The Pathophysiology of Delayed Cerebral Ischemia

Post-treatment Antiplatelet Therapy Reduces Risk for Delayed Cerebral Ischemia due to Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Delayed cerebral ischemia (DCI) has a strong impact on outcome of patients with aneurysmal subarachnoid hemorrhage (SAH). Positive effect of antiplatelet therapy on DCI rates has been supposed upon smaller SAH series.

OBJECTIVE

To analyze the benefit/risk profile of antiplatelet use in SAH patients.

METHODS

This retrospective case-control study was based on institutional observational cohort with 994 SAH patients treated between January 2003 and June 2016. The individuals with postcoiling antiplatelet therapy (aspirin with/without clopidogrel) were compared to a control group without antiplatelet therapy. Occurrence of DCI, major/minor bleeding events in the follow-up computed tomography scans, and favorable outcome at 6 mo after SAH (modified Rankin scale < 3) were compared in both groups.

RESULTS

Of 580 patients in the final analysis, 329 patients received post-treatment antiplatelet medication. There were no significant differences between the compared groups with regard to basic outcome confounders. Aspirin use was independently associated with reduced DCI risk (P < .001, adjusted odds ratio = 0.41, 95% confidence interval 0.24-0.65) and favorable outcome (P = .02, adjusted odds ratio = 1.78, 95% confidence interval 1.06-2.98). Regarding bleeding complications, aspirin was associated only with minor bleeding events (P = .02 vs P = .51 for major bleeding events).

CONCLUSION

Regular administration of aspirin might have a positive impact on DCI risk and outcome of SAH patients, without increasing the risk for clinically relevant bleeding events. In our SAH cohort, dual antiplatelet therapy showed no additional benefit on DCI risk, but increased the likelihood of major bleeding events.

Soluble ST2 Is Associated With New Epileptiform Abnormalities Following Nontraumatic Subarachnoid Hemorrhage

Background and Purpose- We evaluated the association between 2 types of predictors of delayed cerebral ischemia after nontraumatic subarachnoid hemorrhage, including biomarkers of the innate immune response and neurophysiologic changes on continuous electroencephalography. Methods- We studied subarachnoid hemorrhage patients that had at least 72 hours of continuous electroencephalography and blood samples collected within the first 5 days of symptom onset. We measured inflammatory biomarkers previously associated with delayed cerebral ischemia and functional outcome, including soluble ST2 (sST2), IL-6 (interleukin-6), and CRP (C-reactive protein). Serial plasma samples and cerebrospinal fluid sST2 levels were available in a subgroup of patients. Neurophysiologic changes were categorized into new or worsening epileptiform abnormalities (EAs) or new background deterioration. The association of biomarkers with neurophysiologic changes were evaluated using the Wilcoxon rank-sum test. Plasma and cerebrospinal fluid sST2 were further examined longitudinally using repeated measures mixed-effects models. Results- Forty-six patients met inclusion criteria. Seventeen (37%) patients developed new or worsening EAs, 21 (46%) developed new background deterioration, and 8 (17%) developed neither. Early (day, 0-5) plasma sST2 levels were higher among patients with new or worsening EAs (median 115 ng/mL [interquartile range, 73.8-197]) versus those without (74.7 ng/mL [interquartile range, 44.8-102]; P=0.024). Plasma sST2 levels were similar between patients with or without new background deterioration. Repeated measures mixed-effects modeling that adjusted for admission risk factors showed that the association with new or worsening EAs remained independent for both plasma sST2 (β=0.41 [95% CI, 0.09-0.73]; P=0.01) and cerebrospinal fluid sST2 (β=0.97 [95% CI, 0.14-1.8]; P=0.021). IL-6 and CRP were not associated with new background deterioration or with new or worsening EAs. Conclusions- In patients admitted with subarachnoid hemorrhage, sST2 level was associated with new or worsening EAs but not new background deterioration. This association may identify a link between a specific innate immune response pathway and continuous electroencephalography abnormalities in the pathogenesis of secondary brain injury after subarachnoid hemorrhage.

Serum soluble lectin-like oxidized low-density lipoprotein receptor-1 as a biomarker of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

OBJECTIVE

Delayed cerebral ischemia (DCI) greatly contributes to the high morbidity and mortality of aneurysmal subarachnoid hemorrhage (aSAH) patients. Expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) was substantially raised in the basilar arterial wall of SAH rabbits. We attempted to ascertain the relationship between serum soluble LOX-1 (sLOX-1) levels and the occurrence of DCI after aSAH.

MATERIALS AND METHODS

We enrolled 125 aSAH patients and 125 healthy controls. Serum sLOX-1 levels were quantified using commercial enzyme-linked immunosorbent assay kit. The relationship between sLOX-1 levels and DCI was analyzed utilizing the multivariate logistic regression analysis.

RESULTS

Serum sLOX-1 levels were significantly higher in stroke patients than in controls (median: 1,450.2 vs. 445.7 pg/ml, p < .001). Serum sLOX-1 levels were highly correlated with World Federation of Neurological Surgeons (WFNS) scores, Hunt-Hess scores, and modified Fisher scores (r = .574, .625, and .569, respectively). Forty-two patients (33.6%) experienced DCI. Serum sLOX-1 > 1,450.2 pg/ml, WFNS scores and modified Fisher scores were the independent predictors of DCI. Under receiver operating characteristic curve, serum sLOX-1 levels exhibited a significant discriminatory capability (area under curve 0.825, 95% confidence interval 0.747-0.887). The predictive power of serum sLOX-1 levels was similar to those of WFNS scores and modified Fisher grade (both p > .05). Moreover, serum sLOX-1 levels significantly improved their predictive capability (both p < .05).

