CT perfusion and delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

Emergent Management of Spontaneous Subarachnoid Hemorrhage

OBJECTIVE

Spontaneous subarachnoid hemorrhage (SAH) carries high morbidity and mortality rates, and the emergent management of this disease can make a large impact on patient outcome. The purpose of this article is to provide a pragmatic overview of the emergent management of SAH.

LATEST DEVELOPMENTS

Recent trials have influenced practice around the use of antifibrinolytics, the timing of aneurysm securement, the recognition of cerebral edema and focus on avoiding a lower limit of perfusion, and the detection and prevention of delayed cerebral ischemia. Much of the acute management of SAH can be protocolized, as demonstrated by two updated guidelines published by the American Heart Association/American Stroke Association and the Neurocritical Care Society in 2023. However, the gaps in evidence lead to clinical equipoise in some aspects of critical care management.

ESSENTIAL POINTS

In acute management, there is an urgency to differentiate the etiology of SAH and take key emergent actions including blood pressure management and coagulopathy reversal. The critical care management of SAH is similar to that of other acute brain injuries, with the addition of detecting and treating delayed cerebral ischemia. Strategies for the detection and treatment of delayed cerebral ischemia are limited by disordered consciousness and may be augmented by monitoring and imaging technology.

Perfusion Computed Tomography as a Screening Tool for Pending Delayed Cerebral Ischemia in Comatose Patients After Aneurysmal Subarachnoid Hemorrhage: A Retrospective Cohort Study

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) is frequently complicated by delayed cerebral ischemia (DCI), leading to poor outcomes. Early diagnosis of DCI is crucial for improving survival and outcomes but remains challenging in comatose patients. In this study, we aimed to evaluate computed tomography with angiography and perfusion (P-CT) as a screening modality on postictal days four and eight for impending DCI after aSAH in comatose patients using vasospasm with hypoperfusion (hVS) as a surrogate and DCI-related infarction as an outcome measure. Two objectives were set: (1) to evaluate the screening's ability to accurately risk stratify patients and (2) to assess the validity of P-CT screening.

METHODS

We conducted a retrospective review of the records of comatose patients with aSAH from January 2019 to December 2021 who were monitored with P-CT scans on days four and eight. The event rates of DCI-related infarction, hVS, and endovascular rescue therapy (ERT) were analyzed, and the sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) for DCI were calculated. DCI-related infarction was defined as new secondary cerebral infarction > 48 h < 6 weeks post aSAH not attributable to other causes, and hVS was defined as arterial narrowing with corresponding hypoperfusion on P-CT.

RESULTS

Fifty-six comatose patients were included, and 98 P-CT scans were performed. The incidence of DCI-related infarction was 40%. Screening P-CT on days four and eight found vasospasm in 23% of all patients, including 11% with hVS. A positive hVS on day four or eight revealed a relative risk of 2.4 [95% confidence interval (CI) 1.13-5.11, p = 0.03], sensitivity of 23% (95% CI 8-45, p = 0.03), specificity of 95% (95% CI 36-100, p = 0.03), PPV of 0.83 (95% CI 0.36-1.00, p = 0.03), and NPV of 0.65 (95% CI 0.50-0.78). Six positive P-CT scans led to digital subtraction angiography in five patients, three of whom received ERT. All ERT-intervened patients developed DCI-related infarction.

CONCLUSIONS

P-CT resulted in few interventions and often resulted in late detection of DCI at an irreversible stage. Although a positive P-CT result accurately predicts impending DCI-related infarction, screening on days four and eight alone in comatose patients with aSAH often fails to timely detect impending DCI. Based on our analysis, we cannot recommend P-CT as a screening modality. P-CT is likely best used as a confirmatory test prior to invasive interventions when guided by continuous multimodal monitoring; however, prospective studies with comparison groups are warranted. The need for a reliable continuous screening modality is evident because of the high rate of deterioration and narrow treatment window.

Prediction of delayed cerebral ischemia followed aneurysmal subarachnoid hemorrhage. A machine-learning based study

INTRODUCTION

Delayed Cerebral Ischemia (DCI) is a significant complication following aneurysmal subarachnoid hemorrhage (aSAH) that can lead to poor outcomes. Machine learning techniques have shown promise in predicting DCI and improving risk stratification.

METHODS

In this study, we aimed to develop machine learning models to predict the occurrence of DCI in patients with aSAH. Patient data, including various clinical variables and co-factors, were collected. Six different machine learning models, including logistic regression, multilayer perceptron, decision tree, random forest, gradient boosting machine, and extreme gradient boosting (XGB), were trained and evaluated using performance metrics such as accuracy, area under the curve (AUC), precision, recall, and F1 score.

RESULTS

After data augmentation, the random forest model demonstrated the best performance, with an AUC of 0.85. The multilayer perceptron neural network model achieved an accuracy of 0.93 and an F1 score of 0.85, making it the best performing model. The presence of positive clinical vasospasm was identified as the most important feature for predicting DCI.

CONCLUSIONS

Our study highlights the potential of machine learning models in predicting the occurrence of DCI in patients with aSAH. The multilayer perceptron model showed excellent performance, indicating its utility in risk stratification and clinical decision-making. However, further validation and refinement of the models are necessary to ensure their generalizability and applicability in real-world settings. Machine learning techniques have the potential to enhance patient care and improve outcomes in aSAH, but their implementation should be accompanied by careful evaluation and validation.

A comprehensive review for artificial intelligence on neuroimaging in rehabilitation of ischemic stroke

Stroke is the second leading cause of death worldwide, with ischemic stroke accounting for a significant proportion of morbidity and mortality among stroke patients. Ischemic stroke often causes disability and cognitive impairment in patients, which seriously affects the quality of life of patients. Therefore, how to predict the recovery of patients can provide support for clinical intervention in advance and improve the enthusiasm of patients for rehabilitation treatment. With the popularization of imaging technology, the diagnosis and treatment of ischemic stroke patients are often accompanied by a large number of imaging data. Through machine learning and Deep Learning, information from imaging data can be used more effectively. In this review, we discuss recent advances in neuroimaging, machine learning, and Deep Learning in the rehabilitation of ischemic stroke.

Early and recurrent cerebral vasospasms after aneurysmal subarachnoid hemorrhage: The impact of age

INTRODUCTION

Cerebral vasospasms remain a strong predictor of poor outcome after aneurysmal SAH. The aim of this study was to describe the time course of relevant vasospasms after aneurysmal SAH and to determine the variables associated with early-onset or prolonged and recurrent vasospasms.

PATIENTS AND METHODS

We conducted a retrospective, single-center study of consecutive adult patients with aneurysmal SAH admitted between 2016 and 2022 at our tertiary stroke center. Relevant vasospasms, defined as vessel narrowing detected in DSA in combination with clinical deterioration or new perfusion deficit, were detected according to our in-house algorithm and eventually treated endovascularly. The primary endpoint was the diagnosis of relevant vasospasms. As secondary endpoints, the time from hemorrhage to the onset of vasospasms and the time from the first to the last endovascular intervention were measured.

RESULTS

Of 368 patients with aneurysmal SAH, 135 (41.0%) developed relevant vasospasms. The median time between ictus and detection of vasospasms was 8 days (IQR: 6-10). Patients with early-onset vasospasms were significantly younger (mean 52.7 ± 11.2 years vs 58.7 ± 11.5 years, p = 0.003) and presented more frequently vasospasm-related infarctions at discharge (58.8% vs 38.7%, p = 0.03). In 74 patients (54.8%), recurrent relevant vasospasms were observed despite endovascular treatment. Younger age and early onset were significantly associated with longer duration of relevant vasospasms (both p < 0.05).

DISCUSSION AND CONCLUSION

Younger age was associated with early-onset and longer duration of relevant vasospasms in this study. More frequent clinical and diagnostic follow-up should be considered in this subgroup of patients that are at risk for poor outcomes.

The impact of perfusion computed tomography on the diagnosis and outcome of delayed cerebral ischemia after subarachnoid hemorrhage

BACKGROUND

Delayed cerebral ischemia (DCI) is a preventable cause of poor neurological outcome in aneurysmal subarachnoid hemorrhage (aSAH). Advances in radiological methods, such as cerebral perfusion computed tomography (CTP), could help diagnose DCI earlier and potentially improve outcomes in aSAH. The objective of this study was to assess whether the use of CTP to diagnose DCI early could reduce the risk of infarction related to DCI.

