Health outcomes 1 year after subarachnoid hemorrhage: An international population-based study. The Australian Cooperative Research on Subarachnoid Hemorrhage Study Group

The brief executive language screen: sensitivity and specificity in acute to early sub-acute stroke

INTRODUCTION

Propositional language and underlying executive functions can be impaired post-stroke and affect communication and quality of life. Current stroke screening tools are largely tailored to patients with aphasia, being either non-verbal or focussed on core language skills such as naming and repetition. The Brief Executive Language Screening Test (BELS) is a newly developed cognitive screening tool that assesses memory, oral apraxia, core language, as well as propositional language and associated executive functions that can be impacted and overlooked in stroke patients without aphasia. This study examines BELS sensitivity and specificity, and performance in acute to early sub-acute stroke relative to controls.

METHOD

Cross-sectional BELS data from 88 acute left and right hemisphere stroke patients (within 7 weeks of stroke) and 116 age-matched healthy controls were compared using independent samples t-tests. ROC Curve Analysis was performed to determine a cutoff score for the BELS.

RESULTS

Left and right stroke patients were reduced on all propositional language subtests, and executive function subtests of inhibition, strategy, and selection. Differences were also observed for Oral Apraxia, Naming, and Memory. By contrast, Word Comprehension and Repetition, and Sentence Completion Initiation (after corrections applied) did not differ between groups. A total BELS score of 79.25/100 was highly sensitive (.89) and specific (.89) when classifying stroke patients and healthy controls.

CONCLUSION

The BELS is brief, sensitive, suitable for bedside administration, and can aid in detection and rehabilitation of subtle executive language impairments. This in turn will help improve relationships and quality of life post-stroke.

Longitudinal Association of Health Satisfaction With Functional Status and Income Satisfaction in Stroke Survivors

IMPORTANCE

Although cross-sectional studies have reported the relationships among performance of activities of daily living (ADLs), income satisfaction, and health satisfaction, longitudinal associations in stroke survivors remain unclear.

OBJECTIVE

To examine the effects of ADL function and income satisfaction on health satisfaction over time in stroke survivors.

DESIGN

Retrospective longitudinal study designs with latent growth curve models (LGMs) to control for time-varying and time-invariant covariates.

SETTING

Community.

PARTICIPANTS

A total of 198 stroke survivors.

OUTCOMES AND MEASURES

Self-reported ADL performance, income satisfaction, and health satisfaction.

RESULTS

The average age of participants was 70.68 yr (SD = 8.09; 107 men, 91 women). Each LGM showed that an increase in ADL score (standardized β = 0.116∼0.296, all ps < .05) and income satisfaction (standardized β = 0.513∼0.726, all ps < .001) positively predicted health satisfaction over time, even after controlling for time-varying annual income, demographics, and behavioral characteristics. The fit results of all LGMs were within the acceptable range: χ2(47) = 66.378, p = .0327; χ2(47) = 57.742, p = .1355; root-mean-square error of approximation, <0.08; comparative fit index and Tucker-Lewis index, >0.90; standardized root-mean-square residual, <0.05.

CONCLUSIONS AND RELEVANCE

Because ADLs are significant modifiable health satisfaction factors, occupational therapy practitioners would need to focus more closely on ADL training in clinical settings. Furthermore, referring those clients to appropriate vocational rehabilitation to improve their income satisfaction would be necessary. Plain-Language Summary: This study recognizes the unique challenges and opportunities that arise when stroke survivors are preparing to return to their communities by emphasizing the significance of ADL training and income satisfaction during this stage of recovery. The study suggests that the therapeutic use of ADL training and income satisfaction could increase health satisfaction for stroke survivors. Therefore, comprehensive ADL training, as an occupational therapy intervention, could be crucial for stroke survivors who are preparing to return to their community from a clinical setting. Furthermore, connecting with vocational rehabilitation could also be important for improving income satisfaction for stroke survivors who are preparing to return to a community.

MRI-visible enlarged perivascular spaces in basal ganglia rather than centrum semiovale was associated with aneurysmal subarachnoid hemorrhage

Background

The subarachnoid space is continuous with the perivascular compartment in the central nervous system. However, whether the topography and severity of enlarged perivascular spaces (EPVS) correlates with spontaneous subarachnoid hemorrhage (SAH) remains unknown. Based on the underlying arteriopathy distributions, we hypothesized that EPVS in basal ganglia (BG-EPVS) are more closely associated with aneurysmal subarachnoid hemorrhage (aSAH) than other SAH without aneurysm.

Methods

Magnetic resonance imaging (MRI) scans of 271 consecutive SAH survivors with and without aneurysm were analyzed for EPVS and other markers of imaging data. In the subgroup analysis, we compared the clinical characteristics and EPVS of SAH participants with and without pre-existing known risk factors (hypertension, diabetes, and smoking history) using multivariable logistic regression.

Results

Patients with aSAH (n = 195) had a higher severity of BG-EPVS and centrum semiovale EPVS (CSO-EPVS) than those without aneurysm (n = 76). Importantly, BG-EPVS predominance pattern (BG-EPVS>CSO-EPVS) only existed in aSAH survivors rather than other SAH without aneurysm. In the subgroup analysis, interestingly, we also found that a high degree of BG-EPVS showed an independent relationship with aSAH in patients without pre-existing risk factors (e.g., hypertension).

Conclusion

In this cohort study, BG-EPVS predominance pattern was associated with aSAH patients compared with those without aneurysm. Moreover, BG-EPVS still showed a strong association with aSAH survivors without pre-existing vascular risk factors. Our present study suggested the BG-EPVS as a potential MRI-visible characteristic would shed light on the pathogenesis of glymphatic function at the skull base for aSAH.

Validity of the modified Rankin Scale in patients with aneurysmal subarachnoid hemorrhage: a randomized study

PURPOSE

The modified Rankin Scale (mRS), a clinician-reported outcome measure of global disability, has never been validated in patients with aneurysmal subarachnoid hemorrhage (aSAH). The aims of this study are to assess: (1) convergent validity of the mRS; (2) responsiveness of the mRS; and (3) the distribution of mRS scores across patient-reported outcome measures (PROMs).

METHODS

This is a prospective randomized multicenter study. The mRS was scored by a physician for all patients, and subsequently by structured interview for half of the patients and by self-assessment for the other half. All patients completed EuroQoL 5D-5L, RAND-36, Stroke Specific Quality of Life scale (SS-QoL) and Global Perceived Effect (GPE) questionnaires. Convergent validity and responsiveness were assessed by testing hypotheses.

RESULTS

In total, 149 patients with aSAH were included for analysis. The correlation of the mRS with EQ-5D-5L was r = - 0.546, while with RAND-36 physical and mental component scores the correlation was r = - 0.439and r = - 0.574 respectively, and with SS-QoL it was r = - 0.671. Three out of four hypotheses for convergent validity were met. The mRS assessed through structured interviews was more highly correlated with the mental component score than with the physical component score of RAND-36. Improvement in terms of GPE was indicated by 83% of patients; the mean change score of these patients on the mRS was - 0.08 (SD 0.915). None of the hypotheses for responsiveness were met.

CONCLUSION

The results show that the mRS generally correlates with other instruments, as expected, but it lacks responsiveness. A structured interview of the mRS is best for detecting disabling neuropsychological complaints.

REGISTRATION

URL: https://trialsearch.who.int ; Unique identifier: NL7859, Date of first administration: 08-07-2019.

Health-related quality of life of patients with aneurysmal subarachnoid hemorrhage who were classified as having "good outcomes"

BACKGROUND

This study aimed to understand the health-related quality of life (HRQoL) of patients with aneurysmal subarachnoid hemorrhage (aSAH) classified as having "good outcomes" and determine associated sociodemographic, psychological, and clinical factors.

METHODS

Participants were 86 patients with aSAH with modified Rankin Scale (mRS) scores of 0-2 in our hospital between February 2003 and April 2014. Participants completed self-report questionnaires examining sociodemographic characteristics and the following self-rating scales: the hospital anxiety and depression scale, Pittsburgh sleep quality index, and EuroQoL-5 Dimension Index (EQ-5D). Further, we retrospectively reviewed clinical data from medical records and radiologic images. Average EQ-5D scores for each variable were compared using Student's t-test and analysis of variance. Correlations between EQ-5D and continuous variables were examined using Pearson correlation analysis. Factors associated with EQ-5D were then examined using univariate and stepwise multivariate analyses through simple and multiple regression.

RESULTS

The mean age of the 86 participants was 56.87 ± 10.28 years (range: 29-79 years), while the mean EQ-5D value was 0.738 ± 0.169. There were 54 women (62.8 %) and 33 men (37.2 %). The participants had depressive symptoms (30.2 %), anxiety (10.5 %), and sleep problems (51.2 %). Regarding sociodemographic variables, educational level (p = 0.017) and monthly income (p = 0.037) were positively correlated with HRQoL. Depressive symptoms (r = -0.505, p < 0.001), anxiety (r = -0.498, p < 0.001), sleep problems (r = -0.265, p = 017), and mRS (r = -0.352, p = 0.001) were negatively correlated with HRQoL. Depressive symptoms, diabetes mellitus, and past psychiatric history explained 48.8 % of the variance in HRQoL in good outcome aSAH according to stepwise multiple regression analysis.

