachnoid Hemorrhage: Post Hoc Analysis of a Randomized Trial of the Effect of Cilostazol on Delayed Cerebral Ischemia

BACKGROUND

Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH) remains an important problem with a complex pathophysiology. We used data from a single-center randomized trial to assess the effect of a phosphodiesterase inhibitor, cilostazol, in patients with aneurysmal SAH to explore the relationships of DCI with vasospasm, spreading depolarization (SD) and microcirculatory disturbance.

METHODS

A post hoc analysis of a single-center, prospective, randomized trial of the effect of cilostazol on DCI and SD after aneurysmal SAH was performed. From all randomized cohorts, patients who underwent both SD monitoring and digital subtraction angiography (DSA) on day 9 ± 2 from onset were included. Cerebral circulation time (CCT), which was divided into proximal CCT and peripheral CCT (as a measure of microcirculatory disturbance), was obtained from DSA. Logistic regression was conducted to determine factors associated with DCI.

RESULTS

Complete data were available for 28 of 50 patients. Of the 28 patients, 8 (28.5%) had DCI during the study period. Multivariate analysis indicated a strong association between the number of SDs on the day DSA was performed (i.e., a delayed time point after SAH onset) and DCI (odds ratio 2.064, 95% confidence interval 1.045-4.075, P = 0.037, area under the curve 0.836), whereas the degree of angiographic vasospasm and peripheral CCT were not significant factors for DCI.

CONCLUSIONS

There is a strong association between SD and DCI. Our results suggest that SD is an important therapeutic target and a potentially useful biomarker for DCI.

Delayed Cerebral Ischemia after Subarachnoid Hemorrhage

Delayed cerebral ischemia (DCI) is the most feared complication of aneurysmal subarachnoid hemorrhage (aSAH). It increases the mortality and morbidity associated with aSAH. Previously, large cerebral artery vasospasm was thought to be the sole major contributing factor associated with increased risk of DCI. Recent literature has challenged this concept. We conducted a literature search using PUBMED as the prime source of articles discussing various other factors which may contribute to the development of DCI both in the presence or absence of large cerebral artery vasospasm. These factors include microvascular spasm, micro-thrombosis, cerebrovascular dysregulation, and cortical spreading depolarization. These factors collectively result in inflammation of brain parenchyma, which is thought to precipitate early brain injury and DCI. We conclude that diagnostic modalities need to be refined in order to diagnose DCI more efficiently in its early phase, and newer interventions need to be developed to prevent and treat this condition. These newer interventions are currently being studied in experimental models. However, their effectiveness on patients with aSAH is yet to be determined.

Pathophysiology of Delayed Cerebral Ischemia After Subarachnoid Hemorrhage: A Review

Delayed cerebral ischemia is a major predictor of poor outcomes in patients who suffer subarachnoid hemorrhage. Treatment options are limited and often ineffective despite many years of investigation and clinical trials. Modern advances in basic science have produced a much more complex, multifactorial framework in which delayed cerebral ischemia is better understood and novel treatments can be developed. Leveraging this knowledge to improve outcomes, however, depends on a holistic understanding of the disease process. We conducted a review of the literature to analyze the current state of investigation into delayed cerebral ischemia with emphasis on the major themes that have emerged over the past decades. Specifically, we discuss microcirculatory dysfunction, glymphatic impairment, inflammation, and neuroelectric disruption as pathological factors in addition to the canonical focus on cerebral vasospasm. This review intends to give clinicians and researchers a summary of the foundations of delayed cerebral ischemia pathophysiology while also underscoring the interactions and interdependencies between pathological factors. Through this overview, we also highlight the advances in translational studies and potential future therapeutic opportunities.

Role of endothelial nitric oxide synthase for early brain injury after subarachnoid hemorrhage in mice

The first few hours and days after subarachnoid hemorrhage (SAH) are characterized by cerebral ischemia, spasms of pial arterioles, and a significant reduction of cerebral microperfusion, however, the mechanisms of this early microcirculatory dysfunction are still unknown. Endothelial nitric oxide production is reduced after SAH and exogenous application of NO reduces post-hemorrhagic microvasospasm. Therefore, we hypothesize that the endothelial NO-synthase (eNOS) may be involved in the formation of microvasospasms, microcirculatory dysfunction, and unfavorable outcome after SAH. SAH was induced in male eNOS deficient (eNOS^-/-) mice by endovascular MCA perforation. Three hours later, the cerebral microcirculation was visualized using in vivo 2-photon-microscopy. eNOS^-/- mice had more severe SAHs, more severe ischemia, three time more rebleedings, and a massively increased mortality (50 vs. 0%) as compared to wild type (WT) littermate controls. Three hours after SAH eNOS^-/- mice had fewer perfused microvessels and 40% more microvasospasms than WT mice. The current study indicates that a proper function of eNOS plays a key role for a favorable outcome after SAH and helps to explain why patients suffering from hypertension or other conditions associated with impaired eNOS function, have a higher risk of unfavorable outcome after SAH.