METHODS

Retrospective cohort study of patients in the intensive care unit of Erasme Hospital (Brussels, Belgium) between 2004 and 2021 with aSAH who developed DCI. Patients were classified as: "group 1" - DCI diagnosed based on clinical deterioration or "group 2" - DCI diagnosed using CTP. The primary outcome was the development of infarction unrelated to the initial bleeding or surgery.

RESULTS

211 aSAH patients were diagnosed with DCI during the study period: 139 (66%) in group 1 and 72 (34%) in group 2. In group 1, 109 (78%) patients developed a cerebral infarction, compared to 45 (63%) in group 2 (p = 0.02). The adjusted cumulative incidence of DCI over time was lower in group 2 than in group 1 [hazard ratio 0.65 (95% CI 0.48-0.94); p = 0.02]. The use of CTP to diagnose DCI was not independently associated with mortality or neurological outcome.

CONCLUSIONS

The use of CTP to diagnose DCI might help reduce the risk of developing cerebral infarction after aSAH, although the impact of such an approach on patient outcomes needs to be further demonstrated.

Diagnosis and management of subarachnoid haemorrhage

Aneurysmal subarachnoid haemorrhage (aSAH) presents a challenge to clinicians because of its multisystem effects. Advancements in computed tomography (CT), endovascular treatments, and neurocritical care have contributed to declining mortality rates. The critical care of aSAH prioritises cerebral perfusion, early aneurysm securement, and the prevention of secondary brain injury and systemic complications. Early interventions to mitigate cardiopulmonary complications, dyselectrolytemia and treatment of culprit aneurysm require a multidisciplinary approach. Standardised neurological assessments, transcranial doppler (TCD), and advanced imaging, along with hypertensive and invasive therapies, are vital in reducing delayed cerebral ischemia and poor outcomes. Health care disparities, particularly in the resource allocation for SAH treatment, affect outcomes significantly, with telemedicine and novel technologies proposed to address this health inequalities. This article underscores the necessity for comprehensive multidisciplinary care and the urgent need for large-scale studies to validate standardised treatment protocols for improved SAH outcomes.

Pharmacological Prevention of Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Causes of morbidity and mortality following aneurysmal subarachnoid hemorrhage (aSAH) include early brain injury and delayed neurologic deterioration, which may result from delayed cerebral ischemia (DCI). Complex pathophysiological mechanisms underlie DCI, which often includes angiographic vasospasm (aVSP) of cerebral arteries.

METHODS

Despite the study of many pharmacological therapies for the prevention of DCI in aSAH, nimodipine-a dihydropyridine calcium channel blocker-remains the only drug recommended universally in this patient population. A common theme in the research of preventative therapies is the use of promising drugs that have been shown to reduce the occurrence of aVSP but ultimately did not improve functional outcomes in large, randomized studies. An example of this is the endothelin antagonist clazosentan, although this agent was recently approved in Japan.

RESULTS

The use of the only approved drug, nimodipine, is limited in practice by hypotension. The administration of nimodipine and its counterpart nicardipine by alternative routes, such as intrathecally or formulated as prolonged release implants, continues to be a rational area of study. Additional agents approved in other parts of the world include fasudil and tirilazad.

CONCLUSIONS

We provide a brief overview of agents currently being studied for prevention of aVSP and DCI after aSAH. Future studies may need to identify subpopulations of patients who can benefit from these drugs and perhaps redefine acceptable outcomes to demonstrate impact.

Early brain metabolic disturbances associated with delayed cerebral ischemia in patients with severe subarachnoid hemorrhage

Delayed cerebral ischemia (DCI) is a devastating complication of aneurysmal subarachnoid hemorrhage (ASAH) causing brain infarction and disability. Cerebral microdialysis (CMD) monitoring is a focal technique that may detect DCI-related neurochemical changes as an advance warning. We conducted retrospective analyses from 44 poor-grade ASAH patients and analyzed glucose, lactate, pyruvate, and glutamate concentrations in control patients without DCI (n = 19), and in patients with DCI whose CMD probe was located within (n = 17) or outside (n = 8) a new infarct. When monitored from within a lesion, DCI was preceded by a decrease in glucose and a surge in glutamate, accompanied by increases in lactate/pyruvate and lactate/glucose ratios whereas these parameters remained stable in control patients. When CMD monitoring was performed outside the lesion, the glutamate surge was absent, but glucose and L/G ratio were still significantly altered. Overall, glucose and L/G ratio were significant biomarkers of DCI (se96.0, spe73.7-68.4). Glucose and L/G predicted DCI 67 h before CT detection of a new infarct. The pathogenesis of DCI therefore induces early metabolic disturbances that can be detected by CMD as an advance warning. Glucose and L/G could provide a trigger for initiating further examination or therapy, earlier than when guided by other monitoring techniques.

Prediction of the mean transit time using machine learning models based on radiomics features from digital subtraction angiography in moyamoya disease or moyamoya syndrome-a development and validation model study

Background

Digital subtraction angiography (DSA) is an important technique for diagnosis of moyamoya disease (MMD) or moyamoya syndrome (MMS), and computed tomography perfusion (CTP) is essential for assessing intracranial blood supply. The aim of this study was to assess whether radiomics features based on images of DSA could predict the mean transit time (MTT; outcome of CTP) using machine learning models.

Methods

The DSA images and MTT values of adult patients with MMD or MMS, according to the diagnostic guidelines for MMD, as well as control cases, were retrospectively collected in the Guangdong Provincial People's Hospital between January 2018 and December 2020. A total of 93 features were extracted from the images of each case through 3-dimensional (3D) slicer. After features preprocessing and filtering, 3-4 features were selected by the least absolute shrinkage and selection operator (LASSO) regression algorithm. Prediction models were established using random forest (RF) and support vector machine (SVM) for MTT values. Single-factor receiver operating characteristic (ROC) curve analysis and partial-dependence (PD) profiles were conducted to investigate selected features and prediction models.

Results

Our results showed that prediction models based on RF models had the best performance in frontal lobe {area under the curve (AUC) [95% confidence interval (CI)] =1.000 (1.000-1.000)], parietal lobe [AUC (95% CI) =1.000 (1.000-1.000)], and basal ganglia/thalamus [AUC (95% CI) =0.922 (0.797-1.000)] in the test set, whereas the SVM model performed the best in the temporal lobe [AUC (95% CI) =0.962 (0.876-1.000)] in the test set. The AUC values in the test set were greater than 0.9. The PD profiles showed good robustness and consistency.

Conclusions

Prediction models based on radiomics features extracted from DSA images demonstrate excellent performance in predicting MTT in patients with MMD or MMS, which may provide guidance for future clinical practice.

Diagnosis of Delayed Cerebral Ischemia in Patients with Aneurysmal Subarachnoid Hemorrhage and Triggers for Intervention

INTRODUCTION

Delayed cerebral ischemia (DCI) is a major determinant for poor neurological outcome after aneurysmal subarachnoid hemorrhage (aSAH). Detection and treatment of DCI is a key component in the neurocritical care of patients with aSAH after initial aneurysm repair.

METHODS

Narrative review of the literature.

RESULTS

Over the past 2 decades, there has been a paradigm shift away from macrovascular (angiographic) vasospasm as a main diagnostic and therapeutic target. Instead, the pathophysiology of DCI is hypothesized to derive from several proischemic pathomechanisms. Clinical examination remains the most reliable means for monitoring and treatment of DCI, but its value is limited in comatose patients. In such patients, monitoring of DCI is usually based on numerous neurophysiological and/or radiological diagnostic modalities. Catheter angiography remains the gold standard for the detection of macrovascular spasm. Computed tomography (CT) angiography is increasingly used instead of catheter angiography because it is less invasive and may be combined with CT perfusion imaging. CT perfusion permits semiquantitative cerebral blood flow measurements, including the evaluation of the microcirculation. It may be used for prediction, early detection, and diagnosis of DCI, with yet-to-prove benefit on clinical outcome when used as a screening modality. Transcranial Doppler may be considered as an additional noninvasive screening tool for flow velocities in the middle cerebral artery, with limited accuracy in other cerebral arteries. Continuous electroencephalography enables detection of early signs of ischemia at a reversible stage prior to clinical manifestation. However, its widespread use is still limited because of the required infrastructure and expertise in data interpretation. Near-infrared spectroscopy, a noninvasive and continuous modality for evaluation of cerebral blood flow dynamics, has shown conflicting results and needs further validation. Monitoring techniques beyond neurological examinations may help in the detection of DCI, especially in comatose patients. However, these techniques are limited because of their invasive nature and/or restriction of measurements to focal brain areas.

