Vasospasm probability index: a combination of transcranial doppler velocities, cerebral blood flow, and clinical risk factors to predict cerebral vasospasm after aneurysmal subarachnoid hemorrhage

Establishing normal Lindegaard Ratio in healthy children 10-16 years of age

PURPOSE

Transcranial doppler based diagnostic criteria for cerebral vasospasm are not well established in the pediatric population because there is no published normative data to support the diagnosis. Studies have relied on expert consensus, but the definitions have not been validated in children diagnosed with angiographic evidence of vasospasm. Obtaining normative data is a prerequisite to defining pediatric cerebral vasospasm and the Lindegaard Ratio (LR). In this study, we obtained normative data and calculation of the normal LR from healthy children aged 10-16 years.

METHODS

TCD and carotid ultrasonography was used to measure steady state velocities of both the middle cerebral artery (VMCA) and the extracranial internal cerebral artery (VEICA) in healthy children aged 10-16 years. Demographic information, hemodynamic characteristics and the calculated LR (VMCA/VEICA) was determined for each subject using descriptive statistics.

RESULTS

Of the 26 healthy children, 13 were male and 13 were female. VMCA ranged between 53 and 93 cm/sec. LR ranged between 1 and 2.2 for the cohort. VMCA for both males and females were within 2 standard deviations (SD) of the normal mean flow velocity. As the VMCA velocities approached 2 SD above the mean, LR did not exceed 2.2.

CONCLUSION

Our results help define a threshold for LR which can be used to establish radiographic criteria for cerebral vasospasm in children. Our data suggests that using VMCA criteria alone would overestimate cerebral vasospasm and raises question of whether an LR threshold other than 3 is more appropriate for the cut off between hyperemia versus vasospasm in children.

Troponin I as a Predictor of Transcranial Doppler Sonography Defined Vasospasm in Intensive Care Unit Patients After Spontaneous Subarachnoid Hemorrhage

OBJECTIVE

Elevation of Troponin I (TnI) in spontaneous subarachnoid hemorrhage (SAH) patients is a well-known phenomenon and associated with cardiopulmonary complications and poor outcome. The present study was conducted to investigate the association of the TnI value on admission, and the occurrence of cerebral vasospam in SAH patients.

PATIENTS AND METHODS

A total of 142 patients with SAH, who were admitted to the neurosurgical intensive care unit (ICU) between December 2014 and January 2021 were evaluated. Blood samples were drawn on admission to determine TnI value. Each patient's demographic, radiological and medical data on admission, the modified Ranking Scale score at discharge as well as continuous measurements of transcranial Doppler sonography were analyzed. A maximum mean flow velocity (MMFV) > 120 cm/sec was defined as any vasospasm. These were stratified into severe vasospasms, which were defined as at least two measurements of MMFVs > 200 cm/sec or an increase of MMFV > 50 cm/sec/24 h over two consecutive days or a new neurological deterioration and mild vasospasm defined as MMFVs > 120 cm/sec in absence of severe vasospasm criteria. The total study population was dichotomized into patients with an initially elevated TnI (>0.05 µg/L) and without elevated TnI (≤0.05 μg/L).

RESULTS

A total of 52 patients (36.6%) had an elevated TnI level upon admission, which was significantly associated with lower GCS score (p < 0.001), higher WFNS score (p < 0.001) and higher Fisher grade (p = 0.01) on admission. In this context a higher rate of ischemic brain lesions (p = 0.02), a higher modified Rankin Scale score (p > 0.001) and increased mortality (p = 0.02) at discharge were observed in this group. In addition, TnI was identified as an independent predictor for the occurrence of any vasospasm and severe vasospasm.

CONCLUSION

An initially elevated TnI level is an independent predictor for the occurrence of any and severe vasospasm in patients with SAH.

Ultrasonographic Vasospasm and Outcome of Posterior Reversible Encephalopathy and Cerebral Vasoconstriction Syndromes

PURPOSE

Posterior reversible encephalopathy syndrome (PRES) and reversible cerebral vasoconstriction syndrome (RCVS) are often complicated by vasospasm and ischemia. Monitoring with transcranial color-coded Doppler (TCCD) could be useful, but its role is not established. We studied the incidence of ultrasonographic vasospasm (uVSP) in PRES/RCVS and its relationship with ischemic lesions and clinical outcome.

MATERIALS AND METHODS

We conducted a multicenter retrospective study of all patients with PRES/RCVS from 2008 to 2020 who underwent TCCD and magnetic resonance imaging (MRI). TCCD exams were analyzed for uVSP. Diffusion-weighted MRI was analyzed for positive lesions (DWI-positive). Functional outcome was assessed by modified Rankin scale (mRS) at 90 days. The associations with outcomes were determined by logistic regression.

RESULTS

We included 80 patients (mean age of 46 (standard deviation, 17) years; 66% females; 41 with PRES, 28 with RCVS and 11 with overlap phenotype). uVSP was detected in 25 (31%) patients. DWI-positive lesions were more often detected in uVSP-positive than uVSP-negative patients (36% vs. 15%; adjusted odds ratio [aOR] 4.05 [95% CI 1.06 - 15.5], P=0.04). DWI-positive lesions were independently associated with worse functional prognosis (mRS 2-6, 43% vs. 10%; aOR, 10 [95% CI 2.6 - 43], P<0.01). Having additional uVSP further increased the odds of a worse outcome (P interaction=0.03).

CONCLUSION

Ultrasonographic vasospasm was detected in a third of patients with PRES/RCVS and was associated with brain ischemic lesions. TCCD bedside monitoring can help to stratify patients at risk for cerebral ischemia, a strong predictor of functional outcome.