Nitric Oxide-Based Treatment of Poor-Grade Patients After Severe Aneurysmal Subarachnoid Hemorrhage

Background

Patients with aneurysmal subarachnoid hemorrhage (aSAH) require close treatment in neuro intensive care units (NICUs). The treatments available to counteract secondary deterioration and delayed ischemic events remain restricted; moreover, available neuro-monitoring of comatose patients is undependable. In comatose patients, clinical signs are hidden, and timing interventions to prevent the evolution of a perfusion disorder in response to fixed ischemic brain damage remain a challenge for NICU teams. Consequently, comatose patients often suffer secondary brain infarctions. The outcomes for long-term intubated patients w/wo pupil dilatation are the worst, with only 10% surviving. We previously added two nitroxide (NO) donors to the standard treatment: continuous intravenous administration of Molsidomine in patients with mild-to-moderate aSAH and, if required as a supplement, intraventricular boluses of sodium nitroprusside (SNP) in high-risk patients to overcome the so-called NO-sink effect, which leads to vasospasm and perfusion disorders. NO boluses were guided by clinical status and promptly reversed recurrent episodes of delayed ischemic neurological deficit. In this study, we tried to translate this concept, the initiation of intraventricular NO application on top of continuous Molsidomine infusion, from awake to comatose patients who lack neurological–clinical monitoring but are primarily monitored using frequently applied transcranial Doppler (TCD).

Methods

In this observational, retrospective, nonrandomized feasibility study, 18 consecutive aSAH comatose/intubated patients (Hunt and Hess IV/V with/without pupil dilatation) whose poor clinical status precluded clinical monitoring received standard neuro-intensive care, frequent TCD monitoring, continuous intravenous Molsidomine plus intraventricular SNP boluses after TCD-confirmed macrospasm during the daytime and on a fixed nighttime schedule.

Results

Very likely associated with the application of SNP, which is a matter of further investigation, vasospasm-related TCD findings promptly and reliably reversed or substantially weakened (p < 0.0001) afterward. Delayed cerebral ischemia (DCI) occurred only during loose, low-dose or interrupted treatment (17% vs. an estimated 65% with secondary infarctions) in 17 responders. However, despite their worse initial condition, 29.4% of the responders survived (expected 10%) and four achieved Glasgow Outcome Scale Extended (GOSE) 8–6, modified Rankin Scale (mRS) 0–1 or National Institutes of Health Stroke Scale (NIHSS) 0–2.

Conclusions

Even in comatose/intubated patients, TCD-guided dual-compartment administration of NO donors probably could reverse macrospasm and seems to be feasible. The number of DCI was much lower than expected in this specific subgroup, indicating that this treatment possibly provides a positive impact on outcomes. A randomized trial should verify or falsify our results.

Urea-Creatinine Ratio (UCR) After Aneurysmal Subarachnoid Hemorrhage: Association of Protein Catabolism with Complication Rate and Outcome

OBJECTIVE

The urea-creatinine ratio (UCR) has been proposed as potential biomarker for critical illness-associated catabolism. Its role in the context of aneurysmal subarachnoid hemorrhage (aSAH) remains to be elucidated, which was the aim of the present study.

METHODS

We enrolled 66 patients with aSAH with normal renal function and 36 patients undergoing elective cardiac surgery as a control group for the effects of surgery. In patients with aSAH, the predictive or diagnostic value of early (day 0-2) and critical (day 5-7) UCRs was assessed with regard to delayed cerebral ischemia (DCI), DCI-related infarction, and clinical outcome after 12 months.

RESULTS

Preoperatively, UCR was similar both groups. Within 2 days postoperatively, UCRs increased significantly in patients in the elective cardiac surgery group (P < 0.001) but decreased back to baseline on day 5-7 (P = 0.245), whereas UCRs in patients with aSAH increased to significantly greater levels on day 5-7 (P = 0.028). Greater early or critical UCRs were associated with poor clinical outcomes (P = 0.015) or DCI (P = 0.011), DCI-related infarction (P = 0.006), and poor clinical outcomes (P < 0.001) respectively. In multivariate analysis, there was an independent association between greater early UCRs and poor clinical outcomes (P = 0.026).