CONCLUSIONS

Patients with good outcome aSAH had low EQ-5D values, which were negatively correlated with depressive symptoms, anxiety, and sleep problems. In addition, HRQoL in good outcome aSAH is associated with depressive symptoms, diabetes mellitus, and past psychiatric disease history. Depressive symptoms, anxiety, and sleep problems are frequent in patients with good outcome aSAH, and mediation of these factors may help improve HRQoL.

Functional effects of haemoglobin can be rescued by haptoglobin in an in vitro model of subarachnoid haemorrhage

During subarachnoid haemorrhage, a blood clot forms in the subarachnoid space releasing extracellular haemoglobin (Hb), which causes oxidative damage and cell death in surrounding tissues. High rates of disability and cognitive decline in SAH survivors are attributed to loss of neurons and functional connections during secondary brain injury. Haptoglobin sequesters Hb for clearance, but this scavenging system is overwhelmed after a haemorrhage. Whilst exogenous haptoglobin application can attenuate cytotoxicity of Hb in vitro and in vivo, the functional effects of sub-lethal Hb concentrations on surviving neurons and whether cellular function can be protected with haptoglobin treatment remain unclear. Here we use cultured neurons to investigate neuronal health and function across a range of Hb concentrations to establish the thresholds for cellular damage and investigate synaptic function. Hb impairs ATP concentrations and cytoskeletal structure. At clinically relevant but sub-lethal Hb concentrations, we find that synaptic AMPAR-driven currents are reduced, accompanied by a reduction in GluA1 subunit expression. Haptoglobin co-application can prevent these deficits by scavenging free Hb to reduce it to sub-threshold concentrations and does not need to be present at stoichiometric amounts to achieve efficacy. Haptoglobin itself does not impair measures of neuronal health and function at any concentration tested. Our data highlight a role for Hb in modifying synaptic function in surviving neurons, which may link to impaired cognition or plasticity after SAH and support the development of haptoglobin as a therapy for subarachnoid haemorrhage.

The SOS-SAH questionnaire in clinical practice: a multi-method evaluation study

BACKGROUND

In patients with mild disabilities after aneurysmal subarachnoid hemorrhage (aSAH), invisible symptoms might be easily overlooked during consultations in the outpatient clinic. We hypothesize that the Questionnaire for the Screening of Symptoms in aneurysmal Subarachnoid Hemorrhage (SOS-SAH), a disease-specific patient-reported outcome measure, might aid in screening for symptoms after aSAH. The objective of this explorative study is to evaluate the perceived impact of using the SOS-SAH in daily clinical practice for patients after aSAH, as well as to explore potential barriers to further implementation.

METHODS

This multi-method study consists of a quantitative and a qualitative component. To evaluate differences in quality of care, a patient experience survey was sent to patients receiving usual care and to patients who received the SOS-SAH. A multiple linear regression model was applied, with the intervention group and case mix adjusters as independent variables. We described differences in the number of symptoms discussed between patients receiving usual care and those receiving care post-implementation. Following implementation, 16 patients and 6 healthcare professionals were interviewed about their perceptions concerning the impact of and barriers to using the SOS-SAH. A thematic analysis was performed to identify the main themes.

RESULTS

The survey did not reveal any differences between the usual-care group and the post-implementation group on the scales of the patient experience survey. After implementation of the SOS-SAH, the number of symptoms discussed during consultation did not increase. The interviews suggest that the SOS-SAH may improve the preparation of patients by providing them with greater insight into their complaints and by raising issues for the consultation. It could also enhance the structure and efficiency of consultation, in addition to improving communication about issues that matter to patients. All patients and healthcare professionals recommended continuing the use of the SOS-SAH in daily practice.

CONCLUSIONS

Although no quantitative improvements were found in patient experience and symptoms discussed during consultation, implementation of the SOS-SAH could aid in screening for symptoms in patients after aSAH, and it might have a positive influence on patient preparation, while helping to structure consultations between patients and healthcare professionals.

Duration between aneurysm rupture and treatment and its association with outcome in aneurysmal subarachnoid haemorrhage

Timely treatment of aneurysmal subarachnoid haemorrhage (aSAH) is key to prevent further rupture and poor outcome. We evaluated complications and outcome adjusting for time from haemorrhage to treatment. Retrospective analysis of aSAH patients admitted between 2006 and 2020. Data was collected using standardized case report forms. We compared risk factors using multivariable logistic regression. We included 853 patients, 698 (81.8%) were treated within 24 h. Patients with higher Hunt and Hess grades were admitted and treated significantly faster than those with lower grades (overall p-value < 0.001). Fifteen patients (1.8%) rebled before intervention. In the multivariable logistic analysis adjusting for timing, Barrow Neurological Institute score and intracerebral haemorrhage were significantly associated with rebleeding (overall p-value 0.006; OR 3.12, 95%CI 1.09-8.92, p = 0.03, respectively) but timing was not. Treatment > 24 h was associated with higher mortality and cerebral infarction in only the subgroup of lower grades aSAH (OR 3.13, 1.02-9.58 95%CI, p-value = 0.05; OR 7.69, 2.44-25.00, p-value < 0.001, respectively). Therefore treatment > 24 h after rupture is associated with higher mortality and cerebral infarction rates in lower grades aSAH. Delay in treatment primarily affects lower grade aSAH patients. Patients with lower grade aSAH ought to be treated with the same urgency as higher-grade aSAH.

Subarachnoid Hemorrhage During Pregnancy and Puerperium: A Population-Based Study

BACKGROUND

Pregnancy-related subarachnoid hemorrhage (pSAH) is rare, but it causes high mortality and morbidity. Nevertheless, data on pSAH are limited. The objectives here were to examine the incidence trends, causes, risk factors, and outcomes of pSAH in a nationwide population-based cohort study in Finland covering 30 years.

METHODS

We performed a retrospective population-based cohort study and nested case-control study in Finland for the period 1987-2016 (Stroke in Pregnancy and Puerperium in Finland). The Medical Birth Register was linked to the Hospital Discharge Register to identify women with incident stroke during pregnancy or puerperium. A subcohort of women with SAH is included in this analysis. The temporal connection of SAH to pregnancy and clinical details were verified from patient records.

RESULTS

The unadjusted incidence of pSAH was 3.21 (95% CI, 2.46-4.13) per 100 000 deliveries. No significant increase occurred in the incidence throughout the study period. However, the age of the mother had a significant increasing effect on the incidence. In total, 77% of patients suffered an aneurysmal pSAH, resulting in death in 16.3% of women and with only 68.2% achieving good recovery (modified Rankin Scale score 0-2) at 3 months. Patients with nonaneurysmal pSAH recovered well. The significant risk factors for pSAH were smoking (odds ratio, 3.27 [1.56-6.86]), prepregnancy hypertension (odds ratio, 12.72 [1.39-116.46]), and pre-eclampsia/eclampsia (odds ratio, 3.88 [1.00-15.05]).

CONCLUSIONS

The incidence of pSAH has not changed substantially over time in Finland. The majority of pSAH cases were aneurysmal and women with aneurysm had considerable mortality and morbidity. Counseling of pregnant women about smoking cessation and monitoring of blood pressure and symptoms of pre-eclampsia are important interventions to prevent pSAH.

The value of early CT perfusion parameters for predicting delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

Delayed cerebral ischemia (DCI) is a devastating complication of aneurysmal subarachnoid hemorrhage (aSAH). We aim to investigate the efficacy of early CT perfusion (CTP) parameters for predicting DCI in patients with aSAH. The search was conducted in five databases (PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, and China Biology Medicine database). Studies were reviewed by two independent authors, and the included studies were assessed for methodological quality. Fifteen studies with 882 participants were included for the final analysis. The meta-analysis of quantitative parameters showed that mean transit time represented the most valuable predictor when the calculation of the mean value was uniformed (MD 0.30 s, 95% CI: 0.10 to 0.49 s, P = 0.003). Semi-quantitative parameters using relative values or index scores were also widely used to minimize undue variations derived from patients, operators, machines, and software. Studies also demonstrated that these relative parameters had better predictive accuracy than corresponding absolute parameters. Perfusion thresholds in each study were incomparable, and the results warranted further validation. The best threshold for the prediction was 0.9 using the relative cerebral blood flow parameter (sensitivity 97% and specificity 89%). We conclude that CTP in the early phase is a promising tool for predicting DCI in aSAH patients. However, the parameters require standardization. Future studies with prospective, multi-centered design and large sample size are needed to validate the thresholds and optimize the parameters.

SIRT1 mediates hypoxic postconditioning- and resveratrol-induced protection against functional connectivity deficits after subarachnoid hemorrhage

Functional connectivity (FC) is a sensitive metric that provides a readout of whole cortex coordinate neural activity in a mouse model. We examine the impact of experimental SAH modeled through endovascular perforation, and the effectiveness of subsequent treatment on FC, through three key questions: 1) Does the endovascular perforation model of SAH induce deficits in FC; 2) Does exposure to hypoxic conditioning provide protection against these FC deficits and, if so, is this neurovascular protection SIRT1-mediated; and 3) does treatment with the SIRT1 activator resveratrol alone provide protection against these FC deficits? Cranial windows were adhered on skull-intact mice that were then subjected to either sham or SAH surgery and either left untreated or treated with hypoxic post-conditioning (with or without EX527) or resveratrol for 3 days. Mice were imaged 3 days post-SAH/sham surgery, temporally aligned with the onset of major SAH sequela in mice. Here we show that the endovascular perforation model of SAH induces global and network-specific deficits in FC by day 3, corresponding with the time frame of DCI in mice. Hypoxic conditioning provides SIRT1-mediated protection against these network-specific FC deficits post-SAH, as does treatment with resveratrol. Conditioning-based strategies provide multifaceted neurovascular protection in experimental SAH.