CONCLUSION

The current literature review underscores the need for incorporating existing modalities and developing new methods to evaluate brain perfusion, brain metabolism, and overall brain function more accurately and more globally.

The oxygen reactivity index indicates disturbed local perfusion regulation after aneurysmal subarachnoid hemorrhage: an observational cohort study

BACKGROUND

Cerebral autoregulation (CA) can be impaired in patients with delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). The Pressure Reactivity Index (PRx, correlation of blood pressure and intracranial pressure) and Oxygen Reactivity Index (ORx, correlation of cerebral perfusion pressure and brain tissue oxygenation, PbtO2) are both believed to estimate CA. We hypothesized that CA could be poorer in hypoperfused territories during DCI and that ORx and PRx may not be equally effective in detecting such local variances.

METHODS

ORx and PRx were compared daily in 76 patients with aSAH with or without DCI until the time of DCI diagnosis. The ICP/PbtO2-probes of DCI patients were retrospectively stratified by being in or outside areas of hypoperfusion via CT perfusion image, resulting in three groups: DCI + /probe + (DCI patients, probe located inside the hypoperfused area), DCI + /probe-  (probe outside the hypoperfused area), DCI-  (no DCI).

RESULTS

PRx and ORx were not correlated (r = - 0.01, p = 0.56). Mean ORx but not PRx was highest when the probe was located in a hypoperfused area (ORx DCI + /probe + 0.28 ± 0.13 vs. DCI + /probe-  0.18 ± 0.15, p < 0.05; PRx DCI + /probe + 0.12 ± 0.17 vs. DCI + /probe-  0.06 ± 0.20, p = 0.35). PRx detected poorer autoregulation during the early phase with relatively higher ICP (days 1-3 after hemorrhage) but did not differentiate the three groups on the following days when ICP was lower on average. ORx was higher in the DCI + /probe + group than in the other two groups from day 3 onward. ORx and PRx did not differ between patients with DCI, whose probe was located elsewhere, and patients without DCI (ORx DCI + /probe-  0.18 ± 0.15 vs. DCI-  0.20 ± 0.14; p = 0.50; PRx DCI + /probe-  0.06 ± 0.20 vs. DCI-  0.08 ± 0.17, p = 0.35).

CONCLUSIONS

PRx and ORx are not interchangeable measures of autoregulation, as they likely measure different homeostatic mechanisms. PRx represents the classical cerebrovascular reactivity and might be better suited to detect disturbed autoregulation during phases with moderately elevated ICP. Autoregulation may be poorer in territories affected by DCI. These local perfusion disturbances leading up to DCI may be more readily detected by ORx than PRx. Further research should investigate their robustness to detect DCI and to serve as a basis for autoregulation-targeted treatment after aSAH.

Value of sildenafil treatment for the prevention of vasospasm‑related delayed ischemic neurological deficits and delayed brain infarction following aneurysmal subarachnoid hemorrhage

Cerebral vasospasm (CV) or delayed cerebral ischemia (DCI) constitutes the main reason for the unfavorable outcomes of patients with aneurysmal subarachnoid hemorrhage (aSAH). The present retrospective cohort study, through an evaluation with computed tomography (CT) perfusion (CTP), aimed to examine the utility of an intravenous or oral administration of sildenafil in preventing DCI that develops due to vasospasm in these patients. A retrospective cohort study was conducted, which included 34 patients in a tertiary care hospital. Of these patients, 18 were males (52.9%), and the median age was 54.4 years. Of these patients, 18 (52.9%) had undergone surgery, and 16 (47.1%) had an endovascular procedure. CTP was performed on the 3rd to the 6th day. The clinical outcome was documented at 30 days using a CT scan and a complete neurological evaluation, including the Glasgow Coma Scale assessment. There was a statistically significant difference in the number of patients who developed an ischemic event at 1 month between those who did not receive sildenafil compared to those who received sildenafil (P<0.05). In addition, the multivariate analysis revealed that cerebral blood flow was an independent factor for detecting an ischemic event in 1 month (P=0.001). On the whole, the findings of the present study indicate that the intravenous or oral administration of sildenafil may be beneficial for the prevention of DCI.

Pathophysiology of Early Brain Injury and Its Association with Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage: A Review of Current Literature

Background: Delayed cerebral ischemia (DCI) is a common and serious complication of aneurysmal subarachnoid hemorrhage (aSAH). Though many clinical trials have looked at therapies for DCI and vasospasm in aSAH, along with reducing rebleeding risks, none have led to improving outcomes in this patient population. We present an up-to-date review of the pathophysiology of DCI and its association with early brain injury (EBI). Recent Findings: Recent studies have demonstrated that EBI, as opposed to delayed brain injury, is the main contributor to downstream pathophysiological mechanisms that play a role in the development of DCI. New predictive models, including advanced monitoring and neuroimaging techniques, can help detect EBI and improve the clinical management of aSAH patients. Summary: EBI, the severity of subarachnoid hemorrhage, and physiological/imaging markers can serve as indicators for potential early therapeutics in aSAH. The microcellular milieu and hemodynamic pathomechanisms should remain a focus of researchers and clinicians. With the advancement in understanding the pathophysiology of DCI, we are hopeful that we will make strides toward better outcomes for this unique patient population.

Pictorial Review on Imaging Findings in Cerebral CTP in Patients with Acute Stroke and Its Mimics: A Primer for General Radiologists

The imaging evaluation of computed tomography (CT), CT angiography (CTA), and CT perfusion (CTP) is of crucial importance in the setting of each emergency department for suspected cerebrovascular impairment. A fast and clear assignment of characteristic imaging findings of acute stroke and its differential diagnoses is essential for every radiologist. Different entities can mimic clinical signs of an acute stroke, thus the knowledge and fast identification of stroke mimics is important. A fast and clear assignment is necessary for a correct diagnosis and a rapid initiation of appropriate therapy. This pictorial review describes the most common imaging findings in CTP with clinical signs for acute stroke or other acute neurological disorders. The knowledge of these pictograms is therefore essential and should also be addressed in training and further education of radiologists.

Optimal Cerebral Perfusion Pressure and Brain Tissue Oxygen in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Targeting a cerebral perfusion pressure optimal for cerebral autoregulation (CPPopt) has been gaining more attention to prevent secondary damage after acute neurological injury. Brain tissue oxygenation (PbtO2) can identify insufficient cerebral blood flow and secondary brain injury. Defining the relationship between CPPopt and PbtO2 after aneurysmal subarachnoid hemorrhage may result in (1) mechanistic insights into whether and how CPPopt-based strategies might be beneficial and (2) establishing support for the use of PbtO2 as an adjunctive monitor for adequate or optimal local perfusion.

METHODS

We performed a retrospective analysis of a prospectively collected 2-center dataset of patients with aneurysmal subarachnoid hemorrhage with or without later diagnosis of delayed cerebral ischemia (DCI). CPPopt was calculated as the cerebral perfusion pressure (CPP) value corresponding to the lowest pressure reactivity index (moving correlation coefficient of mean arterial and intracranial pressure). The relationship of (hourly) deltaCPP (CPP-CPPopt) and PbtO2 was investigated using natural spline regression analysis. Data after DCI diagnosis were excluded. Brain tissue hypoxia was defined as PbtO2 <20 mmHg.

RESULTS

One hundred thirty-one patients were included with a median of 44.0 (interquartile range, 20.8-78.3) hourly CPPopt/PbtO2 datapoints. The regression plot revealed a nonlinear relationship between PbtO2 and deltaCPP (P<0.001) with PbtO2 decrease with deltaCPP <0 mmHg and stable PbtO2 with deltaCPP ≥0mmHg, although there was substantial individual variation. Brain tissue hypoxia (34.6% of all measurements) was more frequent with deltaCPP <0 mmHg. These dynamics were similar in patients with or without DCI.

CONCLUSIONS

We found a nonlinear relationship between PbtO2 and deviation of patients' CPP from CPPopt in aneurysmal subarachnoid hemorrhage patients in the pre-DCI period. CPP values below calculated CPPopt were associated with lower PbtO2. Nevertheless, the nature of PbtO2 measurements is complex, and the variability is high. Combined multimodality monitoring with CPP/CPPopt and PbtO2 should be recommended to redefine individual pressure targets (CPP/CPPopt) and retain the option to detect local perfusion deficits during DCI (PbtO2), which cannot be fulfilled by both measurements interchangeably.