CONCLUSIONS

Serum soluble LOX-1, in positive association with hemorrhagic severity, appears to have the potential to become a promising predictor of DCI after aSAH.

Which Protocol for Milrinone to Treat Cerebral Vasospasm Associated With Subarachnoid Hemorrhage?

BACKGROUND

Milrinone has emerged as an option to treat delayed cerebral ischemia after subarachnoid hemorrhage. However, substantial variation exists in the administration of this drug. We retrospectively assessed the effectiveness of 2 protocols in patients with angiographically proven cerebral vasospasm.

METHODS

During 2 successive periods, milrinone was administered using either a combination of intra-arterial milrinone infusion followed by intravenous administration until day 14 after initial bleeding (IA+IV protocol), or a continuous intravenous milrinone infusion for at least 7 days (IV protocol). The primary endpoint was the reversion rate of vasospastic arterial segments following the first IA infusion of milrinone (IA+IV protocol) compared with the reversion rate during the first week of IV infusion (IV protocol).

RESULTS

There were 24 and 77 consecutive patients in IA+IV and IV protocols, respectively. The reversion rate was comparable between the 2 protocols: 71% (95% confidence interval [CI], 59%-83%) in the IA+IV protocol versus 64% (95% CI, 58%-71%) in the IV protocol (P=0.36). Rescue procedures for persistence or recurrence of vasospasm, that is, mechanical angioplasty and/or IA milrinone infusion, were similar between the 2 protocols. Patients with a good neurological outcome at 1 year, that is, modified Rankin Scale scores 0-2, were comparable between the 2 protocols. Side effects of milrinone were uncommon and equally distributed within the 2 protocols.

CONCLUSIONS

These findings indicate that a continuous IV infusion of milrinone was as efficient as combined IA+IV infusion and suggest that this modality could be considered as a first easy-to-use option to treat patients with CVS.

Immune Characterization in Aneurysmal Subarachnoid Hemorrhage Reveals Distinct Monocytic Activation and Chemokine Patterns

The pathophysiology of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) is incompletely understood. Intrathecal activation of inflammatory immune cells is suspected to play a major role for the induction of DCI. The aim of this study is to identify immune cell subsets and mediators involved in the pathogenesis of DCI. We prospectively collected blood and CSF from 25 patients with aSAH at early and late time points. We performed multicolor flow cytometry of peripheral blood and CSF, analyzing immune cell activation and pro-inflammatory cyto- and chemokines. In addition to the primary immune analysis, we retrospectively analyzed immune cell dynamics in the CSF of all our SAH patients. Our results show an increased monocyte infiltration secondary to aneurysm rupture in patients with DCI. Infiltrating monocytes are defined by a non-classical (CD14^dim CD16⁺) phenotype at early stages. The infiltration is most likely triggered by the intrathecal immune activation. Here, high levels of pro-inflammatory chemokines, such as CXCL1, CXCL9, CXCL10, and CXCL11, are detected. The intrathecal cellular activation profile of monocytes was defined by upregulation of CD163 and CD86 on monocytes and a presumable later differentiation into antigen-presenting plasmacytoid dendritic cells (pDCs) and hemosiderophages. Peripheral immune activation was reflected by CD69 upregulation on T cells. Analysis of DCI prevalence, Hunt and Hess grade, and clinical outcome correlated with the degree of immune activation. We demonstrate that monocytes and T cells are activated intrathecally after aSAH and mediate a local inflammatory response which is presumably driven by chemokines. Our data shows that the distinct pattern of immune activation correlates with the prevalence of DCI, indicating a pathophysiological connection to the incidence of vasospasm.

Serum soluble lectin-like oxidized low-density lipoprotein receptor-1 concentrations and prognosis of aneurysmal subarachnoid hemorrhage

BACKGROUND

Oxidized low-density lipoprotein (ox-LDL) and its receptor, lectin-like ox-LDL receptor-1 (LOX-1) are involved in the pathogenesis of atherosclerosis. Expression of LOX-1 was substantially raised in the basilar arterial wall of subarachnoid hemorrhage (SAH) rabbits. We ascertained the relationship between serum soluble LOX-1 concentrations and functional outcome after human aneurysmal SAH.

METHODS

We enrolled 94 aneurysmal SAH patients and 94 healthy controls. Serum soluble TOX-1 concentrations were quantified using commercial enzyme-linked immunosorbent assay kit. A poor outcome was defined as Glasgow outcome scale score of 1-3.

RESULTS

Median values of serum soluble LOX-1 in stroke patients were significantly higher than those in controls (1.5 vs. 0.4 ng/ml, P < 0.001). Thirty patients (31.9%) had a poor outcome at 6 months after stroke. Serum soluble LOX-1 was a strong predictor of poor outcome (OR 5.20, 95% CI 1.25-22.04). Serum soluble LOX-1 concentrations exhibited a significant discriminatory capability (area under curve 0.811, 95% confidence interval 0.717-0.884). The predictive powers of World Federation of Neurological Surgeons grade, Hunt-Hess grade, modified Fisher grade, and serum soluble LOX-1 concentrations were comparable (all P > 0.05).