CONCLUSIONS

In this exploratory study of UCR in the context of aSAH, greater early values were predictive for a poor clinical outcome after 12 months, whereas greater critical values were associated with DCI, DCI-related infarctions, and poor clinical outcomes. The clinical implications as well as the pathophysiologic relevance of protein catabolism should be explored further in the context of aSAH.

Cerebral aneurysms and cervical artery dissection: Neurological complications and genetic associations

Dissections and aneurysms are two of the more common nonatherosclerotic arteriopathies of the cerebrovascular system and a significant contributor to neurovascular complications, particularly in the young. Specifically, ruptured intracranial aneurysms (IA) account for nearly 500,000 cases of subarachnoid hemorrhage annually with a 30-day mortality approaching 40% and survivors suffering often permanent neurologic deficits and disability. Unruptured IAs require dedicated assessment of risk and often warrant serial radiologic monitoring. Cervical artery dissection, affecting the carotid and vertebral arteries, accounts for nearly 20% of strokes in young and middle-aged adults. While approximately 70% of cervical artery dissection (CeAD) cases present with stroke or TIA, additional neurologic complications include severe headache and neck pain, oculosympathetic defect (i.e., partial Horner's syndrome), acute vestibular syndrome, and rarely lower cranial nerve palsies. Both aneurysms and dissections of the cerebrovascular system may occur frequently in patients with syndromic connective tissue disorders; however, the majority of cases are spontaneously occurring or mildly heritable with both polygenic and environmental associations. Fibromuscular dysplasia, in particular, is commonly associated with both risk of CeAD and IA formation. Further research is needed to better understand the pathophysiology of both IA and CeAD to better understand risk, improve treatments, and prevent devastating neurologic complications.

Electroencephalography, Hospital Complications, and Longitudinal Outcomes After Subarachnoid Hemorrhage

BACKGROUND

Following non-traumatic subarachnoid hemorrhage (SAH), in-hospital delayed cerebral ischemia is predicted by two chief events on continuous EEG (cEEG): new or worsening epileptiform abnormalities (EAs) and deterioration of cEEG background frequencies. We evaluated the association between longitudinal outcomes and these cEEG biomarkers. We additionally evaluated the association between longitudinal outcomes and other in-hospital complications.

METHODS

Patients with nontraumatic SAH undergoing ≥ 3 days of cEEG monitoring were enrolled in a prospective study evaluating longitudinal outcomes. Modified Rankin Scale (mRS) was assessed at discharge, and at 3- and 6-month follow-up time points. Adjusting for baseline severity in a cumulative proportional odds model, we modeled the mRS ordinally and measured the association between mRS and two forms of in-hospital cEEG deterioration: (1) cEEG evidence of new or worsening epileptiform abnormalities and (2) cEEG evidence of new background deterioration. We compared the magnitude of these associations at each time point with the association between mRS and other in-hospital complications: (1) delayed cerebral ischemia (DCI), (2) hospital-acquired infections (HAI), and (3) hydrocephalus. In a secondary analysis, we employed a linear mixed effects model to examine the association of mRS over time (dichotomized as 0-3 vs. 4-6) with both biomarkers of cEEG deterioration and with other in-hospital complications.

RESULTS

In total, 175 mRS assessments were performed in 59 patients. New or worsening EAs developed in 23 (39%) patients, and new background deterioration developed in 24 (41%). Among cEEG biomarkers, new or worsening EAs were independently associated with mRS at discharge, 3, and 6 months, respectively (adjusted cumulative proportional odds 4.99, 95% CI 1.60-15.6; 3.28, 95% CI 1.14-9.5; and 2.71, 95% CI 0.95-7.76), but cEEG background deterioration lacked an association. Among hospital complications, DCI was associated with discharge, 3-, and 6-month outcomes (adjusted cumulative proportional odds 4.75, 95% CI 1.64-13.8; 3.4; 95% CI 1.24-9.01; and 2.45, 95% CI 0.94-6.6), but HAI and hydrocephalus lacked an association. The mixed effects model demonstrated that these associations were sustained over longitudinal assessments without an interaction with time.

CONCLUSION

Although new or worsening EAs and cEEG background deterioration have both been shown to predict DCI, only new or worsening EAs are associated with a sustained impairment in functional outcome. This novel finding raises the potential for identifying therapeutic targets that may also influence outcomes.