Efficacy of combined intravenous plus intrathecal nimodipine administration in patients with severe cerebral vasospasm post‑aneurysmal subarachnoid hemorrhage: A retrospective cohort study

Aneurysmal subarachnoid hemorrhage (aSAH) and the ensuing cerebral vasospasm (CV) and delayed cerebral ischemia (DCI) comprise the main reasons for morbidity and mortality in affected patients. The present study aimed to evaluate the efficacy of the use of combined intravenous (IV) and intrathecal (IT) nimodipine therapy for preventing permanent neurological deterioration and DCI in patients suffering from CV post-hemorrhage. The evaluation was performed using computed tomography perfusion and transcranial doppler ultrasound. The present retrospective cohort study analyzed 14 out of 146 patients diagnosed with vasospasm due to spontaneous or aSAH. These patients were divided into two groups as follows: i) The IV group, which included patients treated with only IV nimodipine; and ii) the IV + IT group, which included patients who received IV nimodipine in combination with IT nimodipine. Of the 14 patients, 7 patients were males (50%), and the mean age was 50.9 years (SD ±19 years). In total, 6 patients [42.8%; 5 (35.7%) from group A and 1 (7.1%) from group B], who experienced clinical symptoms with severe CV, were administered intra-arterial calcium channel therapy or/and IT nimodipine following the early identification of symptomatic vasospasm. The rate of adverse ischemic events was lower with IT nimodipine management during the 1 month of follow-up (6 vs. 2 events; odds ratio, 15.00; 95% confidence interval, 1.03-218.31; P=0.031). On the whole, the findings of the present study suggest that the combined use of IT nimodipine with IV admission for patients post-aSAH who developed severe CV is a safe procedure that may prevent permanent neurological deterioration and delay unfavorable ischemic incidents.

Early diagnosis of cerebral vasospasm associated with cerebral ischemia following subarachnoid hemorrhage: Evaluation of computed tomography perfusion and transcranial doppler as accurate methods

Cerebral vasospasm (CV) constitutes a major post-operative complication and source of morbidity in cases of subarachnoid hemorrhage (SAH). The early detection of CV in SAH may be difficult both clinically and radiographically. The present pilot study thus aimed to evaluate the practicability of the technique in a tertiary healthcare setting and to assess the diagnostic effectiveness of various diagnostic computed tomography (CT) perfusion (CTP) aspects in predicting the clinical outcome of patients with SAH (traumatic and aneurysmal). A retrospective study including 34 patients in a tertiary care hospital was thus conducted. The results revealed that of the 34 patients, 18 (52.9%) were males, and the mean age was 54.4±18.5 years (16-85 years old; range, 69 years). In total, 15 (44.1%) patients had traumatic SAH following traumatic brain injury (TBI), 11 (33.3%) had aneurysmal SAH, and 8 patients (23.6%) presented with TBI without SAH as controls. CTP was performed on the third to the sixth day, and 15-20 min prior to CPT, a transcranial Doppler ultrasound was performed. Clinical outcomes were documented at 30 days using a CT scan and a complete neurological evaluation, including Glasgow Coma Scale assessment. The results of a multivariate analysis revealed that cerebral blood flow (CBF) was an independent factor for detecting an ischemic event in 1 month (P=0.003). On the whole, the present study demonstrates that CTP, and consequently CBF, is a considerable index that may identify the onset of cerebral ischemia in patients with SAH.

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.

Cerebral Microdialysis-Based Interventions Targeting Delayed Cerebral Ischemia Following Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Delayed cerebral ischemia (DCI), a complication of subarachnoid hemorrhage (SAH), is linked to cerebral vasospasm and associated with poor long-term outcome. We implemented a structured cerebral microdialysis (CMD) based protocol using the lactate/pyruvate ratio (LPR) as an indicator of the cerebral energy metabolic status in the neurocritical care decision making, using an LPR ≥ 30 as a cutoff suggesting an energy metabolic disturbance. We hypothesized that CMD monitoring could contribute to active, protocol-driven therapeutic interventions that may lead to the improved management of patients with SAH.

METHODS

Between 2018 and 2020, 49 invasively monitored patients with SAH, median Glasgow Coma Scale 11 (range 3-15), and World Federation of Neurosurgical Societies scale 4 (range 1-5) on admission receiving CMD were included. We defined a major CMD event as an LPR ≥ 40 for ≥ 2 h and a minor CMD event as an LPR ≥ 30 for ≥ 2 h.

RESULTS

We analyzed 7,223 CMD samples over a median of 6 days (5-8). Eight patients had no CMD events. In 41 patients, 113 minor events were recorded, and in 23 patients 42 major events were recorded. Our local protocols were adhered to in 40 major (95%) and 98 minor events (87%), with an active intervention in 32 (76%) and 71 (63%), respectively. Normalization of energy metabolic status (defined as four consecutive samples with LPR < 30 for minor and LPR < 40 for major events) was seen after 69% of major and 59% of minor events. The incidence of DCI-related infarcts was 10% (five patients), with only two observed in a CMD-monitored brain region.

CONCLUSIONS

Active interventions were initiated in a majority of LPR events based on CMD monitoring. A low DCI incidence was observed, which may be associated with the active interventions. The potential aid of CMD in the clinical decision-making targeting DCI needs confirmation in additional SAH studies.

Large practice variations in diagnosis and treatment of delayed cerebral ischemia after subarachnoid hemorrhage

BACKGROUND

Delayed cerebral ischemia (DCI) contributes to poor outcomes after subarachnoid hemorrhage (SAH). The pathophysiology of DCI is not fully understood, which has hindered the adoption of a uniform definition. Furthermore, a reliable diagnostic test and an effective evidence-based treatment are lacking. This could lead to variations in care.

METHODS

A web-based survey on the variations in the definition, diagnosis, and treatment of DCI was designed and sent to 314 intensivists, neurologists, and neurosurgeons of all 9 hospitals in the Netherlands who care for patients with SAH. The responders were categorized into physicians responsible for the coordination of SAH care and those who were not. For questions on the definition and diagnosis, only the responses from the coordinating physicians were evaluated. For the treatment questions, all the responses were evaluated.

RESULTS

The response rate was 34% (106 of 314). All 9 hospitals were represented. Of the responses, 27 did not provide answers for the definition, diagnosis, or treatment questions; 79 responses were used for analysis. Signs of vasospasm were required by 21 of the 47 coordinating physicians (44%) when considering DCI. Of the 47 coordinating physicians, 24 (51%) did not use a diagnostic test results for a positive diagnosis of DCI. When patients were discharged within 21 days, 33 of the 73 responders (45%) did not provide a prescription for nimodipine continuation. Finally, all but one hospital had treated DCI with hypertension induction.

CONCLUSIONS

We found large variations in the definition, diagnosis, and treatment of DCI in the Netherlands. In the absence of evidence-based treatment, standardization of management seems warranted in an effort to optimize DCI care.

Optimal Cerebral Perfusion Pressure During Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

OBJECTIVES

The recommendation of induced hypertension for delayed cerebral ischemia treatment after aneurysmal subarachnoid hemorrhage has been challenged recently and ideal pressure targets are missing. A new concept advocates an individual cerebral perfusion pressure where cerebral autoregulation functions best to ensure optimal global perfusion. We characterized optimal cerebral perfusion pressure at time of delayed cerebral ischemia and tested the conformity of induced hypertension with this target value.

DESIGN

Retrospective analysis of prospectively collected data.

SETTING

University hospital neurocritical care unit.

PATIENTS

Thirty-nine aneurysmal subarachnoid hemorrhage patients with invasive neuromonitoring (20 with delayed cerebral ischemia, 19 without delayed cerebral ischemia).

INTERVENTIONS

Induced hypertension greater than 180 mm Hg systolic blood pressure.