CONCLUSIONS

Serum soluble LOX-1 appears to have the potential to become a promising prognostic predictor after human aneurysmal SAH.

The role of haptoglobin and hemopexin in the prevention of delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage: a review of current literature

Delayed cerebral ischaemia (DCI) after aneurysmal subarachnoid haemorrhage (aSAH) is a major cause of mortality and morbidity. The pathophysiology of DCI after aSAH is thought to involve toxic mediators released from lysis of red blood cells within the subarachnoid space, including free haemoglobin and haem. Haptoglobin and hemopexin are endogenously produced acute phase proteins that are involved in the clearance of these toxic mediators. The aim of this review is to investigate the pathophysiological mechanisms involved in DCI and the role of both endogenous as well as exogenously administered haptoglobin and hemopexin in the prevention of DCI.

Acute changes of pro-inflammatory markers and corticosterone in experimental subarachnoid haemorrhage: A prerequisite for severity assessment

Many details of the pathophysiology of subarachnoid haemorrhage (SAH) still remain unknown, making animal experiments an indispensable tool for assessment of diagnostics and therapy. For animal protection and project authorization, one needs objective measures to evaluate the severity and burden in each model. Corticosterone is described as a sensitive stress parameter reflecting the acute burden, and inflammatory markers can be used for assessment of the extent of the brain lesion. However, the brain lesion itself may activate the hypothalamic-pituitary-adrenal-axis early after SAH, as shown for ischemic stroke, probably interfering with early inflammatory processes, thus complicating the assessment of severity and burden on the basis of corticosterone and inflammation. To assess the suitability of these markers in SAH, we evaluated the courses of corticosterone, IL-6 and TNF-α up to 6h in an acute model simulating SAH in continuously anaesthetized rats, lacking the pain and stress induced impact on these parameters. Animals were randomly allocated to sham or SAH. SAH was induced by cisterna magna blood-injection, and intracranial pressure and cerebral blood flow were measured under continuous isoflurane/fentanyl anaesthesia. Withdrawn at predetermined time points, blood was analysed by commercial ELISA kits. After 6h the brain was removed for western blot analysis of IL-6 and TNF-α. Serum corticosterone levels were low with no significant difference between sham and SAH. No activation of the HPA-axis was detectable, rendering corticosterone a potentially useful parameter for stress assessment in future chronic studies. Blood IL-6 and TNF-α increased in both groups over time, with IL-6 increasing significantly more in SAH compared to sham towards the end of the observation period. In the basal cortex, IL-6 and TNF-α increased only in SAH. The pro-inflammatory response seems to start locally in the brain, reflected by an increase in peripheral blood. An additional surgery-induced systemic inflammatory response should be considered.

Early Perfusion Computed Tomography Scan for Prediction of Vasospasm and Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE

We investigated the ability of early alteration of cerebral perfusion-computed tomography (PCT) parameters to predict the risk of vasospasm, delayed cerebral ischemia (DCI), and clinical outcome in patients with aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

A retrospective cohort study of 38 aSAH patients investigated with PCT within 48 hours after hemorrhage. Cerebral blood flow (CBF), cerebral blood volume, and mean transit time (MTT) values were recorded. Mean values were compared with clinical data. Vasospasm and DCI were determined by imaging and clinical criteria. Neurologic outcome was assessed by the modified Rankin Scale at discharge and 1-year follow-up visit.

RESULTS

More than a third (39.5%) of patients developed DCI, of whom 86.7% presented moderate-severe vasospasm. There was a significant correlation between perfusion parameters in the early phase and occurrence of DCI and vasospasm. The occurrence of DCI and vasospasm correlated significantly with lower mean early PCT values. DCI was correlated with lower mean early CBF values (P = 0.049) and vasospasm with lower mean CBF (P = 0.01) and MTT (P < 0.00001) values. MTT values of 5.5s were shown to have 94% specificity and 100% sensitivity for predicting the risk of developing vasospasm. The severity of the SAH according to the Barrow Neurological Institute scale correlated significantly with the risk of developing DCI and vasospasm, both significantly associated with unfavorable neurologic outcome (modified Rankin Scale score 3-6) (P = 0.0002 and P = 0.02, respectively).

CONCLUSIONS

Early alterations in PCT parameters and high Barrow Neurological Institute grade may identify a subgroup of patients at high risk of developing DCI and vasospasm after aSAH, thus prompting more robust preventative measures and treatment in this subgroup.