Aneurysmal subarachnoid hemorrhage in Germany between 2005 and 2018: a nationwide observational study

BACKGROUND

In recent decades, the global incidence of aneurysmal subarachnoid hemorrhage (aSAH) has declined. However, significant regional differences exist. We present the first comprehensive analysis of time trends in the incidence of aSAH and case fatality in Germany.

METHODS

All patients hospitalized with aSAH in Germany between 2005 and 2018 were identified using International classification of disease (ICD10) codes I60.0 to I60.7.

RESULTS

A total of 101,105 cases were included. The incidence of aSAH in Germany decreased at a mean annual rate of 0.5 % (p=0.003) from 8.9 per 100,000 population in 2005 to 8.2 in 2018. Over time, incidences of aSAH declined among patients younger than 55 years and patients aged 70-79 years, increased among ages 60-64 years and remained stable in age groups 65-69 and 85-89 years. This corresponded to an increase in the mean age of aSAH onset from 55.6 (±14.3) to 59.0 (±14.0) years. Throughout the study period, the mean age of aSAH onset was higher in women compared to men (58.3 ±14.4 years vs. 56.1 ±14.1 years). There were no changes in in-hospital case fatality (16.2 vs. 16.6%, p=0.18), but the duration of hospital stay increased significantly from 19.7 to 24.8 days (p<0.001). The most frequent aSAH associated aneurysm location was the anterior circulation throughout the entire study period.

CONCLUSIONS

In Germany, the incidence of aSAH decreased between 2005 and 2018, especially in younger parts of the population. This may reflect effects of lifestyle adjustments most pronounced in younger age groups.

Depolarization time and extracellular glutamate levels aggravate ultraearly brain injury after subarachnoid hemorrhage

Early brain injury after aneurysmal subarachnoid hemorrhage (SAH) worsens the neurological outcome. We hypothesize that a longer duration of depolarization and excessive release of glutamate aggravate neurological outcomes after SAH, and that brain hypothermia can accelerate repolarization and inhibit the excessive release of extracellular glutamate and subsequent neuronal damage. So, we investigated the influence of depolarization time and extracellular glutamate levels on the neurological outcome in the ultra-early phase of SAH using a rat injection model as Experiment 1 and then evaluated the efficacy of brain hypothermia targeting ultra-early brain injury as Experiment 2. Dynamic changes in membrane potentials, intracranial pressure, cerebral perfusion pressure, cerebral blood flow, and extracellular glutamate levels were observed within 30 min after SAH. A prolonged duration of depolarization correlated with peak extracellular glutamate levels, and these two factors worsened the neuronal injury. Under brain hypothermia using pharyngeal cooling after SAH, cerebral perfusion pressure in the hypothermia group recovered earlier than that in the normothermia group. Extracellular glutamate levels in the hypothermia group were significantly lower than those in the normothermia group. The early induction of brain hypothermia could facilitate faster recovery of cerebral perfusion pressure, repolarization, and the inhibition of excessive glutamate release, which would prevent ultra-early brain injury following SAH.

Risk factor management matters more than pharmaceutical cyclooxygenase-2 inhibition in the prevention of de novo intracranial aneurysms

BACKGROUND AND PURPOSE

Pathophysiological studies of saccular intracranial aneurysm (sIA) disease have shown that inflammation plays a crucial role in sIA development. Pharmaceutical inhibition of COX-2-PGE2-NF-κB signaling (COX-2, cyclooxygenase-2; PGE2, prostaglandin E2; NF-κB, nuclear factor κB) has been shown in animal models to inhibit sIA formation and progression suggesting that use of medication inhibiting COX-2 could reduce intracranial aneurysm formation also in patients.

METHODS

The impact of COX-2 inhibition on de novo sIA formation was studied in two cohorts: in a previously described angiographically followed cohort of 1419 sIA patients and in a cohort of 117 sIA patients treated with stenting or stent-assisted embolization. Patients were identified from our population-based Kuopio Intracranial Aneurysm Database. Data on the use of anti-inflammatory medications and hospital diagnoses were obtained from national registries. Risk factors were identified by univariate and multivariate analyses.

RESULTS

De novo sIA patients were younger and more often smokers. Use of COX-2 selective inhibitors or nonsteroidal anti-inflammatory drugs did not significantly reduce de novo sIA formation, but the percentage of patients with de novo sIA formation was smaller in patients with prescribed regular acetylsalicylic acid medication (1.1% vs. 3.6%). In the multivariate analysis, however, neither acetylsalicylic acid use nor other type of pharmaceutical inhibition of COX-2 reduced the formation of de novo sIAs. The risk was mostly affected by age, smoking history and irregular usage of antihypertensive medication regardless of used COX-2 inhibition level.

CONCLUSION

For the prevention of de novo sIA formation, risk factor management with focus on cessation of smoking and treating hypertension adequately seems more important than pharmaceutical COX-2 inhibition.

RIPK1 or RIPK3 deletion prevents progressive neuronal cell death and improves memory function after traumatic brain injury

Traumatic brain injury (TBI) causes acute and subacute tissue damage, but is also associated with chronic inflammation and progressive loss of brain tissue months and years after the initial event. The trigger and the subsequent molecular mechanisms causing chronic brain injury after TBI are not well understood. The aim of the current study was therefore to investigate the hypothesis that necroptosis, a form a programmed cell death mediated by the interaction of Receptor Interacting Protein Kinases (RIPK) 1 and 3, is involved in this process. Neuron-specific RIPK1- or RIPK3-deficient mice and their wild-type littermates were subjected to experimental TBI by controlled cortical impact. Posttraumatic brain damage and functional outcome were assessed longitudinally by repetitive magnetic resonance imaging (MRI) and behavioral tests (beam walk, Barnes maze, and tail suspension), respectively, for up to three months after injury. Thereafter, brains were investigated by immunohistochemistry for the necroptotic marker phosphorylated mixed lineage kinase like protein(pMLKL) and activation of astrocytes and microglia. WT mice showed progressive chronic brain damage in cortex and hippocampus and increased levels of pMLKL after TBI. Chronic brain damage occurred almost exclusively in areas with iron deposits and was significantly reduced in RIPK1- or RIPK3-deficient mice by up to 80%. Neuroprotection was accompanied by a reduction of astrocyte and microglia activation and improved memory function. The data of the current study suggest that progressive chronic brain damage and cognitive decline after TBI depend on the expression of RIPK1/3 in neurons. Hence, inhibition of necroptosis signaling may represent a novel therapeutic target for the prevention of chronic post-traumatic brain damage.

Weather conditions associated with subarachnoid hemorrhage: a multicenter case-crossover study

BACKGROUND

Most spontaneous subarachnoid hemorrhages (SAH) occur unexpectedly and independently of classical risk factors. In the light of increasing climate variability and change, we investigated weather and rapid weather changes as possible short-term risk factors for SAH.

METHODS

Seven hundred ninety one patients admitted to three major hospitals in Germany for non-traumatic SAH with a determinable onset of SAH symptoms were included in this hospital-based, case-crossover study. The effects of atmospheric pressure, relative air humidity, and ambient temperature and their 24 h changes on the onset of SAH under temperate climate conditions were estimated.

RESULTS

There was no association between the risk of SAH and 24 h weather changes, mean daily temperature or mean relative air humidity in the overall population. For every 11.5 hPa higher mean daily atmospheric pressure, the risk of SAH increased by 15% (OR 1.15, 95% confidence interval (CI) 1.01-1.30) in the entire study population with a lag time of three days.

CONCLUSION

Our results suggest no relevant association between 24 h-weather changes or absolute values of ambient temperature and relative humidity and the risk of SAH. The medical significance of the statistically weak increase in SAH risk three days after exposure to high atmospheric pressure is unclear. However, as the occurrence of stable high-pressure systems will increase with global warming and potentially affect SAH risk, we call for confirming studies in different geographical regions to verify our observations.

Predictors of Quality of Life at 3 Months after Treatment for Aneurysmal Subarachnoid Hemorrhage

Background

Patients with aneurysmal subarachnoid hemorrhage (SAH) have a low quality of life (QOL) despite diagnostic and therapeutic advancements. Less than half of the survivors can return to their previous jobs and have difficulty in being a functional part of society. Our study aimed to understand the overall outcome and QOL of these patients and to identify the predictive factors determining the same.

Methods

The clinical and radiological data were recorded at presentation, subsequent intervals at the hospital, and during discharge. Patients were interviewed telephonically or in the clinic subsequently at 3 months after treatment with following outcome assessment tools: Modified Rankin Scale (mRS), Barthel Index (BI), QOL after Brain Injury Overall Scale (QOLIBRI-OS), and Short Form 36 (SF 36) QOL scale.