MEASUREMENTS AND MAIN RESULTS

Changepoint analysis was used to calculate significant changes in cerebral perfusion pressure, optimal cerebral perfusion pressure, and the difference of cerebral perfusion pressure and optimal cerebral perfusion pressure 48 hours before delayed cerebral ischemia diagnosis. Optimal cerebral perfusion pressure increased 30 hours before the onset of delayed cerebral ischemia from 82.8 ± 12.5 to 86.3 ± 11.4 mm Hg (p < 0.05). Three hours before delayed cerebral ischemia, a changepoint was also found in the difference of cerebral perfusion pressure and optimal cerebral perfusion pressure (decrease from -0.2 ± 11.2 to -7.7 ± 7.6 mm Hg; p < 0.05) with a corresponding increase in pressure reactivity index (0.09 ± 0.33 to 0.19 ± 0.37; p < 0.05). Cerebral perfusion pressure at time of delayed cerebral ischemia was lower than in patients without delayed cerebral ischemia in a comparable time frame (cerebral perfusion pressure delayed cerebral ischemia 81.4 ± 8.3 mm Hg, no delayed cerebral ischemia 90.4 ± 10.5 mm Hg; p < 0.05). Inducing hypertension resulted in a cerebral perfusion pressure above optimal cerebral perfusion pressure (+12.4 ± 8.3 mm Hg; p < 0.0001). Treatment response (improvement of delayed cerebral ischemia: induced hypertension+ [n = 15] or progression of delayed cerebral ischemia: induced hypertension- [n = 5]) did not correlate to either absolute values of cerebral perfusion pressure or optimal cerebral perfusion pressure, nor the resulting difference (cerebral perfusion pressure [p = 0.69]; optimal cerebral perfusion pressure [p = 0.97]; and the difference of cerebral perfusion pressure and optimal cerebral perfusion pressure [p = 0.51]).

CONCLUSIONS

At the time of delayed cerebral ischemia occurrence, there is a significant discrepancy between cerebral perfusion pressure and optimal cerebral perfusion pressure with worsening of autoregulation, implying inadequate but identifiable individual perfusion. Standardized induction of hypertension resulted in cerebral perfusion pressures that exceeded individual optimal cerebral perfusion pressure in delayed cerebral ischemia patients. The potential benefit of individual blood pressure management guided by autoregulation-based optimal cerebral perfusion pressure should be explored in future intervention studies.

Multidisciplinary and standardized management of patients with delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

BACKGROUND

The appropriate management of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) remains uncertain. We aimed to evaluate the effect of implementing a standardized protocol for detection and management of DCI after aSAH on cerebral infarction and functional outcome.

METHODS

We studied two cohorts of aSAH patients, one before (pre-implementation cohort: January 2012 to August 2014) and one after (post-implementation cohort: January 2016 to July 2018) implementation of a multidisciplinary approach, with standardized neurological and radiological assessment and risk-based medical treatment of DCI. We assessed the presence of new hypodensities on CT within 6 weeks after aSAH and categorized cerebral infarction into overall and DCI-related infarctions (hypodensities not within 48 h after IA repair and not attributable to aneurysm occlusion or intraparenchymal hematoma). Functional outcome was assessed at 3 months using the extended Glasgow outcome scale (eGOS), dichotomized into unfavorable (eGOS: 1-5) and favorable (eGOS: 6-8). We calculated odds ratios (OR) with corresponding 95% confidence intervals (CI's), and adjusted for age, WFNS grade, Fisher score, and treatment modality (aOR).

RESULTS

In the post-implementation (n = 158) versus the pre-implementation (n = 143) cohort the rates for overall cerebral infarction were 29.1% vs 46.9% (aOR: 0.41 [0.24-0.69]), for DCI-related cerebral infarction 17.7% vs. 31.5% (aOR: 0.41 [0.23-0.76]), and for unfavorable functional outcome at 3 months 37.3% vs. 53.8% (aOR: 0.30 [0.17-0.54]). For patients with DCI, the rates for unfavorable functional outcomes at 3 months in the post-implementation versus the pre-implementation cohort were 42.3% vs. 77.8% (aOR: 0.1 [0.03-0.27]).

CONCLUSIONS

A multidisciplinary approach with more frequent and standardized neurological assessment, standardized CT and CT perfusion monitoring, as well as tailored application of induced hypertension and invasive rescue therapy strategies, is associated with a significant reduction of cerebral infarction and unfavorable functional outcome after aneurysmal aSAH.

Multimodality Monitoring for Delayed Cerebral Ischemia in Subarachnoid Hemorrhage: A Mini Review

Aneurysmal subarachnoid hemorrhage is a disease with high mortality and morbidity due in large part to delayed effects of the hemorrhage, including vasospasm, and delayed cerebral ischemia. These two are now recognized as overlapping yet distinct entities, and supportive therapies for delayed cerebral ischemia are predicated on identifying DCI as quickly as possible. The purpose of this overview is to highlight diagnostic tools that are being used in the identification of DCI in the neurocritical care settings.

Radiation Exposure in the Acute Phase after Aneurysmal Subarachnoid Hemorrhage in the Era of CT Perfusion

PURPOSE

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with a high risk of developing multiple complications requiring further diagnostics including imaging associated with radiation exposure (RE). Since aSAH often affects younger patients, the obtained cumulative RE may have serious long-term health consequences. The aim of this study was to calculate the cumulative RE in the acute phase after aSAH and to identify contributors to RE. Additionally, we investigated whether there is a correlation of RE with outcome.

METHODS

A retrospective analysis of patients with aSAH treated at our department from 2012 to 2018 was performed. The radiation dose of every single cranial radiological examination was calculated for every patient. The outcome was assessed according to the modified Rankin scale (mRS) 3 months after ictus. Factors associated with high RE were evaluated and the correlation of RE with outcome was assessed.

RESULTS

In 268 included consecutive patients, the mean cumulative RE per patient was 39.95 mSv, ranging from 2 to 265.5 mSv. A higher RE correlated with delayed cerebral ischemia (r = 0.52, p < 0.0001), delayed infarction (r = 0.25, p < 0.0001), delayed ischemic neurological deficits (r = 0.29, p < 0.0001) and transcranial Doppler (TCD)-vasospasm (r = 0.34, p < 0.0001). Independent predictors of outcome were age (p = 0.0001), World Federation of Neurosurgical Societies (WFNS) grade (p < 0.0001) and delayed infarction (p = 0.0004), while RE did not correlate with outcome.

CONCLUSION

There is a considerable imaging-related RE in aSAH patients. A meticulous decision-making process and imaging protocols with lower RE for the deployment of CT-based and fluoroscopy-based imaging is indicated in order to minimize the risk for radiation-mediated heath consequences in this patient population.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Delayed Cerebral Ischemia after Subarachnoid Hemorrhage

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

Aneurysmal Subarachnoid Hemorrhage: Review of the Pathophysiology and Management Strategies

PURPOSE OF REVIEW

Aneurysmal subarachnoid hemorrhage remains a devastating disease process despite medical advances made over the past 3 decades. Much of the focus was on prevention and treatment of vasospasm to reduce delayed cerebral ischemia and improve outcome. In recent years, there has been a shift of focus onto early brain injury as the precursor to delayed cerebral ischemia. This review will focus on the most recent data surrounding the pathophysiology of aneurysmal subarachnoid hemorrhage and current management strategies.

RECENT FINDINGS

There is a paucity of successful trials in the management of subarachnoid hemorrhage likely related to the targeting of vasospasm. Pathophysiological changes occurring at the time of aneurysmal rupture lead to early brain injury including cerebral edema, inflammation, and spreading depolarization. These events result in microvascular collapse, vasospasm, and ultimately delayed cerebral ischemia. Management of aneurysmal subarachnoid hemorrhage has remained the same over the past few decades. No recent trials have resulted in new treatments. However, our understanding of the pathophysiology is rapidly expanding and will advise future therapeutic targets.

Cerebral circulation time on DSA during endovascular treatment in WFNS grade I aneurysmal SAH patients-a predictor of DCI?

PURPOSE

Delayed cerebral ischemia (DCI) remains a contributor to poor outcome following aneurysmal subarachnoid hemorrhage (aSAH). We evaluated cerebral circulation time (CCT) on digital subtraction angiography (DSA) during endovascular treatment (EVT) in WFNS grade I aSAH patients as a predictor of DCI.

METHODS

Of 135 consecutive WNFS grade I aSAH patients, 90 were included. Age, gender, time of DSA from ictus (< 72 h or > 72 h), Fisher scale, severe vasospasm, development of DCI, EVD-dependent hydrocephalus, re-bleeding, and procedural complications were recorded. CCT was calculated retrospectively from multiphase DSA. Association with DCI was established through univariate and, subsequently, multivariable logistic regression. An optimal threshold value was identified using ROC curve analysis. Patient groups defined by threshold CCT value, DCI, and, subsequently, time of DSA from ictus were analyzed using χ² and Fisher's exact test.