The Association Between Serum Macrophage Migration Inhibitory Factor and Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

Inflammatory processes have long been implicated in the development of delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH). Macrophage migration inhibitory factor (MIF) has been implicated in inflammation. The aim of this study was to assess whether serum levels of MIF at admission helps to predict which patients with aSAH would subsequently develop DCI. All patients with first-ever aSAH admitted between 2016 and 2017 were considered for inclusion in this prospective study. Primary study outcome was development of DCI at discharge. Serum levels of MIF, C-reactive protein (CRP), and interleukin-6 (IL-6) were tested at admission. The relation of serum levels of MIF at admission with DCI was assessed by the logistic regression models. In this study, 201 patients were included. A correlation between Hunt and Hess score and serum levels of MIF was found (r = 0.340; P < 0.001). Fifty-two of the 201 aSAH (25.9%) were defined as DCI, and the obtained MIF level in those patients was higher than in those patients without DCI [26.4 (IQR, 22.6-32.4) ng/ml vs. 20.4 (16.4-24.6) ng/ml; P < 0.001). As a continuous variable, MIF was associated with the risk of DCI. When serum level of MIF was elevated by each 1 ng/ml, the unadjusted risk of DCI was increased by 18% (OR = 1.18 [1.12-1.25], P < 0.001), while the adjusted risk was increased by 10% (1.10 [1.03-1.19], P = 0.001). With the area under the curve (AUC) of 0.780 (95% CI, 0.710-0.849), the MIF showed a great discriminatory ability for DCI than CRP (0.665, 0.582-0.748; P < 0.001) and IL-6 (0.721, 0.642-0.799; P = 0.001). Interestingly, the combined model (MIF/IL-6/CRP) improved the MIF to predict DCI (AUC of the combined model: 0.811; 95% CI, 0.751-0.871; P = 0.024). Furthermore, inclusion of MIF in the existing risk factors for the prediction of DCI enhanced the index and net reclassification improvement (NRI) (P < 0.001) and integrated discrimination improvement (IDI) (P = 0.005) values, confirming the effective reclassification and discrimination. The data showed that elevated MIF serum level accurately identifies patients at highest risk for developing DCI following aSAH.

Amplitude Instability of Somatosensory Evoked Potentials as an Indicator of Delayed Cerebral Ischemia in a Case of Subarachnoid Hemorrhage

We describe a 55-year-old male patient with a subarachnoid hemorrhage (SAH) as a result of left middle cerebral artery (MCA) aneurysm rupture, who underwent continuous electroencephalogram (EEG) and somatosensory evoked potential (cEEG-SEP) monitoring that showed an unusual SEP trend pattern. EEG was continuously recorded, and SEPs following stimulation of median nerves were recorded every 50 minutes, with the amplitude and latency of the cortical components automatically trended. An increase in intracranial pressure required a left decompressive craniectomy. cEEG-SEP monitoring was started on day 7, which showed a prolonged (24 hours) instability of SEPs in the left hemisphere. During this phase, left MCA vasospasm was demonstrated by transcranial Doppler (TCD), and computed tomography perfusion (CTP) showed a temporo-parieto-occipital ischemic penumbra. Following intravascular treatment, hypoperfusion and the amplitude of cortical SEPs improved. In our case, a prolonged phase of SEP amplitude instability during vasospasm in SAH correlated with a phase of ischemic penumbra, as demonstrated by CTP. In SAH, SEP instability during continuous monitoring is a pattern of alert that can allow treatments capable of avoiding irreversible neurological deterioration.

Increased REDD1 facilitates neuronal damage after subarachnoid hemorrhage

Regulated in development and DNA damage responses 1 (REDD1) is a highly conserved stress-response protein and can be induced by hypoxia/ischemia and DNA damage. However, it is not known whether REDD1 involves in neuronal damage caused by subarachnoid hemorrhage (SAH) that is known as one of the most important causes of disability and death worldwide. Here, we first found that SAH markedly induced the increase of REDD1 (35.467 ng/ml) in cerebrospinal fluid (CSF) of patients at acute stage (within 24 h from bleeding) compared to that of control (0.644 ng/ml). And, REDD1 level was positively correlated with severity of brain injuries (Hunt-Hess grade of SAH), but it showed an obvious decline at recovery stage 6.201 ng/ml (before discharge from hospital) because of good recovery. Moreover, it was found that the expression of REDD1 was significantly induced by hemolysate in a dose-dependent way in neurons. Knockdown of REDD1 by lentivirus encoded REDD1-shRNA could inhibit the neuronal apoptosis and LDH leakage caused by hemolysate. Importantly, the level of REDD1 in peripheral blood of SAH patients was significantly higher (4.364 ng/ml) than that of healthy persons (1.317 ng/ml) and also was positively correlated with that in CSF. Taken together, our findings provide the novel and direct evidence that REDD1 could play a critical role of process of neuronal damage caused by SAH, suggesting a new molecular target to protect brain function from SAH injury.

Endovascular Rescue Treatment for Delayed Cerebral Ischemia After Subarachnoid Hemorrhage Is Safe and Effective