Results

Out of the total patients (n = 143), 124 patients survived, of which 106 patients could be interviewed. The mRS, QOLIBRI-OS, BI, and SF36 had a good correlation with each other. Only 4.7% had moderate to severe disability on the mRS scale, and 2.8% had severe disability according to the Barthel index. Nearly one-third of patients had deteriorated QOL. The mental health domain was worst affected. The major determinant of QOL was GCS at presentation (mean P value 0.01), a course in the ward (0.0001), GCS at discharge (0.001).

Conclusion

Though fewer of the patients had a severe disability, a majority of them had deterioration in QOL.

Correlation of Aneurysmal Wall Enhancement of Unruptured Intracranial Aneurysms on High-Resolution Vessel-Wall Imaging With Clinical Indices and Surgical Findings

BACKGROUND

Many physicians consider aneurysmal wall enhancement (AWE) on high resolution-vessel wall imaging (HR-VWI) as an imaging biomarker of unstable unruptured intracranial aneurysms (UIAs).

OBJECTIVE

To evaluate the clinical value of different AWE signal intensities (SIs) by assessing the correlation between the AWE SIs and surgical findings and rupture risk assessment tools.

METHODS

Twenty-six patients with 34 aneurysms who underwent surgical clipping were included. The corrected AWE SI was calculated by comparing T1-weighted images with post-gadolinium enhanced T1-weighted images. The correlation of AWE with the population, hypertension, age, size of aneurysm, earlier subarachnoid hemorrhage from another aneurysm, site of aneurysm (PHASES) and earlier subarachnoid hemorrhage, location of the aneurysm, age >60 years, population, size of the aneurysm, shape of the aneurysm (ELAPSS) scores was evaluated using correlation and linear regression analysis. To quantify the surgical findings, the average color value of the aneurysms expressed in the CIELCh system was measured. Δh, color difference from yellow, was used for statistical analysis.

RESULTS

The mean age of the patients and aneurysm size were 64.08 yr and 6.95 mm, respectively. The mean AWE SI, PHASES and ELAPSS scores, and Δh were 22.30, 8.41, 20.32, and 41.36, respectively. The coefficients of correlation of AWE SI with the PHASES and ELAPSS scores and Δh were 0.526, 0.563, and -0.431. We found that the AWE SI affected the PHASES (β = 0.430) and ELAPSS scores (β = 0.514) and Δh (β = -0.427) in simple linear regression analysis.

CONCLUSION

The AWE on HR-VWI was correlated with the PHASES and ELAPSS scores and the color. The stronger the AWE, the higher were the PHASES and ELAPSS scores and the more abnormal was the color. The AWE might indicate the degree of inflammation.

Incidental Unruptured Intracranial Aneurysms Do Not Impact Outcome in Patients With Acute Cerebral Infarction

Background: This study was to examine the patients with acute cerebral infarction (ACI) treated at a single center over 9 years and who underwent Unruptured intracranial aneurysm (UIA) screening by three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA), and to explore the factors associated with outcomes.

Methods: The outcome was the modified Rankin scale (mRS) score at 90 days after stroke onset. The outcome was classified into a good outcome (mRS score of 0–2 points) and poor outcome (mRS score of 3–6 points).

Results: UIAs were found in 260 (6.5%) of 4,033 patients with ACI; 2,543 (63.1%) had a good outcome, and 1,490 (36.9%) had a poor outcome. There was no difference in outcomes between the two groups (P = 0.785). The multivariable analysis showed that age (OR = 1.009, 95%CI: 1.003–1.014, P = 0.003), diabetes (OR = 1.179, 95%CI: 1.035–1.342, P = 0.013), ischemic stroke history (OR = 1.451, 95%CI: 1.256–1.677, P < 0.001), and baseline NIHSS score (OR = 1.034, 95%CI: 1.018–1.050, P < 0.001) were independently associated with the 90-day outcomes in patients with ACI. The presence of incidental UIA was not associated with outcomes after ACI.

Conclusions: Age, diabetes, ischemic stroke history, and baseline NIHSS score were independently associated with the early outcomes of patients with ACI.

Development of a patient-reported outcome measure for patients who have recovered from a subarachnoid hemorrhage: the "questionnaire for the screening of symptoms in aneurysmal subarachnoid hemorrhage" (SOS-SAH)

Background

Patients who have been successfully treated for an aneurysmal subarachnoid hemorrhage (aSAH) often retain multiple health complaints, including mood disorders, cognitive complaints, fatigue, and problems with social participation. These problems are not always fully addressed during hospital visits or in current outcome measures, such as the modified Rankin score and the Glasgow Outcome Scale. Here, we present the development of the “Questionnaire for the Screening of Symptoms in aneurysmal Subarachnoid Hemorrhage” (SOS-SAH), which screens for the self-reported symptoms of patients with mild disabilities.

Methods

During the development of the SOS-SAH we adhered to the PROM-cycle framework for the selection and implementation of patient-reported outcome measures (PROMs). The SOS-SAH was developed in an iterative process informed by a literature study. Patients and healthcare professionals were involved in the development process through participating in a working group, interviews, and a cognitive validation study.

Results and conclusions

Relevant patient-reported outcomes (PROs) were identified for patients with aSAH. The SOS-SAH was developed primarily using domains and items from existing PROMs and, if necessary, by developing new items. The SOS-SAH consists of 40 items and covers 14 domains: cognitive abilities, hypersensitivity to stimuli, anxiety, depression, fatigue, social roles, personality change, language, vision, taste, smell, hearing, headache, and sexual function. It also includes a proxy measurement for use by family members to assess cognitive functioning and personality change.

Blockade of Motor Cortical Long-Term Potentiation Induction by Glutamatergic Dysfunction Causes Abnormal Neurobehavior in an Experimental Subarachnoid Hemorrhage Model

Subarachnoid hemorrhage (SAH) is a life-threatening condition that can also lead to permanent paralysis. However, the mechanisms that underlying neurobehavioral deficits after SAH have not been fully elucidated. As theta burst stimulation (TBS) can induce long-term potentiation (LTP) in the motor cortex, we tested its potential as a functional evaluation tool after experimentally induced SAH. Motor cortical inter-neuronal excitability was evaluated in anesthetized rats after 200 Hz-quadripulse TBS (QTS5), 200 Hz-quadripulse stimulation (QPS5), and 400 Hz-octapulse stimulation (OPS2.5). Furthermore, correlation between motor cortical LTP and N-methyl-D-aspartate-receptor activation was evaluated using MK-801, a NMDA-receptor antagonist. We evaluated inhibition-facilitation configurations [interstimulus interval: 3 ms; short-latency intracortical inhibition (SICI) and 11 ms; intracortical facilitation (ICF)] with paired electrical stimulation protocols and the effect of TBS paradigm on continuous recording of motor-evoked potentials (MEPs) for quantitative parameters. SAH and MK-801 completely blocked ICF, while SICI was preserved. QTS5, QPS5, and OPS2.5 facilitated continuous MEPs, persisting for 180 min. Both SAH and MK-801 completely blocked MEP facilitations after QPS5 and OPS2.5, while MEP facilitations after QTS5 were preserved. Significant correlations were found among neurological scores and 3 ms-SICI rates, 11 ms-ICF rates, and MEP facilitation rates after 200 Hz-QTS5, 7 days after SAH (R² = 0.6236; r = −0.79, R² = 0.6053; r = −0.77 and R² = 0.9071; r = 0.95, p < 0.05, respectively). Although these findings need to be verified in humans, our study demonstrates that the neurophysiological parameters 3 ms-SICI, 11 ms-ICF, and 200 Hz-QTS5-MEPs may be useful surrogate quantitative biomarkers for assessing inter-neuronal function after SAH.

Assessment of an Artificial Intelligence Algorithm for Detection of Intracranial Hemorrhage

BACKGROUND

Immediate and accurate detection of intracranial hemorrhages (ICHs) is essential to provide a good clinical outcome for patients with ICH. Artificial intelligence has the potential to provide this, but the assessment of these methods needs to be investigated in depth. This study aimed to assess the ability of Canon's ^AUTOStroke Solution ICH detection algorithm to accurately identify patients both with and without ICHs present.

METHODS

Data from 200 ICH and 102 non-ICH patients who presented with stroke-like symptoms between August 2016 and December 2019 were collected retrospectively. Patients with ICH had at least one of the following hemorrhage types: intraparenchymal (n = 181), intraventricular (n = 45), subdural (n = 13), or subarachnoid (n = 19). Noncontrast computed tomography scans were analyzed for each patient using Canon's ^AUTOStroke Solution ICH algorithm to determine which slices contained hemorrhage. The algorithm's ability to detect ICHs was assessed using sensitivity, specificity, positive predictive value, and negative predictive value. Percentages of cases correctly identified as ICH positive and negative were additionally calculated.

RESULTS

Automated analysis demonstrated the following metrics for identifying hemorrhage slices within all 200 patients with ICH (95% confidence intervals): sensitivity = 0.93 ± 0.03, specificity = 0.93 ± 0.01, positive predictive value = 0.85 ± 0.02, and negative predictive value = 0.98 ± 0.01. A total of 95% (245 of 258) of ICH volumes were correctly triaged, whereas 88.2% (90 of 102) of non-ICH cases were correctly classified as ICH negative.