Update: Microdialysis for Monitoring Cerebral Metabolic Dysfunction after Subarachnoid Hemorrhage

Cerebral metabolic dysfunction has been shown to extensively mediate the pathophysiology of brain injury after subarachnoid hemorrhage (SAH). The characterization of the alterations of metabolites in the brain can help elucidate pathophysiological changes occurring throughout SAH and the relationship between secondary brain injury and cerebral energy dysfunction after SAH. Cerebral microdialysis (CMD) is a tool that can measure concentrations of multiple bioenergetics metabolites in brain interstitial fluid. This review aims to provide an update on the implication of CMD on the measurement of metabolic dysfunction in the brain after SAH. A literature review was conducted through a general PubMed search with the terms “Subarachnoid Hemorrhage AND Microdialysis” as well as a more targeted search using MeSh with the search terms “Subarachnoid hemorrhage AND Microdialysis AND Metabolism.” Both experimental and clinical papers were reviewed. CMD is a suitable tool that has been used for monitoring cerebral metabolic changes in various types of brain injury. Clinically, CMD data have shown the dramatic changes in cerebral metabolism after SAH, including glucose depletion, enhanced glycolysis, and suppressed oxidative phosphorylation. Experimental studies using CMD have demonstrated a similar pattern of cerebral metabolic dysfunction after SAH. The combination of CMD and other monitoring tools has also shown value in further dissecting and distinguishing alterations in different metabolic pathways after brain injury. Despite the lack of a standard procedure as well as the presence of limitations regarding CMD application and data interpretation for both clinical and experimental studies, emerging investigations have suggested that CMD is an effective way to monitor the changes of cerebral metabolic dysfunction after SAH in real-time, and alternatively, the combination of CMD and other monitoring tools might be able to further understand the relationship between cerebral metabolic dysfunction and brain injury after SAH, determine the severity of brain injury and predict the pathological progression and outcomes after SAH. More translational preclinical investigations and clinical validation may help to optimize CMD as a powerful tool in critical care and personalized medicine for patients with SAH.

Nonconvulsive status epilepticus after surgery for ruptured intracranial aneurysms: Incidence, associated factors, and impact on the outcome

OBJECTIVE

To evaluate the incidence of nonconvulsive status epilepticus (NCSE) after surgery for ruptured intracranial aneurysms, to define factors associated with this complication, and to determine its impact on the outcome.

PATIENTS AND METHODS

Clinical and neurophysiological data of 66 patients with aneurysmal subarachnoid hemorrhage (aSAH) who underwent continuous EEG (cEEG) monitoring after microsurgical clipping (53 cases) or endovascular coiling (13 cases) of the ruptured aneurysm were analyzed retrospectively. The diagnosis of NCSE was based on the American Clinical Neurophysiology Society and Salzburg Consensus criteria.

RESULTS

NCSE was revealed in 10 patients (15 %), all of whom underwent craniotomy and aneurysm clipping. In comparison to the subgroup without NCSE, among those who were diagnosed with this complication there was a significantly greater proportion of men (70 % vs. 34 %; P = 0.041), cases with the Glasgow Coma Scale score at admission < 13 (90 % vs. 36 %; P = 0.004), the Hunt and Hess aSAH grades 3-5 (90 % vs. 45 %; P = 0.013), and hydrocephalus (70 % vs. 29 %; P = 0.044). In addition, they required a significantly longer hospital stay (medians, 62.5 vs. 39.5 days; P = 0.015) and showed trend for the lower rate of favorable disability outcomes (20 % vs. 54 %; P = 0.084).

CONCLUSIONS

NCSE is encountered rather often after the microsurgical clipping of ruptured intracranial aneurysms, especially in severely disabled patients with high-grade aSAH and/or associated hydrocpephalus, and may significantly affect the clinical course and prolong recovery. cEEG monitoring may be helpful for timely diagnosis and treatment of this complication.

Bibliometric Analysis of the Top 100 Most Cited Articles on Cerebral Vasospasm

OBJECTIVE

Bibliometric analysis reflects the scientific recognition and influential performance of a published article within its field. Our aim is to identify and analyze the top 100 most-cited articles on cerebral vasospasm.

METHODS

A title-specific search was carried out using the Scopus database. The top 100 cited articles including the keywords "Cerebral Vasospasm" AND "Vasospasm" were retrieved and stratified in a descending order: title, authors, institution, publishing journal, country of origin, year of publication, and topic of each article were studied.

RESULTS

The top 100 articles have an accumulative citation count of 20,972, with 209 average citations per article. Publication dates ranged from 1968 to 2012, with the most productive years between 1998 and 2005. Clinical studies are the most frequent category, followed by pathophysiology. The list includes 7 clinical trials, which received accumulative citations of 1525. The top cited article had received 2109 citations, with 52.7 citations per year. The top 100 articles were published across 14 countries, with most originating from the United States. The lead research institution was the University of Alberta. The most used journal was Journal of Neurosurgery.

CONCLUSIONS

Bibliometric analysis has garnered major interest in recent years. It shows the publication trends, knowledge evolution, and evidence-based practice throughout the years. The collection of highly cited articles may assist physicians in gaining a better understanding of the nature of cerebral vasospasm and optimize their clinical practice.