Background: The implementation of rescue efforts for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage remains largely empirical for a lack of supporting evidence, while the associated risk profile is also unclear. Objective: The present study evaluates the safety and efficacy of endovascular rescue treatment (ERT, continuous intraarterial nimodipine; IAN, transcutaneous balloon angioplasty, TBA). Methods: In this prospective observational study, we assessed periprocedural complications and side effects in context of ERT. We evaluated neurological status, multimodal neuromonitoring (p_tiO₂, lactate/pyruvate ratio, transcranial doppler), and cranial imaging (CTP, DSA). All parameters were included into multivariate analysis to determine predictors for the need of retreatment. Results: We included 33 consecutive patients with 54 ERT (IAN n = 35; TBA n = 13; TBA + IAN n = 6). We recorded no serious complications and initial improvement in all parameters (neurostatus 72.3% of patients; p_tiO₂ 15.0 ± 11.7 to 25.8 ± 15.5 mmHg, p < 0.0001; lactate/pyruvate ratio 46.3 ± 27.5 to 31.0 ± 9.7, p <0.05; transcranial doppler 139.0 ± 46.3 to 98.9 ± 29.6 cm/s, p < 0.05; CTP 81.6% of patients; DSA 93.1% of patients). Retreatment (n = 16, 48.5%) was independently associated with preinterventional p_tiO₂ < 5 mmHg (p <0.01) and early (<72 h) discontinuation of IAN treatment (p = 0.08). DCI related cerebral infarction was noted in n = 8 patients (24.2%). At 3 months after discharge, favorable outcome was noted for n = 11 (35.5%) patients. Conclusion: Provided a detailed decision tree, timely ERT can provide a relatively safe and effective treatment option in those highly-selected patients undergoing multimodality monitoring where conservative treatment options are exhausted. Continuous treatment in particular may be suitable to surpass sustained DCI and was associated with a low rate of DCI related infarction and comparably high percentage of good outcome.

"Vasospasm mimic" after aneurysmal subarachnoid hemorrhage

BACKGROUND

Secondary brain injuries, such as delayed cerebral infarction (DCI), are the leading causes of disability after subarachnoid hemorrhage (SAH). Detecting DCI may be challenging, especially for patients presenting an altered level of consciousness.

CASE DESCRIPTION

We describe herein the case of a patient who developed acute hemiplegia four days after SAH, with raised blood flow velocities on transcranial Doppler (TCD), compatible with vasospasm. Finally, full work-up, using CT scan with perfusion CT, and continuous EEG, was consistent with non-convulsive seizures.

CONCLUSION

Multiple secondary complications (DCI, seizures, hydrocephalus) may occur after SAH but are clinically difficult to diagnose. A multimodal evaluation (TCD, CT or MRI, EEG) is useful in order to detect and treat late complications.

The Acute Phase of Experimental Subarachnoid Hemorrhage: Intracranial Pressure Dynamics and Their Effect on Cerebral Blood Flow and Autoregulation

Clinical presentation and neurological outcome in subarachnoid hemorrhage (SAH) is highly variable. Aneurysmal SAH (aSAH) is hallmarked by sudden increase of intracranial pressure (ICP) and acute hypoperfusion contributing to early brain injury (EBI) and worse outcome, while milder or non-aneurysmal SAH with comparable amount of blood are associated with better neurological outcome, possibly due to less dramatic changes in ICP. Acute pressure dynamics may therefore be an important pathophysiological aspect determining neurological complications and outcome. We investigated the influence of ICP variability on acute changes after SAH by modulating injection velocity and composition in an experimental model of SAH. Five hundred microliters of arterial blood (AB) or normal saline (NS) were injected intracisternally over 1 (AB₁, NS₁), 10 (AB_10, NS₁₀), or 30 min (AB₃₀) with monitoring for 6 h (n = 68). Rapid blood injection resulted in highest ICP peaks (AB₁ median 142.7 mmHg [1.Q 116.7-3.Q 230.6], AB₃₀ 33.42 mmHg [18.8-38.3], p < 0.001) and most severe hypoperfusion (AB₁ 16.6% [11.3-30.6], AB₃₀ 44.2% [34.8-59.8]; p < 0.05). However, after 30 min, all blood groups showed comparable ICP elevation and prolonged hypoperfusion. Cerebral autoregulation was disrupted initially due to the immediate ICP increase in all groups except NS₁₀; only AB₁, however, resulted in sustained impairment of autoregulation, as well as early neuronal cell loss. Rapidity and composition of hemorrhage resulted in characteristic hyperacute hemodynamic changes, with comparable hypoperfusion despite different ICP ranges. Only rapid ICP increase was associated with pronounced and early, but sustained disruption of cerebral autoregulation, possibly contributing to EBI.

Vasospasm of the basilar artery following spontaneous SAH-clinical observations and implications for vascular research

The basilar artery (BA), as a reference vessel for laboratory investigations of cerebral vasospasm (CVS) in many experimental models, warrants a sufficient blood supply despite hemodynamic changes during CVS. In a prospective evaluation study, we analyzed  patients who were admitted to our department with subarachnoid hemorrhage (SAH) for the occurrence and sequelae of CVS. Specifically, we sought to identify patients with CVS of the BA. As per institutional protocol, all patients with CVS detected in the posterior circulation had magnetic resonance imaging (MRI) examinations instead of CTA. Between January and December 2016, 74 patients were treated for spontaneous SAH. CVS occurred in 45 (61%) patients, and 31 (42%) patients developed associated cerebral infarctions (CI). CVS was significantly associated with CI (p < 0.0001; OR 44). In 18 (24.3%) patients, CVS significantly affected the basilar artery. Poor admission clinical state, younger age, and treatment modalities were significantly associated with BACVS. BACVS was more often detected in patients with severe CVS (p < 0.046; OR 4.4). Patients with BACVS developed cerebral infarction in a frequency comparable to other patients with CVS (61% vs. 70%, p = 0.7), but none of these infarctions occurred in the brain stem or pons even though vessel diameter was dramatically reduced according to CT- and/or MR-angiography. BACVS does not appear to be followed by cerebral infarction in the BA territory, presumably due to a vascular privilege of this vessel and its perforating branches. In contrast, brain ischemia can frequently be observed in the territories of other major arteries affected by CVS.