CONCLUSIONS

Canon's ^AUTOStroke Solution ICH detection algorithm was able to accurately detect intraparenchymal, intraventricular, subdural, and subarachnoid hemorrhages in addition to accurately determine when an ICH was not present. Having this automated ICH detection method could drastically improve treatment times for patients with ICH.

Automated Quantification of Reduced Sulcal Volume Identifies Early Brain Injury After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Early brain injury may be a more significant contributor to poor outcome after aneurysmal subarachnoid hemorrhage (aSAH) than vasospasm and delayed cerebral ischemia. However, studying this process has been hampered by lack of a means of quantifying the spectrum of injury. Global cerebral edema (GCE) is the most widely accepted manifestation of early brain injury but is currently assessed only through subjective, qualitative or semi-quantitative means. Selective sulcal volume (SSV), the CSF volume above the lateral ventricles, has been proposed as a quantitative biomarker of GCE, but is time-consuming to measure manually. Here we implement an automated algorithm to extract SSV and evaluate the age-dependent relationship of reduced SSV on early outcomes after aSAH.

METHODS

We selected all adults with aSAH admitted to a single institution with imaging within 72 hours of ictus. Scans were assessed for qualitative presence of GCE. SSV was automatically segmented from serial CTs using a deep learning-based approach. Early SSV was the lowest SSV from all early scans. Modified Rankin Scale score of 4 to 6 at hospital discharge was classified as a poor outcome.

RESULTS

Two hundred forty-four patients with aSAH were included. Sixty-five (27%) had GCE on admission while 24 developed it subsequently within 72 hours. Median SSV on admission was 10.7 mL but frequently decreased, with minimum early SSV being 3.0 mL (interquartile range, 0.3-11.9). Early SSV below 5 mL was highly predictive of qualitative GCE (area under receiver-operating-characteristic curve, 0.90). Reduced early SSV was an independent predictor of poor outcome, with a stronger effect in younger patients.

CONCLUSIONS

Automated assessment of SSV provides an objective biomarker of GCE that can be leveraged to quantify early brain injury and dissect its impact on outcomes after aSAH. Such quantitative analysis suggests that GCE may be more impactful to younger patients with SAH.

Polymorphisms in Lysyl Oxidase Family Genes Are Associated With Intracranial Aneurysm Susceptibility in a Chinese Population

PURPOSE

Intracranial aneurysms (IA) comprise a multifactorial disease with unclear physiological mechanisms. The lysyl oxidase (LOX) family genes (LOX, LOX-like 1-4) plays important roles in extracellular matrix (ECM) reconstruction and has been investigated in terms of susceptibility to IA in a few populations. We aimed to determine whether polymorphisms in LOX family genes are associated with susceptibility to IA in a Chinese population.

METHODS

This case-control study included 384 patients with IA and 384 healthy individuals without IA (controls). We genotyped 27 single nucleotide polymorphisms (SNPs) of LOX family genes using the Sequenom MassARRAY^® platform. These SNPs were adjusted for known risk factors and then, odds ratios (OR) and 95% confidence intervals (CI) were evaluated using binary logistic regression analysis.

RESULTS

The result showed that LOX rs10519694 was associated with the risk of IA in recessive (OR, 3.88; 95% CI, 1.12-13.47) and additive (OR, 1.56; 95%CI, 1.05-2.34) models. Stratified analyses illustrated that LOX rs10519694 was associated with the risk of single IA in the recessive (OR, 3.95; 95%CI, 1.04-15.11) and additive (OR, 1.64; 95%CI, 1.04-2.56) models. The LOXL2 rs1010156 polymorphism was associated with multiple IA in the dominant model (OR, 1.92; 95%CI, 1.02-3.62). No associations were observed between SNPs of LOXL1, LOXL3, and LOXL4 and risk of IA.

CONCLUSION

LOX and LOXL2 polymorphisms were associated with risk of single IA and multiple IA in a Chinese population, suggesting potential roles of these genes in IA. The effects of these genes on IA require further investigation.

Cognitive function and health-related quality of life 1 year after acute brain injury: An observational study

BACKGROUND

Cognitive impairment and reduced health-related quality of life (HRQoL) are well-established sequelae of critical illness. Studies on survivors of critical illness have found delirium to be a predictor of these conditions, but evidence regarding survivors of acute brain injury is sparse. We aimed to explore if delirium duration was associated with 1-year cognitive impairment and reduced HRQoL in patients with acute brain injury.

METHOD

Intensive care unit (ICU) delirium was assessed using the Intensive Care Delirium Screening Checklist. Cognitive status was assessed using the Repeatable Battery for Neuropsychological Status (RBANS) and HRQoL using the European Quality of Life 5-dimension questionnaire (EQ-5D). We used a multiple linear regression for testing the association of delirium duration with cognitive impairment and quality of life, respectively.

RESULTS

Forty-seven survivors of acute brain injury participated in follow-up and 35 completed RBANS. Delirium was present in 39 of 47 (83%) with a median duration of 4 days. Delirium duration did not predict cognitive impairment (95% CI -4.1 to 0.5) or lower HRQoL (95% CI -1.4 to 2.7). Moderate-to-severe cognitive impairment was present in 17 of 35 (49%) participants, and they had a mean EQ-5D health visual analogue scale of 70.9 vs 81.6 for the Danish age-matched norm.

CONCLUSIONS

Our sample did not demonstrate an association between delirium and 1-year cognitive impairment or reduced HRQoL. Still, a large proportion of the participants were cognitively impaired, and their quality of life was lower compared to norm. Larger studies are necessary to explore these associations further.

Aneurysmal Subarachnoid Hemorrhage: the Last Decade

Aneurysmal subarachnoid hemorrhage (SAH) affects six to nine people per 100,000 per year, has a 35% mortality, and leaves many with lasting disabilities, often related to cognitive dysfunction. Clinical decision rules and more sensitive computed tomography (CT) have made the diagnosis of SAH easier, but physicians must maintain a high index of suspicion. The management of these patients is based on a limited number of randomized clinical trials (RCTs). Early repair of the ruptured aneurysm by endovascular coiling or neurosurgical clipping is essential, and coiling is superior to clipping in cases amenable to both treatments. Aneurysm repair prevents rebleeding, leaving the most important prognostic factors for outcome early brain injury from the hemorrhage, which is reflected in the neurologic condition of the patient, and delayed cerebral ischemia (DCI). Observational studies suggest outcomes are better when patients are managed in specialized neurologic intensive care units with inter- or multidisciplinary clinical groups. Medical management aims to minimize early brain injury, cerebral edema, hydrocephalus, increased intracranial pressure (ICP), and medical complications. Management then focuses on preventing, detecting, and treating DCI. Nimodipine is the only pharmacologic treatment that is approved for SAH in most countries, as no other intervention has demonstrated efficacy. In fact, much of SAH management is derived from studies in other patient populations. Therefore, further study of complications, including DCI and other medical complications, is needed to optimize outcomes for this fragile patient population.

Six-month mortality and functional outcomes in aneurysmal sub-arachnoid haemorrhage patients admitted to intensive care units in Australia and New Zealand: A prospective cohort study

Historical studies suggest survivors of aneurysmal sub-arachnoid haemorrhage (SAH) have at least a moderate burden of functional impairment. However, there is a paucity of modern data concerning these outcomes in those admitted to the intensive care unit (ICU). Accordingly, the aim of this multicentre prospective observational cohort study was to provide contemporary epidemiological data concerning 6-month outcomes of adult aneurysmal SAH patients admitted to ICU in Australia and New Zealand (ANZ). Between March 2016 and June 2018 (inclusive), 357 patients requiring ICU admission were enrolled into the study, from eleven (n = 11) neurosurgical centres in ANZ. The majority of patients were female (n = 242, 68%), the median [IQR] age was 57 [49, 67] years, and almost all were living independently prior to their SAH (n = 337, 94%). 38% (n = 134) suffered a high-grade (WFNS 4-5) SAH. The median index ICU and hospital lengths of stay (LOS) were 9 [4-14], and 20 [13-29] days, respectively. In-hospital mortality was 22% (n = 77). Of the evaluable cohort (n = 348), a further nine (n = 9) patients had died by 6-months, yielding an all cause mortality of 25% (n = 86). Moreover, 35% (n = 114) of assessable patients were 'dead or disabled' (modified Rankin scale ≥4) at 6-months, and there was significant variation between sites, independent of SAH severity. Overall, these patients consumed substantial healthcare resources, and given the burden of mortality and morbidity, in addition to the variability between institutions, there may be opportunity to improve patient outcomes.

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.

A Direct Correlation between Red Blood Cell Indices and Cognitive Impairment After Aneurysmal Subarachnoid Hemorrhage (aSAH)

BACKGROUND

Cognitive impairment can occur after aneurysmal subarachnoid hemorrhage (aSAH) though it commonly tends to be neglected. Red blood cell (RBC) indices are associated with long-term functional outcomes, while it is unclear whether RBC indices could be a potential predictor of cognitive decline after aSAH. We aimed to investigate the association between RBC indices and post-aSAH cognitive impairment at 1 year.

METHODS

Patients with aSAH received neuropsychological test by the Montreal Cognitive Assessment (MoCA) and underwent serum and cerebrospinal fluid (CSF) samples test. To determine the association between RBC indices and cognitive impairment after acute aSAH, we adjusted for demographic and vascular risk factors using multivariate logistic regression analysis.