Microvascular platelet aggregation and thrombosis after subarachnoid hemorrhage: A review and synthesis

Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH) has been associated with numerous pathophysiological sequelae, including large artery vasospasm and microvascular thrombosis. The focus of this review is to provide an overview of experimental animal model studies and human autopsy studies that explore the temporal-spatial characterization and mechanism of microvascular platelet aggregation and thrombosis following SAH, as well as to critically assess experimental studies and clinical trials highlighting preventative therapeutic options against this highly morbid pathophysiological process. Upon review of the literature, we discovered that microvascular platelet aggregation and thrombosis occur after experimental SAH across multiple species and SAH induction techniques in a similar time frame to other components of DCI, occurring in the cerebral cortex and hippocampus across both hemispheres. We discuss the relationship of these findings to human autopsy studies. In the final section of this review, we highlight the important therapeutic options for targeting microvascular platelet aggregation and thrombosis, and emphasize why therapeutic targeting of this neurovascular pathology may improve patient care. We encourage ongoing research into the pathophysiology of SAH and DCI, especially in regard to microvascular platelet aggregation and thrombosis and the translation to randomized clinical trials.

Endogenous calcitonin gene-related peptide in cerebrospinal fluid and early quality of life and mental health after good-grade spontaneous subarachnoid hemorrhage-a feasibility series

The vasodilatory calcitonin gene-related peptide (CGRP) is excessively released after spontaneous subarachnoid hemorrhage (sSAH) and modulates psycho-behavioral function. In this pilot study, we prospectively analyzed the treatment-specific differences in the secretion of endogenous CGRP into cerebrospinal fluid (CSF) during the acute stage after good-grade sSAH and its impact on self-reported health-related quality of life (hrQoL). Twenty-six consecutive patients (f:m = 13:8; mean age 50.6 years) with good-grade sSAH were enrolled (drop out 19% (n = 5)): 35% (n = 9) underwent endovascular aneurysm occlusion, 23% (n = 6) microsurgery, and 23% (n = 6) of the patients with perimesencephalic SAH received standardized intensive medical care. An external ventricular drain was inserted within 72 h after the onset of bleeding. CSF was drawn daily from day 1–10. CGRP levels were determined via competitive enzyme immunoassay and calculated as “area under the curve” (AUC). All patients underwent a hrQoL self-report assessment (36-Item Short Form Health Survey (SF-36), ICD-10-Symptom-Rating questionnaire (ISR)) after the onset of sSAH (t₁: day 11–35) and at the 6-month follow-up (t₂). AUC CGRP (total mean ± SD, 5.7 ± 1.8 ng/ml/24 h) was excessively released into CSF after sSAH. AUC CGRP levels did not differ significantly when dichotomizing the aSAH (5.63 ± 1.77) and pSAH group (5.68 ± 2.08). aSAH patients revealed a higher symptom burden in the ISR supplementary item score (p = 0.021). Multiple logistic regression analyses corroborated increased mean levels of AUC CGRP in CSF at t₁ as an independent prognostic factor for a significantly higher symptom burden in most ISR scores (compulsive-obsessive syndrome (OR 5.741, p = 0.018), anxiety (OR 7.748, p = 0.021), depression (OR 2.740, p = 0.005), the supplementary items (OR 2.392, p = 0.004)) and for a poorer performance in the SF-36 physical component summary score (OR 0.177, p = 0.001). In contrast, at t₂, CSF AUC CGRP concentrations no longer correlated with hrQoL. To the best of our knowledge, this study is the first to correlate the levels of endogenous CSF CGRP with hrQoL outcome in good-grade sSAH patients. Excessive CGRP release into CSF may have a negative short-term impact on hrQoL and emotional health like anxiety and depression. While subacutely after sSAH, higher CSF levels of the vasodilator CGRP are supposed to be protective against vasospasm-associated cerebral ischemia, from a psychopathological point of view, our results suggest an involvement of CSF CGRP in the dysregulation of higher integrated behavior.