Vasospasm-related complications after subarachnoid hemorrhage: the role of patients' age and sex

BACKGROUND

Outcome of aneurysmal subarachnoid hemorrhage (SAH) depends strongly on occurrence of symptomatic vasospasm (SV) leading to delayed cerebral ischemia (DCI). Various demographic, radiographic, and clinical predictors of SV have been reported so far, partially with conflicting results. The aim of this study was to analyze the role of patients' age and sex on SV/DCI risk, especially to identify age and sex-specific risk groups.

METHODS

All patients admitted with acute SAH during a 14-year-period ending in 2016 were eligible for this study. The study endpoints were the following: SV requiring spasmolysis, occurrence of DCI in follow-up computed tomography scans and unfavorable outcome at 6 months (modified Rankin scale > 2).

RESULTS

Nine hundred ninety-four patients were included in this study. The majority was female (666; 67%). SV, DCI, and unfavorable outcomes were observed in 21.5, 21.8, and 43.6% of the patients, respectively. Younger age (p < 0.001; OR = 1.03 per year decrease) and female sex (p = 0.025; OR = 1.510) were confirmed as independent predictors of SV. Regarding the sex differences, there were three age groups for SV/DCI risk ≤ 54, 55-74, and ≥ 75 years. Male patients showed earlier decrease in SV risk (at ≥ 55 vs. ≥ 75 years in females). Therefore, SAH females aged between 55 and 74 years were at the highest risk for DCI and unfavorable outcome, as compared to younger/older females (p = 0.001, OR = 1.77/p = 0.001, OR = 1.80). In contrast, their male counterparts did not show these risk alterations (p = 0.445/p = 0.822).

CONCLUSION

After acute SAH, female and male patients seem to show different age patterns for the risk of SV and DCI. Females aged between 55 and 74 years are at particular risk of vasospasm-related SAH complications, possibly due to onset of menopause.

CLINICAL TRIAL REGISTRATION NUMBER

DRKS, Unique identifier: DRKS00008749.

Unique Contribution of Haptoglobin and Haptoglobin Genotype in Aneurysmal Subarachnoid Hemorrhage

Survivors of cerebral aneurysm rupture are at risk for significant morbidity and neurological deficits. Much of this is related to the effects of blood in the subarachnoid space which induces an inflammatory cascade with numerous downstream consequences. Recent clinical trials have not been able to reduce the toxic effects of free hemoglobin or improve clinical outcome. One reason for this may be the inability to identify patients at high risk for neurologic decline. Recently, haptoglobin genotype has been identified as a pertinent factor in diabetes, sickle cell, and cardiovascular disease, with the Hp 2-2 genotype contributing to increased complications. Haptoglobin is a protein synthesized by the liver that binds free hemoglobin following red blood cell lysis, and in doing so, prevents hemoglobin induced toxicity and facilitates clearance. Clinical studies in patients with subarachnoid hemorrhage indicate that Hp 2-2 patients may be a high-risk group for hemorrhage related complications and poor outcome. We review the relevance of haptoglobin in subarachnoid hemorrhage and discuss the effects of genotype and expression levels on the known mechanisms of early brain injury (EBI) and cerebral ischemia after aneurysm rupture. A better understanding of haptoglobin and its role in preventing hemoglobin related toxicity should lead to novel therapeutic avenues.

Continuous electroencephalography predicts delayed cerebral ischemia after subarachnoid hemorrhage: A prospective study of diagnostic accuracy

OBJECTIVE

Delayed cerebral ischemia (DCI) is a common, disabling complication of subarachnoid hemorrhage (SAH). Preventing DCI is a key focus of neurocritical care, but interventions carry risk and cannot be applied indiscriminately. Although retrospective studies have identified continuous electroencephalographic (cEEG) measures associated with DCI, no study has characterized the accuracy of cEEG with sufficient rigor to justify using it to triage patients to interventions or clinical trials. We therefore prospectively assessed the accuracy of cEEG for predicting DCI, following the Standards for Reporting Diagnostic Accuracy Studies.

METHODS

We prospectively performed cEEG in nontraumatic, high-grade SAH patients at a single institution. The index test consisted of clinical neurophysiologists prospectively reporting prespecified EEG alarms: (1) decreasing relative alpha variability, (2) decreasing alpha-delta ratio, (3) worsening focal slowing, or (4) late appearing epileptiform abnormalities. The diagnostic reference standard was DCI determined by blinded, adjudicated review. Primary outcome measures were sensitivity and specificity of cEEG for subsequent DCI, determined by multistate survival analysis, adjusted for baseline risk.

RESULTS

One hundred three of 227 consecutive patients were eligible and underwent cEEG monitoring (7.7-day mean duration). EEG alarms occurred in 96.2% of patients with and 19.6% without subsequent DCI (1.9-day median latency, interquartile range = 0.9-4.1). Among alarm subtypes, late onset epileptiform abnormalities had the highest predictive value. Prespecified EEG findings predicted DCI among patients with low (91% sensitivity, 83% specificity) and high (95% sensitivity, 77% specificity) baseline risk.