RESULTS

Of the 126 patients included in this study, 33% (42/126) of them were diagnosed with cognitive impairment (MoCA＜26). After adjustment for potential confounders, increased mean corpuscular volume (MCV) (OR: 1.36, 95%CI: 1.19-1.55) and mean corpuscular hemoglobin (MCH) (OR: 1.61, 95%CI: 1.25-2.08), reflecting systemic iron status, are more likely to be associated with cognitive impairment after aSAH.

CONCLUSION

In this aSAH population, our data shows the positive association between MCH and MCV and cognitive impairment at 1 year.

Exome sequencing study revealed novel susceptibility loci in subarachnoid hemorrhage (SAH)

Aim

To expand our current understanding of the genetic basis of subarachnoid hemorrhage (SAH), and reveal the susceptibility genes in SAH risk.

Methods

We conducted whole-exome sequencing (WES) in a cohort of 196 individuals, including 94 SAH patients and 94 controls, as well as 8 samples that belong to two pedigrees. Systematically examination for rare variations (through direct genotyping) and common variations (through genotyping and imputation) for SAHs were performed in this study.

Results

A total of 16,029 single-nucleotide polymorphisms (SNPs) and 108,999 short indels were detected in all samples, and among them, 30 SNPs distributed on 17 genes presented a strong association signal with SAH. Two novel pathogenic gene variants were identified as associated risk loci, including mutation in TPO and PALD1. The statistical analysis for rare, damaging variations in SAHs identified several susceptibility genes which were involved in degradation of the extracellular matrix and transcription factor signal pathways. And 25 putative pathogenic genes for SAH were also identified basic on functional interaction network analysis with the published SAH-associated genes. Additionally, pedigree analysis revealed autosomal dominant inheritance of pathogenic genes.

Conclusion

Systematical analysis revealed a key role for rare variations in SAH risk and discovered SNPs in new complex loci. Our study expanded the list of candidate genes associated with SAH risk, and will facilitate the investigation of disease-related mechanisms and potential clinical therapies.

Effect of treatment modality and cerebral vasospasm agent on patient outcomes after aneurysmal subarachnoid hemorrhage in the elderly aged 75 years and older

Objective

We sought to examine whether the effect of treatment modality and drugs for cerebral vasospasm on clinical outcomes differs between elderly and non-elderly subarachnoid hemorrhage (SAH) patients in Japan.

Methods

We analyzed the J-ASPECT Study Diagnosis Procedure Combination database (n = 17,343) that underwent clipping or coiling between 2010 and 2014 in 579 hospitals. We stratified patients into two groups according to their age (elderly [≥75 years old], n = 3,885; non-elderly, n = 13,458). We analyzed the effect of treatment modality and anti-vasospasm agents (fasudil hydrochloride, ozagrel sodium, cilostazol, statin, eicosapentaenoic acid [EPA], and edaravone) on in-hospital poor outcomes (mRS 3–6 at discharge) and mortality using multivariable analysis.

Results

The elderly patients were more likely to be female, have impaired levels of consciousness and comorbidity, and less likely to be treated with clipping and anti-vasospasm agents, except for ozagrel sodium and statin. In-hospital mortality and poor outcomes were higher in the elderly (15.8% vs. 8.5%, 71.7% vs. 36.5%).

Coiling was associated with higher mortality (odds ratio 1.43, 95% confidence interval 1.2–1.7) despite a lower proportion of poor outcomes (0.84, 0.75–0.94) in the non-elderly, in contrast to no effect on clinical outcomes in the elderly.

A comparable effect of anti-vasospasm agents on mortality was observed between non-elderly and elderly for fasudil hydrochloride (non-elderly: 0.20, 0.17–0.24), statin (0.63, 0.50–0.79), ozagrel sodium (0.72, 0.60–0.86), and cilostazol (0.63, 0.51–0.77). Poor outcomes were inversely associated with fasudil hydrochloride (0.59, 0.51–0.68), statin (0.84, 0.75–0.94), and EPA (0.83, 0.72–0.94) use in the non-elderly. No effect of these agents on poor outcomes was observed in the elderly.

Conclusions

In contrast to the non-elderly, no effect of treatment modality on clinical outcomes were observed in the elderly. A comparable effect of anti-vasospasm agents was observed on mortality, but not on functional outcomes, between the non-elderly and elderly.

The Impact of Resilience Factors and Anxiety During Hospital Admission on Longitudinal Anxiety Among Dyads of Neurocritical Care Patients Without Major Cognitive Impairment and Their Family Caregivers

BACKGROUND/OBJECTIVE

Anxiety is common in patients experiencing neurocritical illness and their family caregivers. Resilience factors like mindfulness and coping skills may be protective against symptoms of emotional distress, including anxiety. Less is known about the interplay of anxiety symptoms and resilience factors between patients and caregivers. The purpose of this study is to examine the trajectory of anxiety symptoms among dyads of neurocritical care patients without major cognitive impairment and their family caregivers and to elucidate the relationship between resiliency (e.g., mindfulness and coping) and anxiety in these dyads.

METHODS

Prospective, longitudinal study of adults admitted to the neurological intensive care unit (Neuro-ICU) and their caregivers. Dyads of patients (N = 102) and family caregivers (N = 103) completed self-report measures of mindfulness (Cognitive Affective Mindfulness Scale-Revised) and coping (Measure of Current Status-Part A) during Neuro-ICU hospitalization and anxiety symptoms (anxiety subscale of the Hospital Anxiety and Depression Scale) during hospitalization and at 3- and 6-month follow-up. We used actor-partner interdependence modeling to predict the effect of one's own baseline characteristics on one's own and one's partner's future anxiety symptoms.

RESULTS

Rates of clinically significant anxiety symptoms were 40% for patients and 42% for caregivers at baseline. Of these, 20% of patients and 23% of caregivers showed moderate and severe symptoms. Approximately, one-third of patients and caregivers reported clinically significant anxiety symptoms at 3- and 6-month follow-ups, with more than 20% endorsing moderate or severe symptoms. Patients' own baseline mindfulness, coping, and anxiety symptoms were associated with lower anxiety symptoms at all time points (ps < 0.001)-this was also true for caregivers. For both patients and caregivers, one's own baseline mindfulness predicted their partner's anxiety symptoms 3 months later (p = 0.008), but not at 6-month follow-up.

CONCLUSIONS

Anxiety symptoms in Neuro-ICU patient-caregiver dyads are high through 6 months following admission. Mindfulness is interdependent and protective against anxiety in dyads at 3-month but not 6-month follow-up. Early, dyad-based interventions may prevent the development of chronic anxiety in patients without major cognitive impairment and caregivers.

High-normal PaCO2 values might be associated with worse outcome in patients with subarachnoid hemorrhage - a retrospective cohort study

BACKGROUND

While both hypercapnia and hypocapnia are harmful in patients with subarachnoid hemorrhage (SAH), it is unknown whether high-normal P_aCO₂ values are better than low-normal values. We hypothesized that high-normal P_aCO₂ values have more detrimental than beneficial effects on outcome.

METHODS

Consecutive patients with aneurysmal subarachnoid hemorrhage (aSAH) requiring mechanical ventilation treated in a tertiary care university hospital were retrospectively analyzed regarding the influence of P_aCO₂ on favorable outcome, defined as modified Rankin scale score < 3 at discharge. Primary endpoint was the difference in the proportion of P_aCO₂ values above 40 mmHg in relation to all measured P_aCO₂ values between patients with favorable and unfavorable outcome.

RESULTS

150 patients were included. Median age was 57 years (p25:50, p75:64), median Hunt-Hess score was 4 (p25:3, p75:5). P_aCO₂ values were mainly within normal range (median 39.0, p25:37.5, p75:41.4). Patients with favorable outcome had a lower proportion of high-normal P_aCO₂ values above 40 mmHg compared to patients with unfavorable outcome (0.21 (p25:0.13, p75:0.50) vs. 0.4 (p25:0.29, p75:0.59)) resulting in a lower chance for favorable outcome (OR 0.04, 95% CI 0.00-0.55, p = 0.017). In multivariable analysis adjusted for Hunt-Hess score, pneumonia and length of stay, elevated P_aCO₂ remained an independent predictor of outcome (OR 0.05, 95% CI 0.00-0.81, p = 0.035).

CONCLUSIONS

A higher proportion of P_aCO₂ values above 40 mmHg was an independent predictor of outcome in patients with aSAH in our study. The results need to be confirmed in a prospective trial.

Role of bioclimate conditions on cerebral aneurysm rupture in the Brittany region of France

INTRODUCTION

Subarachnoid hemorrhage (SAH) from intracranial aneurysm rupture is an unpredictable event responsible for significant morbidity and mortality. Despite inconsistencies, some studies suggest a potential role of climate conditions in SAH onset. The purpose of this study was to determine the impact of climatic and lunar factors on onset of SAH in an oceanic climate such as that of Brittany, France.

METHODS

All adults with SAH admitted to the neurosurgery department and intensive care unit of the University Hospital of Rennes (France) between January 1st, 2011 and December 31st, 2012 were included. Meteorological variables, their variations, lunar phases and tidal coefficients were compared between days with and without SAH.