Long-term impairment of neurovascular coupling following experimental subarachnoid hemorrhage

CO₂-reactivity and neurovascular coupling are sequentially lost within the first 24 h after subarachnoid hemorrhage (SAH). Whether and when these impairments recover is not known. Therefore, we investigated the reactivity of pial and intraparenchymal vessels by in vivo two-photon microscopy one month after experimental SAH. C57BL/6 mice were subjected to either sham surgery or SAH by filament perforation. One month later, cerebral blood flow following CO₂-challenge and forepaw stimulation was assessed by laser Doppler fluxmetry. Diameters of pial and intraparenchymal arterioles were quantified by in vivo two-photon microscopy. One month after SAH, pial and parenchymal vessels dilated in response to CO₂. Neurovascular coupling was almost completely absent after SAH: vessel diameter did not change upon forepaw stimulation compared to a 20% increase in sham-operated mice. The current results demonstrate that neurovascular function differentially recovers after SAH: while CO₂-reactivity normalizes within one month after SAH, neurovascular coupling is still absent. These findings show an acute and persistent loss of neurovascular coupling after SAH that may serve as a link between early brain injury and delayed cerebral ischemia, two distinct pathophysiological phenomena after SAH that were so far believed not to be directly related.

Tirofiban Protocol Protects Against Delayed Cerebral Ischemia: A Case-Series Study

BACKGROUND

There has not been any effective prophylaxis for delayed cerebral ischemia delayed cerebral ischemia (DCI) since the introduction of nimodipine. Platelet inhibition may reduce the risk by preventing the formation of microthrombi. Tirofiban has been used as a single monotherapy bridge given its safety profile and controlled platelet inhibition.

OBJECTIVE

To assess the risk of DCI in aneurysmal subarachnoid hemorrhages (aSAH) patients treated with the tirofiban protocol.

METHODS

aSAH patients between December 2010 and March 2019 who were treated with stent assisted coiling or flow-diverting device were started on a continuous tirofiban infusion protocol and were compared with patients who underwent coil embolization without antiplatelet therapy. Safety analysis was performed to assess DCI, hemorrhagic, and ischemic events.

RESULTS

A total of 21 patients were included in the tirofiban series and 81 in the control group. There was no statistical difference in age, gender, Hunt-Hess grade, and Fisher scale between the 2 groups except for a higher Fisher grade II in the tirofiban group. Multivariate analysis revealed tirofiban to reduce the risk of vasospasm by 72 percent (OR .28, P = .03), without affecting the risk of hemorrhagic complications (OR = 0.50, P = .26). Tirofiban reduced the risk of symptomatic stroke endovascular procedure but it did not reach significance (P = .06). DCI, older age, and postprocedural symptomatic stroke were significant predictors of mortality. Tirofiban reduced the mortality risk, but this association was not statistically significant.

CONCLUSION

The tirofiban protocol in aSAH patients reduces the risk of DCI without conferring additional risks. This supports previous findings were antiplatelet therapy reduced DCI in human and animal models.

Association between elevated cerebrospinal fluid D-dimer levels and delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage

Delayed cerebral ischaemia (DCI) after aneurysmal subarachnoid haemorrhage (aSAH) is a major contributor to morbidity and mortality. It is currently not possible to reliably predict patients at risk of DCI after aSAH. The aim of this study was to quantify cerebrospinal fluid (CSF) D-Dimer and plasminogen levels and to investigate any association with development of DCI. Cerebrospinal fluid (CSF) samples collected from 30 patients within 72 h post-aSAH (n = 13 DCI and n = 17 non-DCI patients) were analysed. DCI was diagnosed when angiographic vasospasm was detected in the presence of new onset neurological deficit. Enzyme-linked immunosorbent assays were used to quantify D-dimer concentrations while western blotting was used to quantify plasminogen levels. Significant differences in CSF proteins between DCI and non-DCI cohorts were verified using Mann-Whitney test. Sensitivity and specificity of these proteins for detecting DCI was examined using a ROC curve and verified with a Fischer's exact test. CSF levels of D-dimer within 72 h post aSAH were significantly elevated in DCI patients (54.29 ng/ml, 25.35-105.88 ng/ml) compared to non-DCI patients (26.75 ng/ml, 6.9-45.08 ng/ml) [p = 0.03]. In our sample population, D-dimer levels above 41.1 ng/ml had a sensitivity of 69.2% and specificity of 75% for predicting DCI. CSF levels of plasminogen (DCI: 0.50 signal-intensity/μl, 0.20-0.73 signal-intensity/μl, non-DCI: 0.28 signal-intensity/μl, 0.22-0.54 signal-intensity/μl) did not differ between the DCI and non-DCI cohort (p > 0.05). Our study suggests that elevated D-dimer in the first 72 h after aSAH may be a potential predictive biomarker for DCI.

In vitro and in vivo testing of a novel local nicardipine delivery system to the brain: a preclinical study

OBJECTIVE

The management of patients with aneurysmal subarachnoid hemorrhage (aSAH) remains a highly demanding challenge in critical care medicine. Despite all efforts, the calcium channel antagonist nimodipine remains the only drug approved for improving outcomes after aSAH. However, in its current form of application, it provides less than optimal efficacy and causes dose-limiting hypotension in a substantial number of patients. Here, the authors tested in vitro the release dynamics of a novel formulation of the calcium channel blocker nicardipine and in vivo local tolerance and tissue reaction using a chronic cranial window model in mice.