INTERPRETATION

cEEG accurately predicts DCI following SAH and may help target therapies to patients at highest risk of secondary brain injury. Ann Neurol 2018;83:958-969.

Bilirubin Oxidation Products and Cerebral Vasoconstriction

Key evidence in support of the hypothesis that bilirubin oxidation products (BOXes) contribute to the vasoconstriction associated with subarachnoid hemorrhage (SAH) are the (1) presence of BOXes in cerebral spinal fluid from SAH patients and (2) ability of one or more BOXes to elicit vasoconstriction. We critically evaluate this key evidence, detail where gaps remain, and describe recent approaches that will address these gaps.

Intracortical electrophysiological correlates of blood flow after severe SAH: A multimodality monitoring study

Subarachnoid hemorrhage (SAH) is a devastating form of stroke. Approximately one in four patients develop progressive neurological deterioration and silent infarction referred to as delayed cerebral ischemia (DCI). DCI is a complex, multifactorial secondary brain injury pattern and its pathogenesis is not fully understood. We aimed to study the relationship between cerebral blood flow (CBF) and neuronal activity at both the cortex and in scalp using electroencephalography (EEG) in poor-grade SAH patients undergoing multimodality intracranial neuromonitoring. Twenty patients were included, of whom half had DCI median 4.7 days (interquartile range (IQR): 4.0-5.6) from SAH bleed. The rate of decline in regional cerebral blood flow (rCBF) was significant in both those with and without DCI and occurred between days 4 and 7 post-SAH. The scalp EEG alpha-delta ratio declined early in those with DCI. In the group without DCI, CBF and cortical EEG alpha-delta ratio were correlated (r = 0.53; p <  0.01) and in the group without DCI, inverse neurovascular coupling was observed at CPP <  80 mmHg. We found preliminary evidence that as patients enter the period of highest risk for the development of DCI, the absence of neurovascular coupling may act as a possible pathomechanism in the development of ischemia following SAH.

Vasoconstriction and Impairment of Neurovascular Coupling after Subarachnoid Hemorrhage: a Descriptive Analysis of Retinal Changes

Impaired cerebral autoregulation and neurovascular coupling (NVC) contribute to delayed cerebral ischemia after subarachnoid hemorrhage (SAH). Retinal vessel analysis (RVA) allows non-invasive assessment of vessel dimension and NVC hereby demonstrating a predictive value in the context of various neurovascular diseases. Using RVA as a translational approach, we aimed to assess the retinal vessels in patients with SAH. RVA was performed prospectively in 24 patients with acute SAH (group A: day 5-14), in 11 patients 3 months after ictus (group B: day 90 ± 35), and in 35 age-matched healthy controls (group C). Data was acquired using a Retinal Vessel Analyzer (Imedos Systems UG, Jena) for examination of retinal vessel dimension and NVC using flicker-light excitation. Diameter of retinal vessels-central retinal arteriolar and venular equivalent-was significantly reduced in the acute phase (p < 0.001) with gradual improvement in group B (p < 0.05). Arterial NVC of group A was significantly impaired with diminished dilatation (p < 0.001) and reduced area under the curve (p < 0.01) when compared to group C. Group B showed persistent prolonged latency of arterial dilation (p < 0.05). Venous NVC was significantly delayed after SAH compared to group C (A p < 0.001; B p < 0.05). To our knowledge, this is the first clinical study to document retinal vasoconstriction and impairment of NVC in patients with SAH. Using non-invasive RVA as a translational approach, characteristic patterns of compromise were detected for the arterial and venous compartment of the neurovascular unit in a time-dependent fashion. Recruitment will continue to facilitate a correlation analysis with clinical course and outcome.

The Role of Thromboinflammation in Delayed Cerebral Ischemia after Subarachnoid Hemorrhage

Delayed cerebral ischemia (DCI) is a major determinant of patient outcome following aneurysmal subarachnoid hemorrhage. Although the exact mechanisms leading to DCI are not fully known, inflammation, cerebral vasospasm, and microthrombi may all function together to mediate the onset of DCI. Indeed, inflammation is tightly linked with activation of coagulation and microthrombi formation. Thromboinflammation is the intersection at which inflammation and thrombosis regulate one another in a feedforward manner, potentiating the formation of thrombi and pro-inflammatory signaling. In this review, we will explore the role(s) of inflammation and microthrombi in subarachnoid hemorrhage (SAH) pathophysiology and DCI, and discuss the potential of targeting thromboinflammation to prevent DCI after SAH.

Delayed Cerebral Ischemia after Subarachnoid Hemorrhage: Beyond Vasospasm and Towards a Multifactorial Pathophysiology

PURPOSE OF REVIEW

Delayed cerebral ischemia (DCI) is common after subarachnoid hemorrhage (SAH) and represents a significant cause of poor functional outcome. DCI was mainly thought to be caused by cerebral vasospasm; however, recent clinical trials have been unable to confirm this hypothesis. Studies in humans and animal models have since supported the notion of a multifactorial pathophysiology of DCI. This review summarizes some of the main mechanisms under investigation including cerebral vascular dysregulation, microthrombosis, cortical spreading depolarizations, and neuroinflammation.