RESULTS

CCT was the only significant factor in the multivariable logistic regression for the outcome development of DCI (OR/second increase in CCT = 1.46 [95% CI 1.14-1.86, p = .003]). When CCT was dichotomized at 8.5 s, the odds ratio for developing DCI was 7.12 (95% CI 1.93-26.34, p = .003) for CCT > 8.5 s compared with < 8.5 s. There was a significant difference for DCI in all patient groups dichotomized by CCT < 8.5 s and > 8.5 s (all patients, p = .001; patients imaged before and after 72 h of ictus, p = .024 and p = .034, respectively).

CONCLUSION

A CCT > 8.5 s on DSA during EVT in WFNS grade I aSAH patients is associated with an increased risk of developing DCI and may aid in the management of high-risk patients.

Intravenous milrinone for treatment of delayed cerebral ischaemia following subarachnoid haemorrhage: a pooled systematic review

Small trials have demonstrated promising results utilising intravenous milrinone for the treatment of delayed cerebral ischaemia (DCI) after subarachnoid haemorrhage (SAH). Here we summarise and contextualise the literature and discuss the future directions of intravenous milrinone for DCI. A systematic, pooled analysis of literature was performed in accordance with the PRISMA statement. Methodological rigour was analysed using the MINORS criteria. Extracted data included patient population; treatment protocol; and clinical, radiological, and functional outcome. The primary outcome was clinical resolution of DCI. Eight hundred eighteen patients from 10 single-centre, observational studies were identified. Half (n = 5) of the studies were prospective and all were at high risk of bias. Mean age was 52 years, and females (69%) outnumbered males. There was a similar proportion of low-grade (WFNS 1-2) (49.7%) and high-grade (WFNS 3-5) (50.3%) SAH. Intravenous milrinone was administered to 523/818 (63.9%) participants. Clinical resolution of DCI was achieved in 375/424 (88%), with similar rates demonstrated with intravenous (291/330, 88%) and combined intra-arterial-intravenous (84/94, 89%) therapy. Angiographic response was seen in 165/234 (71%) receiving intravenous milrinone. Hypotension (70/303, 23%) and hypokalaemia (31/287, 11%) were common drug effects. Four cases (0.5%) of drug intolerance occurred. Good functional outcome was achieved in 271/364 (74%) patients. Cerebral infarction attributable to DCI occurred in 47/250 (19%), with lower rates in asymptomatic spasm. Intravenous milrinone is a safe and feasible therapy for DCI. A signal for efficacy is demonstrated in small, low-quality trials. Future research should endeavour to establish the optimal protocol and dose, prior to a phase-3 study.

The role of imaging in the management of non-traumatic subarachnoid hemorrhage: a practical review

The purpose of this review is to understand the role of imaging in the diagnosis and management of non-traumatic subarachnoid hemorrhage (SAH). SAH is a life-threatening emergency and a relatively common entity, the most common etiology being ruptured aneurysms. Multiple conundrums exist in literature at various steps of its imaging workup: diagnosis, management, and follow-up. We target our review to highlight the most effective practice and suggest efficient workup plans based on literature search, and describe in detail the clinical diagnostic and prognostic scales, role of CT scan, lumbar puncture, and MR, including angiography in the diagnosis and workup of SAH and its complications, and try to simplify the conundrums. Practical knowledge of imaging workup of SAH can help guide correct management of these patients, so as to reduce morbidity and mortality without resource overutilization.

Machine Learning to Predict Delayed Cerebral Ischemia and Outcomes in Subarachnoid Hemorrhage

OBJECTIVE

To determine whether machine learning (ML) algorithms can improve the prediction of delayed cerebral ischemia (DCI) and functional outcomes after subarachnoid hemorrhage (SAH).

METHODS

ML models and standard models (SMs) were trained to predict DCI and functional outcomes with data collected within 3 days of admission. Functional outcomes at discharge and at 3 months were quantified using the modified Rankin Scale (mRS) for neurologic disability (dichotomized as good [mRS ≤ 3] vs poor [mRS ≥ 4] outcomes). Concurrently, clinicians prospectively prognosticated 3-month outcomes of patients. The performance of ML, SMs, and clinicians were retrospectively compared.

RESULTS

DCI status, discharge, and 3-month outcomes were available for 399, 393, and 240 participants, respectively. Prospective clinician (an attending, a fellow, and a nurse) prognostication of 3-month outcomes was available for 90 participants. ML models yielded predictions with the following area under the receiver operating characteristic curve (AUC) scores: 0.75 ± 0.07 (95% confidence interval [CI] 0.64-0.84) for DCI, 0.85 ± 0.05 (95% CI 0.75-0.92) for discharge outcome, and 0.89 ± 0.03 (95% CI 0.81-0.94) for 3-month outcome. ML outperformed SMs, improving AUC by 0.20 (95% CI -0.02 to 0.4) for DCI, by 0.07 ± 0.03 (95% CI -0.0018 to 0.14) for discharge outcomes, and by 0.14 (95% CI 0.03-0.24) for 3-month outcomes and matched physician's performance in predicting 3-month outcomes.

CONCLUSION

ML models significantly outperform SMs in predicting DCI and functional outcomes and has the potential to improve SAH management.

Neurovascular disease, diagnosis, and therapy: Subarachnoid hemorrhage and cerebral vasospasm

The worldwide incidence of spontaneous subarachnoid hemorrhage is about 6.1 per 100,000 cases per year (Etminan et al., 2019). Eighty-five percent of cases are due to intracranial aneurysms. The mean age of those affected is 55 years, and two-thirds of the patients are female. The prognosis is related mainly to the neurologic condition after the subarachnoid hemorrhage and the age of the patient. Overall, 15% of patients die before reaching the hospital, another 20% die within 30 days, and overall 75% are dead or remain disabled. Case fatality has declined by 17% over the last 3 decades. Despite the improvement in outcome probably due to improved diagnosis, early aneurysm repair, administration of nimodipine, and advanced intensive care support, the outcome is not very good. Even among survivors, 75% have permanent cognitive deficits, mood disorders, fatigue, inability to return to work, and executive dysfunction and are often unable to return to their premorbid level of functioning. The key diagnostic test is computed tomography, and the treatments that are most strongly supported by scientific evidence are to undertake aneurysm repair in a timely fashion by endovascular coiling rather than neurosurgical clipping when feasible and to administer enteral nimodipine. The most common complications are aneurysm rebleeding, hydrocephalus, delayed cerebral ischemia, and medical complications (fever, anemia, and hyperglycemia). Management also probably is optimized by neurologic intensive care units and multidisciplinary teams.

Update: Microdialysis for Monitoring Cerebral Metabolic Dysfunction after Subarachnoid Hemorrhage

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

Current and novel non-invasive imaging modalities in vascular neurosurgical practice

Radiological investigations are a powerful tool in the assessment of patients with intracranial vascular anomalies. 'Visual' assessment of neurovascular lesions is central to their diagnosis, monitoring, prognostication and management. Computed tomography and magnetic resonance imaging are the two principal non-invasive imaging modalities used in clinical practice for the assessment of the cerebral vasculature, but these techniques continue to evolve, enabling clinicians to gain greater insights into neurovascular pathology and pathophysiology. This review outlines both established and novel imaging modalities used in modern neurovascular practice and their clinical applications.

Computed tomography perfusion imaging after aneurysmal subarachnoid hemorrhage can detect cerebral vasospasm and predict delayed cerebral ischemia after endovascular treatment

Background

Endovascular treatment (ET) can improve angiographic cerebral vasospasm (CV) after aneurysmal subarachnoid hemorrhage, but was unrelated to clinical outcomes in previous analyses. Appropriate detection of CV and precise indications for ET are required. This study investigated whether changes in computed tomography perfusion (CTP) parameter can determine indications for ET in CV and predict its effectiveness.

Methods

Participants comprised 140 patients who underwent neck clipping or coil embolization. CTP was performed a week after aneurysmal treatment or when clinical deterioration had occurred. Patients were divided into ET and non-ET groups by propensity score matching. In addition, the ET group was divided into subgroups with and without new cerebral infarction (CI). All CTP images in the three groups were retrospectively investigated qualitatively and quantitatively. CI was diagnosed from CT at 3 months postoperatively.

Results

Of the 121 patients examined, 15 patients (11%) needed ET. In qualitative analysis, all ET group patients displayed extension of time-to-peak (TTP) at the region of vasospastic change, regardless of the presence of CI. Quantitative analysis showed significant decreases in cerebral blood volume (P < 0.01), cerebral blood flow (CBF) (P < 0.001), and extension in TTP (P < 0.01) in the ET group compared with the non-ET group. A significant decrease in CBF (P < 0.001) and extension in mean transit time (P < 0.001) was seen in the ET with CI subgroup compared with the ET without CI subgroup.