METHODS

To characterize the release kinetics in vitro, dissolution experiments were performed using artificial cerebrospinal fluid over a time period of 21 days. The excipients used in this formulation (NicaPlant) for sustained nicardipine release are a mixture of two completely degradable polymers. A chronic cranial window in C57BL/6 mice was prepared, and NicaPlant slices were placed in proximity to the exposed cerebral vasculature. Epifluorescence video microscopy was performed right after implantation and on days 3 and 7 after surgery. Vessel diameter of the arteries and veins, vessel permeability, vessel configuration, and leukocyte-endothelial cell interaction were quantified by computer-assisted analysis. Immunofluorescence staining was performed to analyze inflammatory reactions and neuronal alterations.

RESULTS

In vitro the nicardipine release profile showed an almost linear curve with about 80% release at day 15 and full release at day 21. In vivo epifluorescence video microscopy showed a significantly higher arterial vessel diameter in the NicaPlant group due to vessel dilatation (21.6 ± 2.6 µm vs 17.8 ± 1.5 µm in controls, p < 0.01) confirming vasoactivity of the implant, whereas the venous diameter was not affected. Vessel dilatation did not have any influence on the vessel permeability measured by contrast extravasation of the fluorescent dye in epifluorescence microscopy. Further, an increased leukocyte-endothelial cell interaction due to the implant could not be detected. Histological analysis did not show any microglial activation or accumulation. No structural neuronal changes were observed.

CONCLUSIONS

NicaPlant provides continuous in vitro release of nicardipine over a 3-week observation period. In vivo testing confirmed vasoactivity and lack of toxicity. The local application of this novel nicardipine delivery system to the subarachnoid space is a promising tool to improve patient outcomes while avoiding systemic side effects.

Neurocritical Care: Bench to Bedside (Eds. Claude Hemphill, Michael James) Integrating and Using Big Data in Neurocritical Care

The critical care environment drives huge volumes of data, and clinicians are tasked with quickly processing this data and responding to it urgently. The neurocritical care environment increasingly involves EEG, multimodal intracranial monitoring, and complex imaging which preclude comprehensive human synthesis, and requires new concepts to integrate data into clinical care. By definition, Big Data is data that cannot be handled using traditional infrastructures and is characterized by the volume, variety, velocity, and variability of the data being produced. Big Data in the neurocritical care unit requires rethinking of data storage infrastructures and the development of tools and analytics to drive advancements in the field. Preprocessing, feature extraction, statistical inference, and analytic tools are required in order to achieve the primary goals of Big Data for clinical use: description, prediction, and prescription. Barriers to its use at bedside include a lack of infrastructure development within the healthcare industry, lack of standardization of data inputs, and ultimately existential and scientific concerns about the outputs that result from the use of tools such as artificial intelligence. However, as implied by the fundamental theorem of biomedical informatics, physicians remain central to the development and utility of Big Data to improve patient care.

Spreading Depolarizations and Subarachnoid Hemorrhage

Cortical spreading depolarizations (SD) are strongly associated with worse tissue injury and clinical outcomes in the setting of aneurysmal subarachnoid hemorrhage (SAH). Animal studies have suggested a causal relationship, and new therapies to target SDs are starting to be tested in clinical studies. A recent set of single-center randomized trials assessed the effect of the phosphodiesterase inhibitor cilostazol in patients with SAH. Cilostazol led to improved functional outcomes and SD-related metrics in treated patients through a putative mechanism of improved cerebral blood flow. Another promising therapeutic approach includes attempts to block SDs with, for example, the NMDA receptor antagonist ketamine. SDs have emerged not only as a therapeutic target but also as a potentially useful biomarker for brain injury following SAH. Additional clinical and preclinical experimental work is greatly needed to assess the generalizability of existing therapeutic trials and to better delineate the relationship between SDs, SAH, and functional outcome.