RECENT FINDINGS

Recent guidelines have differentiated between DCI and angiographic vasospasm and have highlighted roles of the microvasculature, coagulation and fibrinolytic systems, cortical spreading depressions, and the contribution of the immune system to DCI. Many therapeutic interventions are underway in both preclinical and clinical studies to target these novel mechanisms as well as studies connecting these mechanisms to one another. Clinical trials to date have been largely unsuccessful at preventing or treating DCI after SAH. The only successful pharmacologic intervention is the calcium channel antagonist, nimodipine. Recent studies have provided evidence that cerebral vasospasm is not the sole contributor to DCI and that additional mechanisms may play equal if not more important roles.

Effects of erythropoietin and methylprednisolone on AQP4 expression in astrocytes

Methylprednisolone sodium succinate (MPSS) has been suggested as a treatment for spinal cord injury (SCI), but its use has been limited due to its adverse effects. Erythropoietin (EPO) has been suggested as a promising candidate for limiting SCI in mammals. The aim of the present study was to investigate the effects of EPO in combination with MPSS on astrocytes following ischemic injury in vitro. Astrocytes were isolated from the cerebral cortex of postnatal day 3 Sprague-Dawley rats and cultured in vitro. Astrocyte ischemic injury was induced by oxygen and glucose deprivation for 4 h, and reperfusion was simulated by subsequent culture under normoxic conditions. The effects of EPO and MPSS on the expression of aquaporin-4 (AQP4) were investigated. Ischemic astrocytes were treated with EPO (10 U/ml), MPSS (10 µg/ml), or EPO (10 U/ml) in combination with MPSS (10 µg/ml) during reperfusion. The cell viability of astrocytes was assessed using an MTT assay. The mRNA and protein expression levels of AQP4 were determined using reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. The role of the protein kinase C (PKC) signaling pathway in the molecular mechanisms underlying the effects of EPO and MPSS was also investigated. The present results demonstrated that following treatment with EPO and MPSS, the mRNA expression levels of AQP4 were upregulated and cell viability was enhanced. EPO and MPSS effectively inhibited the oxygen and glucose deprivation-mediated downregulation of AQP4 following reperfusion. In addition, the combined treatment with EPO and MPSS exhibited higher AQP4 expression levels and cell viability compared with each treatment alone. Finally, the effects of EPO and MPSS on AQP4 expression were partially reversed by pretreatment with the PKC inhibitor Ro 31–8220. The present study indicated that EPO and MPSS had a synergistic effect on AQP4 expression following reperfusion, and suggest that they may be combined in the treatment of SCI.

An introduction to the pathophysiology of aneurysmal subarachnoid hemorrhage

Pathophysiological processes following subarachnoid hemorrhage (SAH) present survivors of the initial bleeding with a high risk of morbidity and mortality during the course of the disease. As angiographic vasospasm is strongly associated with delayed cerebral ischemia (DCI) and clinical outcome, clinical trials in the last few decades focused on prevention of these angiographic spasms. Despite all efforts, no new pharmacological agents have shown to improve patient outcome. As such, it has become clear that our understanding of the pathophysiology of SAH is incomplete and we need to reevaluate our concepts on the complex pathophysiological process following SAH. Angiographic vasospasm is probably important. However, a unifying theory for the pathophysiological changes following SAH has yet not been described. Some of these changes may be causally connected or present themselves as an epiphenomenon of an associated process. A causal connection between DCI and early brain injury (EBI) would mean that future therapies should address EBI more specifically. If the mechanisms following SAH display no causal pathophysiological connection but are rather evoked by the subarachnoid blood and its degradation production, multiple treatment strategies addressing the different pathophysiological mechanisms are required. The discrepancy between experimental and clinical SAH could be one reason for unsuccessful translational results.

D-dimer may predict poor outcomes in patients with aneurysmal subarachnoid hemorrhage: a retrospective study

Serum biomarkers may play a reliable role in predicting the outcomes of patients with aneurysmal subarachnoid hemorrhage. This study retrospectively analyzed the relationship between serum biomarkers on admission and outcomes in patients with aneurysmal subarachnoid hemorrhage. We recruited 146 patients with aneurysmal subarachnoid hemorrhage who were treated in Renmin Hospital of Wuhan University of China between 1 May 2014 and 30 March 2016. There were 57 males and 89 females included and average age of included patients was 57.03 years old. Serum samples were taken immediately on admission (within 48 hours after initial hemorrhage) and the levels of serum biomarkers were detected. Baseline information, complications, and outcomes at 6 months were recorded. Univariate and multivariate logistic regression analyses were used to explore the relationship between biomarkers and clinical outcomes. Receiver operating characteristic curves were obtained to investigate the possibility of the biomarkers predicting prognosis. Of the 146 patients, 102 patients achieved good outcomes and 44 patients had poor outcomes. Univariate and multivariate analyses showed that high World Federation of Neurosurgical Societies grade, high serum D-dimer levels, and high neurological complications were significantly associated with poor outcomes. Receiver operating characteristic curves verified that D-dimer levels were associated with poor outcomes. D-dimer levels strongly correlated with neurological complications. In conclusion, we suggest that D-dimer levels are a good independent prognostic factor for poor outcomes in patients with aneurysmal subarachnoid hemorrhage.