Conclusion

CTP in the vasospastic period may be an indication for ET and predict the effectiveness of ET for CV to improve clinical outcomes.

TNF-R1 Correlates with Cerebral Perfusion and Acute Ischemia Following Subarachnoid Hemorrhage

BACKGROUND

Early cerebral hypoperfusion and ischemia occur after subarachnoid hemorrhage (SAH) and influence clinical prognosis. Pathophysiological mechanisms possibly involve inflammatory mediators. TNF-α has been associated with complications and prognosis after SAH. We investigated the relation of perfusion parameters and ischemic lesions, with levels of TNF-α main receptor, TNF-R1, after SAH, and their association with prognosis.

METHODS

We included consecutive SAH patients admitted within the first 72 h of SAH onset. Blood samples were simultaneously collected from a peripheral vein and from the parent artery of the aneurysm. Levels of TNF-R1 were measured using ELISA (R&D Systems Inc., USA). CT perfusion and MRI studies were performed in the first 72 h. Correlation and logistic regression analysis were used to identify outcome predictors.

RESULTS

We analyzed 41 patients. Increased levels of TNF-R1 correlated with increased T_max (arterial: r = -0.37, p = 0.01) and prolonged MTT (arterial: r = 0.355, p = 0.012; venous: r = 0.306, p = 0.026). Increased levels of both arterial and venous TNF-R1 were associated with increased number of lesions on DWI (p = 0.006). In multivariate analysis, venous TNFR1 levels > 1742.2 pg/mL (OR 1.78; 95%CI 1.18-2.67; p = 0.006) and DWI lesions (OR 14.01; 95%CI 1.19-165.3; p = 0.036) were both independent predictors of poor outcome (mRS ≥ 3) at 6 months.

CONCLUSION

Increased levels of TNF-R1 in arterial and venous blood correlate with worse cerebral perfusion and with increased burden of acute ischemic lesions in the first 72 h after SAH. Venous levels of TNF-R1 and DWI lesions were associated with poor outcome at 6 months. These results highlight the pathophysiological role of TNF-α pathways in SAH and suggest a possible role of combined imaging and laboratorial markers in determining prognosis in acute SAH.

Heart rate variability monitoring for the detection of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

BACKGROUND

Delayed cerebral ischemia (DCI) is a major cause of impaired outcome after aneurysmal subarachnoidal hemorrhage (aSAH). In this observational cohort study we investigated whether changes in heart rate variability (HRV) that precede DCI could be detected.

METHODS

Sixty-four patients with aSAH were included. HRV data were collected for up to 10 days and analyzed offline. Correlation with clinical status and/or radiologic findings was investigated. A linear mixed model was used for the evaluation of HRV parameters over time in patients with and without DCI. Extended Glasgow outcome scale score was assessed after 1 year.

RESULTS

In 55 patients HRV data could be analyzed. Fifteen patients developed DCI. No changes in HRV parameters were observed 24 hours before onset of DCI. Mean of the HRV parameters in the first 48 hours did not correlate with the development of DCI. Low/high frequency (LF/HF) ratio increased more in patients developing DCI (β -0.07 (95% confidence interval, 0.12-0.01); P = .012). Lower STDRR (standard deviation of RR intervals), RMSSD (root mean square of the successive differences between adjacent RR intervals), and total power (P = .003, P = .007 and P = .004 respectively) in the first 48 hours were seen in patients who died within 1 year.

CONCLUSION

Impaired HRV correlated with 1-year mortality and LF/HF ratio increased more in patients developing DCI. Even though DCI could not be detected by the intermittent analysis of HRV used in this study, continuous HRV monitoring may have potential in the detection of DCI after aSAH using different methods of analysis.

Efficacy of exercise rehabilitation program accompanied by experiential music for recovery of aphasia in single cerebrovascular accidents: a randomized controlled trial

BACKGROUND

The current study aims to evaluate the effects of daily traditional experiential music listening for clinical recovery of post-stroke aphasia.

METHODS

This was a prospective randomized trial with seventy-nine stroke survivors who suffered from post-stroke aphasia. All patients underwent a neuropsychological evaluation, at time = 0 during the admission at the rehabilitation structure (baseline), and 6 months post-stroke. All cases received standard treatment for stroke and post-stroke aphasia in terms of medical care and rehabilitation. Furthermore, patients were randomized to receive either standard care only or standard care with daily traditional experiential music listening. Computer tomography perfusion and neurological examination were assessed to all patients. Recovery was measured by the score at Aachener Aphasie Test.

RESULTS

The statistically significant differences between the control group (CG) and the rest of the patients were the clinical characteristics (hemiparesis) (p = 0.002), the cerebral blood flow in affected areas (p = 0.000), and the Mini-Mental Test (mMT) (p = 0.000). Only group and mMT were independent predictor factors for recovery, according to multivariate analysis odd ratio (ΟR) (95% confidence interval) 0.022 (0.009-0.435) and 0.658 (0.142-0.224) respectively.

CONCLUSIONS

The results of this study are promising and suggest that an enriched sound environment is beneficial for patients with post-stroke aphasia since the recovery rate is higher when standard care was combined with daily music listening.

Optimal intracranial pressure in patients with aneurysmal subarachnoid hemorrhage treated with coiling and requiring external ventricular drainage

Optimal management of intracranial pressure (ICP) among aneurysmal subarachnoid hemorrhage (aSAH) patients requiring external ventricular drainage (EVD) is controversial. To analyze predictors of delayed cerebral ischemia (DCI)-related cerebral infarction after aSAH and the influence of ICP values on DCI, we prospectively collected consecutive patients with aSAH receiving coiling and requiring EVD. Predictors of DCI-related cerebral infarction (new CT hypodensities developed within the first 3 weeks not related to other causes) were studied. Vasospasm and brain hypoperfusion were studied with CT angiography and CT perfusion (RAPID-software). Among 50 aSAH patients requiring EVD, 21 (42%) developed DCI-related cerebral infarction, while 27 (54%) presented vasospasm. Mean ICP ranged between 2 and 19 mmHg. On the multivariate analysis, the mean ICP (OR = 2, 95%CI = 1.01-3.9, p = 0.042) and the mean hypoperfusion volume on Tmax delay > 6 (OR = 1.2, 95%CI = 1.01-1.3, p = 0.025) were independent predictors of DCI. To predict DCI-related cerebral infarction, Tmax delay > 6 s presented the highest AUC (0.956, SE = 0.025), with a cutoff value of 18 ml showing sensitivity, specificity, PPV, NPV, and accuracy of 90.5% (95%CI = 69-98.8%), 86.2% (95%CI = 68.4-96%), 82.6% (95%CI = 65.4-92%), 92.5% (95%CI = 77-98%), and 88% (95%CI = 75-95%), respectively. The AUC of the mean ICP was 0.825 (SE = 0.057), and the best cutoff value was 6.7 mmHg providing sensitivity, specificity, PPV, NPV, and accuracy of 71.4% (95%CI = 48-89%), 62% (95%CI = 42-79%), 58% (95%CI = 44-70%), 75% (95%CI = 59-86%), and 66% (95%CI = 51-79%) for the prediction of DCI-related cerebral infarction, respectively. Among aSAH patients receiving coiling and EVD, lower ICP (< 6.7 mmHg in our study) could potentially be beneficial in decreasing DCI-related cerebral infarction. Brain hypoperfusion with a volume > 18 ml at Tmax delay > 6 s presents a high sensibility and specificity in prediction of DCI-related cerebral infarction.

Assessing Contribution of Higher Order Clinical Risk Factors to Prediction of Outcome in Aneurysmal Subarachnoid Hemorrhage Patients

The goal of this study was to investigate the application of machine learning models capable of capturing multiplica tive and temporal clinical risk factors for outcome prediction inpatients with aneurysmal subarachnoid hemorrhage (aSAH). We examined a cohort of 575 aSAH patients from Emory Healthcare, identified via digital subtraction angiog- raphy. The outcome measure was the modified Ranking Scale (mRS) after 90 days. Predictions were performed with longitudinal clinical and imaging risk factors as inputs into a regularized Logistic Regression, a feedforward Neural Network and a multivariate time-series prediction model known as the long short-term memory (LSTM) architecture. Through extraction of higher-order risk factors, the LSTM model achieved an AUC of 0.89 eight days into hospitaliza tion, outperforming other techniques. Our preliminary findings indicate the proposed model has the potential to aid treatment decisions and effective imaging resource utilization in high-risk patients by providing actionable predictions prior to the development of neurological deterioration.