Single-Dose Intraventricular Nimodipine Microparticles Versus Oral Nimodipine for Aneurysmal Subarachnoid Hemorrhage

Background and Purpose- EG-1962 is a sustained release formulation of nimodipine administered via external ventricular drain in patients with aneurysmal subarachnoid hemorrhage. A randomized, open-label, phase 1/2a, dose-escalation study provided impetus for this study to evaluate efficacy and safety of a single intraventricular 600 mg dose of EG-1962 to patients with aneurysmal subarachnoid hemorrhage, compared with standard of care oral nimodipine. Methods- Subjects were World Federation of Neurological Surgeons grades 2-4, modified Fisher grades 2-4 and had an external ventricular drain inserted as part of standard of care. The primary end point was the proportion of subjects with favorable outcome at day 90 after aneurysmal subarachnoid hemorrhage (extended Glasgow outcome scale 6-8). The proportion of subjects with favorable outcome at day 90 on the Montreal cognitive assessment, as well as the incidence of delayed cerebral ischemia and infarction, use of rescue therapy and safety were evaluated. Results- The study was halted by the independent data monitoring board after planned interim analysis of 210 subjects (289 randomized) with day 90 outcome found the study was unlikely to achieve its primary end point. After day 90 follow-up of all subjects, the proportion with favorable outcome on the extended Glasgow outcome scale was 45% (65/144) in the EG-1962 and 42% (62/145) in the placebo group (risk ratio, 1.01 [95% CI, 0.83-1.22], P=0.95). Consistent with its mechanism of action, EG-1962 significantly reduced vasospasm (50% [69/138] EG-1962 versus 63% [91/144], P=0.025) and hypotension (7% [9/138] versus 10% [14/144]). Analysis of prespecified subject strata suggested potential efficacy in World Federation of Neurological Surgeons 3-4 subjects (46% [32/69] EG-1962 versus 32% [24/75] placebo, odds ratio, 1.22 [95% CI, 0.94-1.58], P=0.13). No safety concerns were identified that halted the study or that preclude further development. Conclusions- There was no significant increase in favorable outcome for EG-1962 compared with standard of care in the overall study population. The safety profile was acceptable. Registration- URL: https://www.clinicaltrials.gov; Unique identifier: NCT02790632.

Effect of Locally Delivered Nimodipine Microparticles on Spreading Depolarization in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Recurrent spreading depolarizations (SDs) occur in patients after aneurysmal subarachnoid hemorrhage (aSAH), resulting in metabolic stress to brain. These events are closely associated with delayed cerebral ischemia. Preclinical data suggest that the beneficial effect of nimodipine demonstrated in clinical trials may be related to inhibition of SD rather than limitation of large artery vasospasm.

METHODS

Subjects enrolled in a phase 3 trial of intraventricularly delivered, sustained-release nimodipine (EG-1962) versus standard of care oral nimodipine (NEWTON 2) who required surgical clipping had subdural strip electrodes implanted for monitoring of SD. SD was then scored blinded to NEWTON 2 allocation.

RESULTS

Five subjects underwent electrocorticography monitoring of SD. Three of five patients had SD. There were fewer SDs, a lower rate of SD, and shorter depression durations in subjects treated with EG-1962 compared to standard of care. Outcomes were worse in the standard of care group, though there were baseline imbalances.

CONCLUSIONS

These results are consistent with a beneficial effect of locally delivered nimodipine (EG-1962) on SD after aSAH in more severely injured patients who are at risk of delayed cerebral ischemia related to SD. Larger studies are warranted to test this effect.

Morphological changes of intracranial pressure quantifies vasodilatory effect of verapamil to treat cerebral vasospasm

INTRODUCTION

After aneurysmal subarachnoid hemorrhage (SAH), both proximal and distal cerebral vasospasm can contribute to the development of delayed cerebral ischemia. Intra-arterial (IA) vasodilators are a mainstay of treatment for distal arterial vasospasm, but no methods of assessing the efficacy of interventions in real time have been established.

OBJECTIVE

To introduce a new method for continuous intraprocedural assessment of endovascular treatment for cerebral vasospasm.

METHODS

The premise of our approach was that distal cerebral arterial changes induce a consistent pattern in the morphological changes of intracranial pressure (ICP) pulse. This premise was demonstrated using a published algorithm in previous papers. In this study, we applied the algorithm to calculate the likelihood of cerebral vasodilation (VDI) and cerebral vasoconstriction (VCI) from intraprocedural ICP signals that are synchronized with injection of the IA vasodilator, verapamil. Cerebral blood flow velocities (CBFVs) on bilateral cerebral arteries were studied before and after IA therapy.

RESULTS

192 recordings of patients with SAH were reviewed, and 27 recordings had high-quality ICP waveforms. The VCI was significantly lower after the first verapamil injection (0.47±0.017) than VCI at baseline (0.49±0.020, p<0.001). A larger dose of injected verapamil resulted in a larger and longer VDI increase. CBFV of the middle cerebral artery increases across the days before the injection of verapamil and decreases after IA therapy.

CONCLUSION

This study provides preliminary validation of an algorithm for continuous assessment of distal cerebral arterial changes in response to IA vasodilator infusion in patients with vasospasm and aneurysmal SAH.