RESULTS

We retrospectively included 295 patients with SAH. Mean minimum temperature was significantly lower during days with SAH (7.7±4.7°C versus 8.3±4.6°C; P=0.039); temperature variation between 2 successive days was significantly greater for days with SAH (8.6±4.1°C versus 7.9±3.8°C; P<0.01). Multivariate analysis showed that a 2-day temperature drop greater than or equal to 8°C was associated with 35% increased risk of SAH (odds ratio 1.35 [1.03-1.77]). There were no significant effects of other meteorological variables, lunar phase or tidal coefficient on SAH occurrence.

CONCLUSION

Low temperature and sudden temperature drop were associated with increased occurrence of SAH in Brittany, France.

Symptoms and consequences of subarachnoid haemorrhage after 7 years

Objectives

Short‐term follow‐up studies after a subarachnoid haemorrhage (SAH) have shown impaired cognition, fatigue, depression and anxiety, but less is known regarding long‐term consequences. The aim of this study was to investigate health outcomes in persons 7 years after SAH.

Materials and Methods

This is a descriptive cohort follow‐up study of persons with non‐traumatic SAH treated at Sahlgrenska University Hospital, Gothenburg, Sweden. The follow‐up was conducted 7 years post‐treatment and included home visits using forms and questionnaires about health outcomes; the Barthel Index (BI), modified Rankin Scale (mRS), National Institutes of Health Stroke Scale (NIHSS), Hospital Anxiety and Depression Scale (HADS), Montreal Cognitive Assessment (MoCA) and Multidimensional Fatigue Inventory (MFI).

Results

Seven years post‐SAH, 33 persons fulfilled the inclusion criteria, of whom 18 (55%) participated (median age 63 years). Cognitive impairment was present in 11 participants, assessed with the MoCA, where the item of delayed recall was most difficult. The majority (n = 16) were independent in activities of daily living (ADL), and few (n = 3) had physical symptoms according to the NIHSS. However, three participants were free from disability according to the mRS. Nearly, half of the participants had symptoms of anxiety (n = 8). Three had symptoms of depression and more than half experienced fatigue.

Conclusion

The physical function and independency in ADL is high among long‐term SAH survivors. Despite this, only a few were completely free from disability, and the main problems 7 years after SAH were cognitive impairment and anxiety.

Characteristics of Unruptured Compared to Ruptured Intracranial Aneurysms: A Multicenter Case-Control Study

BACKGROUND

Only a minority of intracranial aneurysms rupture to cause subarachnoid hemorrhage.

OBJECTIVE

To test the hypothesis that unruptured aneurysms have different characteristics and risk factor profiles compared to ruptured aneurysms.

METHODS

We recruited patients with unruptured aneurysms or aneurysmal subarachnoid hemorrhages at 22 UK hospitals between 2011 and 2014. Demographic, clinical, and imaging data were collected using standardized case report forms. We compared risk factors using multivariable logistic regression.

RESULTS

A total of 2334 patients (1729 with aneurysmal subarachnoid hemorrhage, 605 with unruptured aneurysms) were included (mean age 54.22 yr). In multivariable analyses, the following variables were independently associated with rupture status: black ethnicity (odds ratio [OR] 2.42; 95% confidence interval [CI] 1.29-4.56, compared to white) and aneurysm location (anterior cerebral artery/anterior communicating artery [OR 3.21; 95% CI 2.34-4.40], posterior communicating artery [OR 3.92; 95% CI 2.67-5.74], or posterior circulation [OR 3.12; 95% CI 2.08-4.70], compared to middle cerebral artery). The following variables were inversely associated with rupture status: antihypertensive medication (OR 0.65; 95% CI 0.49-0.84), hypercholesterolemia (0.64 OR; 95% CI 0.48-0.85), aspirin use (OR 0.28; 95% CI 0.20-0.40), internal carotid artery location (OR 0.53; 95% CI 0.38-0.75), and aneurysm size (per mm increase; OR 0.76; 95% CI 0.69-0.84).

CONCLUSION

We show substantial differences in patient and aneurysm characteristics between ruptured and unruptured aneurysms. These findings support the hypothesis that different pathological mechanisms are involved in the formation of ruptured aneurysms and incidentally detected unruptured aneurysms. The potential protective effect of aspirin might justify randomized prevention trials in patients with unruptured aneurysms.

Mesenchymal stem cells for hemorrhagic stroke: status of preclinical and clinical research

Significant progress has been made during the past few decades in stem cell therapy research for various diseases and injury states; however this has not been overwhelmingly translated into approved therapies, despite much public attention and the rise in unregulated ‘regenerative clinics’. In the last decade, preclinical research focusing on mesenchymal stem/stromal cell (MSC) therapy in experimental animal models of hemorrhagic stroke has gained momentum and has led to the development of a small number of human trials. Here we review the current studies focusing on MSC therapy for hemorrhagic stroke in an effort to summarize the status of preclinical and clinical research. Preliminary evidence indicates that MSCs are both safe and tolerable in patients, however future randomized controlled trials are required to translate the promising preclinical research into an effective therapy for hopeful patients.

Patient-reported outcome measures in subarachnoid hemorrhage: A systematic review

OBJECTIVE

Patient-reported outcomes (PROs) are aspects of a patient's health status and are considered important for stimulating patient-centered care. Current outcome measures in clinical care for patients with aneurysmal subarachnoid hemorrhage (aSAH) are insufficient to capture PROs. In this systematic review, we aimed to summarize the evidence regarding the quality of patient-reported outcome measures (PROMs) in aSAH patients.

METHODS

We performed a systematic review of the literature published from inception until October 29, 2018, in PubMed, the Cochrane Central Register of Controlled Trials, and EMBASE. Eligible studies had to evaluate measurement properties and capture PROs in aSAH patients. The quality of the studies and measurement properties were assessed using the consensus-based standards for the selection of health status measurement instruments (COSMIN) checklist. The review protocol was registered with PROSPERO (CRD42018058566).

RESULTS

We identified 9 articles that reported the assessment of 7 different disease-specific and generic PROMs used for aSAH patients, including 5 that focused on the Stroke-Specific Quality of Life Scale (SS-QoL). The methodologic quality of the validation processes used was generally doubtful. None of the PROMs complied with current standards for content validity.

CONCLUSIONS

Due to the low quality of evidence for the measurement properties, the evidence base for selecting a suitable PROM for use with aSAH patients is insufficient. Given the specific long-term consequences of aSAH, we consider a disease-specific PROM the most appropriate, with SS-QoL the most suitable PROM currently available.

Admission neutrophil–lymphocyte ratio predicts delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage

Background

Delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH) has a multifactorial pathophysiology, with immune dysregulation being an important component. The neutrophil–lymphocyte ratio (NLR) is an established prognostic marker in patients with cancer, cardiac disease, and sepsis.

Objective

To determine whether there is a relationship between NLR and DCI in patients with aSAH.

Methods

We evaluated 1067 patients with aSAH between 2006 and 2015 enrolled in a single-center, prospective, observational cohort study. Admission white blood cell differentials (NLR) were analyzed using a cut-off point of ≥5.9. DCI from cerebral vasospasm was defined as the occurrence of focal neurological impairment, or a decrease in at least two points on the Glasgow Coma Scale, which was not apparent immediately after aneurysm occlusion, and could not be attributed to other causes. Cerebral infarct was defined as a new infarct on CT that was not visible on the admission or immediate postoperative scan, when the cause was thought to be vasospasm by the research team. Logistic regression models were generated.

Results

We found that 768 (72%) patients had an admission NLR ≥5.9. In a multivariable model, elevated NLR was associated with poor admission Hunt-Hess grade (OR=1.6, 95% CI 1.2 to 2.6, p=0.005), Caucasian ethnicity (OR=2.6, 95% CI 1.9 to 3.7, p<0.001), anterior aneurysm location (OR=1.7, 95% CI 1.2 to 2.4, p=0.004), loss of consciousness at ictus (OR=1.4, 95% CI 1.0 to 2.0, p=0.055), and thick SAH (modified Fisher grade ≥3) (OR=1.8, 95% CI 1.3 to 2.4, p<0.001). Admission NLR predicted development of delayed cerebral ischemia (DCI) (OR=1.7; 95% CI 1.1 to 2.5, p=0.008) after controlling for known predictors such as age, poor admission clinical grade, thick SAH blood, and elevated admission mean arterial pressure.

Conclusions

This study provides further evidence of the association between inflammation and DCI. Admission NLR is a readily available and convenient biomarker that may be a clinically useful tool for prognostication when evaluating aSAH.

Quantitative EEG After Subarachnoid Hemorrhage Predicts Long-Term Functional Outcome

PURPOSE

Delayed cerebral ischemia is a major complication after subarachnoid hemorrhage. Our previous study showed that alpha power reduction in continuous quantitative EEG predicts delayed cerebral ischemia. In this prospective cohort, we aimed to determine the prognostic value of alpha power in quantitative EEG for the long-term outcome of patients with subarachnoid hemorrhage.

METHODS

Adult patients with nontraumatic subarachnoid hemorrhage were included if admitted early enough for EEG to start within 72 hours after symptom onset. Continuous six-channel EEG was applied. Unselected EEG signals underwent automated artifact rejection, power spectral analysis, and detrending. Alpha power decline of ≥40% for ≥5 hours was defined as critical EEG event based on previous findings. Six-month outcome was obtained using the modified Rankin scale.