Temporal evolution of cerebral computed tomography perfusion after acute subarachnoid hemorrhage: a prospective cohort study

Background

Changes in cerebral perfusion occur in subarachnoid hemorrhage that possibly relate to clinical presentation and complications.

Purpose

To evaluate changes in computed tomography perfusion (CTP) parameters between the acute and subacute stage of subarachnoid hemorrhage. To analyze correlation of these parameters to SAH severity and delayed cerebral ischemia.

Material and Methods

Cerebral CT perfusion was assessed in a prospective cohort of 44 patients with acute subarachnoid hemorrhage at < 72 h (CTP1) and 8–10 days (CTP2), using the mean of all regions of interest. Regions of interest were located at arterial territories of the anterior, middle, and posterior cerebral artery and basal ganglia and midpons cerebellar hemispheres. Linear regression models (univariable and multivariable) were used to explore the association between changes in perfusion parameters (absolute and relative differences) and relevant clinical data.

Results

Worse perfusion parameters on the first 72 h were correlated with poor admission clinical scores: cerebral blood flow positively correlated with Glasgow Coma Scale (rS = 0.398, P = 0.008), and negatively correlated with Hunt & Hess scale (rS = −0.348, P = 0.020) and World Federation of Neurosurgeons scale (rS = −0.384, P = 0.010). Cerebral blood volume positively correlated with Glasgow Coma Scale (rS = 0.332, P = 0.028) and negatively correlated with World Federation of Neurosurgeons scale (rS = −0.353, P = 0.019). Mean transit time negatively correlated with Glasgow Coma Scale (rS = −0.415, P = 0.005) and positively correlated with Hunt & Hess scale (rS = 0.471, P = 0.001) and World Federation of Neurosurgeons scale (rS = 0.386, P = 0.010) scores. There were no differences between absolute CTP1/CTP2 parameters. Patients with delayed cerebral ischemia had ΔTmax mean decrease of 2.08 s (95% CI = −4.04–−0.12; P = 0.038).

Conclusion

Early cerebral hypoperfusion correlates with poor clinical grade at admission in subarachnoid hemorrhage and with higher amounts of blood. Tmax was decreased at 8–10 days, in patients with delayed cerebral ischemia, which may favor the application value of Tmax in signaling delayed cerebral ischemia.

Common Data Elements for Radiological Imaging of Patients with Subarachnoid Hemorrhage: Proposal of a Multidisciplinary Research Group

INTRODUCTION

Lack of homogeneous definitions for imaging data and consensus on their relevance in the setting of subarachnoid hemorrhage and unruptured intracranial aneurysms lead to a difficulty of data pooling and lack of robust data. The aim of the National Institute of Health/National Institute of Neurological Disorders and Stroke, Unruptured Intracranial Aneurysm (UIA) and Subarachnoid Hemorrhage (SAH) Common Data Elements (CDE) Project was to standardize data elements to ultimately facilitate data pooling and establish a more robust data quality in future neurovascular research on UIA and SAH.

METHODS

For the subcommittee 'Radiological imaging of SAH,' international cerebrovascular specialists with imaging expertise in the setting of SAH were selected by the steering committee. CDEs were developed after reviewing the literature on neuroradiology and already existing CDEs for other neurological diseases. For prioritization, the CDEs were classified into 'Core,' 'Supplemental-Highly Recommended,' 'Supplemental' and 'Exploratory.'

RESULTS

The subcommittee compiled 136 CDEs, 100 out of which were derived from previously established CDEs on ischemic stroke and 36 were newly created. The CDEs were assigned to four main categories (several CDEs were assigned to more than one category): 'Parenchymal imaging' with 42 CDEs, 'Angiography' with 49 CDEs, 'Perfusion imaging' with 20 CDEs, and 'Transcranial doppler' with 55 CDEs. The CDEs were classified into core, supplemental highly recommended, supplemental and exploratory elements. The core CDEs were imaging modality, imaging modality type, imaging modality vessel, angiography type, vessel angiography arterial anatomic site and imaging vessel angiography arterial result.

CONCLUSIONS

The CDEs were established based on the current literature and consensus across cerebrovascular specialists. The use of these CDEs will facilitate standardization and aggregation of imaging data in the setting of SAH. However, the CDEs may require reevaluation and periodic adjustment based on current research and improved imaging quality and novel modalities.

[Significance of CT perfusion examination of cerebral blood flow for assessing the risk of brain ischemia in patients with intracranial arterial aneurysm ruptures]

Prognosing the outcome of cerebral ischemia in the acute SAH phase still remains the topical issue for clinical practice because this largely affects the choice of an optimal timing of aneurysm clipping. The traditional criteria are often not effective enough to predict changes in cerebral ischemia, especially in patients in a compensated or subcompensated state who often develop delayed ischemia, which may lead to serious complications. The introduction of a CT perfusion technique for evaluating the volumetric cerebral blood flow stimulated the development of a new stage in investigation of cerebral ischemia in non-traumatic SAH.

PURPOSE

The study purpose was to evaluate the significance of cerebral blood flow indicators obtained by CT perfusion for prediction of delayed cerebral ischemia and postoperative ischemic complications to optimize treatment of patients with ruptures of intracranial arterial aneurysms.

MATERIAL AND METHODS

The study included 70 patients who underwent aneurysm clipping and 42 non-operated patients. The inclusion criteria were as follows: WFNS grade I-III condition, vasospasm according to transcranial Doppler sonography, and availability of CT scans, including CT perfusion data. The vasospasm severity and perfusion indicators _(rCBV and MTT) were evaluated. The severity of subarachnoid and ventricular hemorrhage was evaluated according to the A. Hijdra method. The final results were evaluated using a clinical-statistical method, including ROC analysis.

RESULTS

An analysis of the obtained data revealed that the risk of delayed cerebral ischemia and postoperative ischemia increases significantly if the baseline hemispheric CBF value is below a threshold of 40 ml/100 g/min, and the baseline MMT indicator is above a threshold of 5 s. There was asymmetry of these CT perfusion indicators due to a larger deviation from the threshold values in the homolateral hemisphere compared to the opposite side. The ROC analysis results demonstrated diagnostic sensitivity and diagnostic specificity of the CT perfusion technique.

CONCLUSION

The CT perfusion data together with the SAH severity and localization indicators may be used as predictors for the cerebral ischemia outcome in choosing the optimal timing of aneurysm clipping during the acute SAH period in patients in a WFNS grade I-III condition and with signs of mild or moderate vasospasm.

Mass spectrometry-based method for quantification of nimodipine and glutamate in cerebrospinal fluid. Pilot study with patients after aneurysmal subarachnoid haemorrhage

WHAT IS KNOWN AND OBJECTIVE

Delayed cerebral ischaemia is an important cause of morbidity and mortality after aneurysmal subarachnoid haemorrhage (aSAH). Nimodipine is the only drug approved by the FDA for improving outcome after aSAH. Clinically, however, there are no specific values of this drug in cerebrospinal fluid (CSF) during aSAH treatment that could be associated to outcome improvement. Furthermore, the neurotransmitter glutamate acts as a secondary marker for brain injury. The aim was to establish a method to measure nimodipine and glutamate concentrations simultaneously in CSF of patients after aSAH.

METHODS

From June 2017 to June 2018, we prospectively collected clinical data of patients with aSAH admitted to our neurointensive care unit. All included patients received nimodipine orally (60 mg every 4 hours). Patients, who developed clinical vasospasm during their in-hospital stay, underwent intra-arterial application of nimodipine (IAN), followed by angiographic control. A method using high-performance liquid chromatography coupled with mass spectrometric analysis (LC-MS/MS) was established for quantification of both analytes in CSF.

RESULTS AND DISCUSSION

In 15 (60%) of 25 patients, nimodipine and glutamate concentrations were measured. After IAN for treatment of vasospasms, CSF nimodipine concentrations were slightly higher than in patients who received nimodipine only orally (0.60 ± 0.27 ng/mL vs 0.48 ± 0.18 ng/mL). Patients developing vasospasm exhibited higher glutamate concentrations than patients without vasospasm (188.84 ng/mL vs136.07 ng/mL).

WHAT IS NEW AND CONCLUSION

The developed method allowed the simultaneous quantification of nimodipine and glutamate in CSF. Furthermore, we demonstrated that IAN resulted in higher concentrations in CSF, when compared to oral application only.

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.