RESULTS

Twenty-two patients were included (14 male; mean age, 59 years; Hunt and Hess grade I-IV; duration of EEG monitoring, median 14 days). Poor outcome (modified Rankin scale, 2-5) was noted in 11 of 16 patients (69%) with critical EEG events. All six patients (100%) without EEG events achieved an excellent outcome (modified Rankin scale 0, 1) (P = 0.0062; sensitivity 100%, specificity 54.5%). Vasospasm detected with transcranial Doppler/Duplex sonography appeared 1.5 days after EEG events and showed weaker association with outcome (P = 0.035; sensitivity 100%, specificity 45.5%). There was no significant association between EEG events and ischemic lesions on imaging (P = 0.1). Also, no association between ischemic lesions and outcome was seen (P = 0.64).

CONCLUSIONS

Stable alpha power in quantitative EEG reflects successful therapy and predicts good functional outcome after subarachnoid hemorrhage. Critical alpha power reduction indicates an increased risk of poor functional outcome.

Computed tomography perfusion as a predictor of delayed cerebral ischemia and functional outcome in spontaneous subarachnoid hemorrhage: A single center experience

BACKGROUND

Computed tomography (CT) perfusion has been studied as a tool to predict delayed cerebral ischemia (DCI) and clinical outcome in spontaneous subarachnoid hemorrhage (SAH). The purpose of the study was to determine whether quantitative CT perfusion performed within 72 hours after admission can predict the occurrence of DCI and clinical outcome as measured with a modified Rankin scale (mRS) at 3 months after ictus.

METHODS

Cerebral perfusion was assessed in a prospective cohort of patients with acute SAH. CT perfusion parameters at <72 h post SAH were quantitatively measured in the main vascular territories and represented as whole-brain means. Spearman rank correlation coefficient and generalized additive regression models for binary outcome were used.

RESULTS

A total of 66 patients underwent CT perfusion at <72 h. Poor clinical grade on admission was correlated with worse cerebral perfusion in all parameters. Multivariable analysis yielded an association of time to peak (TTP; odds ratio (OR) = 0.89; 95% confidence interval (CI): 0.77, 1.02; p = 0.083) with the occurrence of DCI. We also found an association of TTP values with poor outcome, with an 8% increase in the odds of mRS > 3 for each one second increase in TTP at admission (OR = 1.08; 95% CI: 1.00, 1.17; p = 0.061).

CONCLUSIONS

We identified an association of early TTP changes with DCI and poor clinical outcome. However, there were no associations with cerebral blood flow or mean transit time and DCI/clinical outcome. CT perfusion still remains to be validated as a tool in predicting outcome in SAH.

Thirty-day readmissions in aneurysmal subarachnoid hemorrhage: A good metric for hospital quality?

Thirty-day readmission rates has been increasingly used by clinicians, hospital administrators, and policy makers as a metric for the quality of care. However, the 30-day readmission rates may be affected by other factors intrinsic to the patient and may not be a good measure of the quality of care provided by the hospital. In this review, we examined the quality of the 30-day readmissions rate as a quality metric for the quality of care provided to patients with aneurysmal subarachnoid hemorrhage (SAH). It has been shown that in this patient population, 30-day readmission rate primarily captures values, such as the number of comorbidities, disease severity, and discharge dispositions. There is little association between SAH 30-day readmission rates and mortality. However, 30-day readmissions may be reduced by increasing early discharge surveillance, providing readmission reduction programs to patients discharged to medical facilities as well as to home, and identifying patients most at risk for readmission.

Imaging predictors of outcome in acute spontaneous subarachnoid hemorrhage: a review of the literature

Spontaneous subarachnoid hemorrhage (SAH) accounts for about 5% of strokes, but has a very high morbidity and mortality. Many survivors are left with important cognitive impairment and are severely incapacitated. Prediction of complications such as vasospasm and delayed cerebral ischemia, and of clinical outcome after SAH, is challenging. Imaging studies are essential in the initial evaluation of SAH patients and are increasingly relevant in assessing for complications and prognosis. In this article, we reviewed the role of imaging studies in evaluating early brain injury and predicting complications as well as clinical and neuropsychological prognosis after acute SAH.

Matrix metalloproteinase-9 gene polymorphisms and their interaction with environment on subarachnoid hemorrhage risk

The current study aimed to investigate the relations of three single nucleotide polymorphisms of matrix metalloproteinase-9 gene, and single nucleotide polymorphisms-smoking interaction to subarachnoid hemorrhage risk. The optimal pattern of the interaction among single nucleotide polymorphisms and smoking was selected by generalized multifactor dimensionality reduction. The association between the three single nucleotide polymorphisms within the matrix metalloproteinase-9 gene was analyzed by logistic regression test. As well as genetic risk of subarachnoid hemorrhage interactions with smoking, the risk of subarachnoid hemorrhage in carriers with the rs3918242 (T) was significantly higher than in carriers carrying CC (genotype: CT + TT vs. CC), adjusted OR (95% CI) = 1.58 (1.25-2.03), and in carriers carrying rs17576- (genotype: AG + GG vs. AA), adjust OR (95% CI) = 1.62 (1.19-2.13). However, after adjusting for covariates, we did not find any direct association between rs17577 and subarachnoid hemorrhage risk. The generalized multifactor dimensionality reduction model shows a potential relation between rs3918242 and smoking risk for subarachnoid hemorrhage ( P = 0.0010). After covariates adjustment, current smokers with rs3918242-CT or TT genotype, compared to never-smokers with rs3918242-CC genotype, OR (95% CI) = 2.57 (1.74-3.46), have a higher subarachnoid hemorrhage risk. Our study showed that the rs3918242 (T) and rs17576 (G), the cross reaction between rs3918242 and smoking increased the risk of subarachnoid hemorrhage. Impact statement Matrix metalloproteinase-9 ( MMP-9) is a possible candidate gene for some diseases, including metabolic syndrome, stroke, coronary artery disease (CAD). But to date, limited data focused on the relationship between MMP-9 gene SNPs and SAH susceptibility. The purpose of this study was to evaluate SNPs of MMP-9 gene and their interaction with environmental factors with SAH risk based on a Chinese population.

Prospective study: Long-term outcome at 12-15 years after aneurysmal subarachnoid hemorrhage

BACKGROUND

Patients with aneurysmal subarachnoid hemorrhage (aSAH) have poor outcome. Studies on outcome beyond 1 year post-aSAH are few, and late recovery is poorly investigated, initiating this prospective outcome study on patients 12-15 years after an aSAH. We hypothesized to find; functional improvement > 1 year post-ictus; increased long-term mortality in aSAH patients vs matched controls, and finally to present; predictors of long-term favorable outcome (GOS 4-5).

METHODS

We prospectively investigated patients, admitted 2000-2003 to the Sahlgrenska University Hospital, 1 year post-ictus using Glasgow Outcome Scale (GOS). The patients were revalidated 12-15 years post-aSAH by structured-telephone interviews (GOS), followed by statistical analysis.

RESULTS

A total of 158 patients were included, (women n = 114, men n = 44), with a mean age of 55 years at aSAH. Patients treated with surgical clipping had lower mortality. At the follow-up 12-15 years post-aSAH, all 103 survivors (65.2%) were categorized as having; good recovery (39.9%), moderate disability (15.2%), or severe disability (10.1%). Within the patient cohort, 23.6% improved GOS over time. Fifty-five patients died, median at 4 years post-ictus. aSAH patients had 3.5 times increased mortality 12-15 years post-ictus vs matched controls (P < .0001). Patients with favorable outcome at 1 year (67.3%, n = 101) had similar survival probability as control patients. Prognostic indicators of long-term favorable outcome were low age and high GOS at 1-year follow-up, (AUCROC, 0.79).

CONCLUSIONS

Individual functional improvement was found >1 year post-ictus. Patients with favorable outcome at 1 year had similar long-term life expectancy as the general population. Indicators of long-term favorable prognosis were low age at ictus and high GOS at 1-year follow-up.

A Twelve-Week Moderate Exercise Programme Improved Symptoms of Depression, Insomnia, and Verbal Learning in Post-Aneurysmal Subarachnoid Haemorrhage Patients: A Comparison with Meningioma Patients and Healthy Controls

OBJECTIVES

Deficits in psychological functioning, cognitive functioning, and sleep are frequently experienced by individuals who have survived aneurysmal subarachnoid haemorrhage (aSAH). Exercise has been shown to improve these domains; to date, it has never been explored in patients following aSAH. The aim of this exploratory study is to compare the effects of an exercise programme in this population with another patient group, and a group of healthy controls.

METHODS

The present study explored the effects of 12 weeks of moderate aerobic exercise training on 15 aSAH patients, 16 meningioma patients, and 17 healthy controls. Data on symptoms of depression, hypochondria, perceived stress, satisfaction with life, verbal learning and memory, and subjective and objective sleep, were gathered at baseline, following intervention, and at 6-month follow-up.

RESULTS

aSAH patients and meningioma patients had decreased symptoms of depression and insomnia at follow-up. While perceived stress decreased in the meningioma group, in aSAH patients it increased. Total learning performance increased in all three groups.

CONCLUSIONS

An exercise programme had a positive effect on symptoms of depression, insomnia, and verbal learning in patients following aSAH. No positive changes in other domains were observed. This may be due to the cautious approach taken with regard to exercise intensity.