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 TCD hyperemia index to detect vasospasm and delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Elevated mean flow velocity (MFV) on transcranial Doppler (TCD) is used to predict vasospasm after aneurysmal subarachnoid hemorrhage (SAH). Hyperemia should be considered when observing elevated MFV. Lindegaard ratio (LR) is commonly used but does not enhance predictive values. We introduce a new marker, the hyperemia index (HI), calculated as bilateral extracranial internal carotid artery MFV divided by initial flow velocity.

METHODS

We evaluated SAH patients hospitalized ≥7 days between December 1, 2016 and June 30, 2022. We excluded patients with nonaneurysmal SAH, inadequate TCD windows, and baseline TCD obtained after 96 hours from onset. Logistic regression was conducted to assess the significant associations of HI, LR, and maximal MFV with vasospasm and delayed cerebral ischemia (DCI). Receiver operating characteristic analyses were employed to find the optimal cutoff value for HI.

RESULTS

Lower HI (odds ratio [OR] 0.10, 95% confidence interval [CI] 0.01-0.68), higher MFV (OR 1.03, 95% CI 1.01-1.05), and LR (OR 2.02, 95% CI 1.44-2.85) were associated with vasospasm and DCI. Area under the curve (AUC) for predicting vasospasm was 0.70 (95% CI 0.58-0.82) for HI, 0.87 (95% CI 0.81-0.94) for maximal MFV, and 0.87 (95% CI 0.79-0.94) for LR. The optimal cutoff value for HI was 1.2. Combining HI <1.2 with MFV improved positive predictive value without altering the AUC value.

CONCLUSIONS

Lower HI was associated with a higher likelihood of vasospasm and DCI. HI <1.2 may serve as a useful TCD parameter to indicate vasospasm and DCI when elevated MFV is observed, or when transtemporal windows are inadequate.

Neurobehavioral Impairments Predict Specific Cerebral Damage in Rat Model of Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a severe form of stroke that can cause unpredictable and diffuse cerebral damage, which is difficult to detect until it becomes irreversible. Therefore, there is a need for a reliable method to identify dysfunctional regions and initiate treatment before permanent damage occurs. Neurobehavioral assessments have been suggested as a possible tool to detect and approximately localize dysfunctional cerebral regions. In this study, we hypothesized that a neurobehavioral assessment battery could be a sensitive and specific method for detecting damage in discrete cerebral regions following SAH. To test this hypothesis, a behavioral battery was employed at multiple time points after SAH induced via an endovascular perforation, and brain damage was confirmed via postmortem histopathological analysis. Our results demonstrate that impairment of sensorimotor function accurately predict damage in the cerebral cortex (AUC 0.905; sensitivity 81.8%; specificity 90.9%) and striatum (AUC 0.913; sensitivity 90.1%; specificity 100%), while impaired novel object recognition is a more accurate indicator of damage to the hippocampus (AUC 0.902; sensitivity 74.1%; specificity 83.3%) than impaired reference memory (AUC 0.746; sensitivity 72.2%; specificity 58.0%). Tests for anxiety-like and depression-like behaviors predict damage to the amygdala (AUC 0.900; sensitivity 77.0%; specificity 81.7%) and thalamus (AUC 0.963; sensitivity 86.3%; specificity 87.8%), respectively. This study suggests that recurring behavioral testing can accurately predict damage in specific brain regions, which could be developed into a clinical battery for early detection of SAH damage in humans, potentially improving early treatment and outcomes.

Neurobehavioral impairments predict specific cerebral damage in rat model of subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a severe form of stroke that can cause unpredictable and diffuse cerebral damage, which is difficult to detect until it becomes irreversible. Therefore, there is a need for a reliable method to identify dysfunctional regions and initiate treatment before permanent damage occurs. Neurobehavioral assessments have been suggested as a possible tool to detect and approximately localize dysfunctional cerebral regions. In this study, we hypothesized that a neurobehavioral assessment battery could be a sensitive and specific early warning for damage in discrete cerebral regions following SAH. To test this hypothesis, a behavioral battery was employed at multiple time points after SAH induced via an endovascular perforation, and brain damage was confirmed via postmortem histopathological analysis. Our results demonstrate that impairment of sensorimotor function accurately predict damage in the cerebral cortex (AUC: 0.905; sensitivity: 81.8%; specificity: 90.9%) and striatum (AUC: 0.913; sensitivity: 90.1%; specificity: 100%), while impaired novel object recognition is a more accurate indicator of damage to the hippocampus (AUC: 0.902; sensitivity: 74.1%; specificity: 83.3%) than impaired reference memory (AUC: 0.746; sensitivity: 72.2%; specificity: 58.0%). Tests for anxiety-like and depression-like behaviors predict damage to the amygdala (AUC: 0.900; sensitivity: 77.0%; specificity: 81.7%) and thalamus (AUC: 0.963; sensitivity: 86.3%; specificity: 87.8%), respectively. This study suggests that recurring behavioral testing can accurately predict damage in specific brain regions, which could be developed into a clinical battery for early detection of SAH damage in humans, potentially improving early treatment and outcomes.

The Role of VASOGRADE as a Simple Grading Scale to Predict Delayed Cerebral Ischemia and Functional Outcome After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

The VASOGRADE is a simple aneurysmal subarachnoid hemorrhage (aSAH) grading scale that combines the modified Fisher scale (mFisher) and the World Federation of Neurological Societies (WFNS) grading system, allowing the stratification of delayed cerebral ischemia (DCI) risk. However, the VASOGRADE accuracy in predicting functional outcomes is still to be determined.

METHODS

We retrospectively evaluated a multiethnic cohort of consecutive patients with aSAH admitted to a high-volume center in Brazil from January 2016 to January 2019. Patients were classified according to the severity of the clinical presentation (WFNS), the amount of blood in the initial head computerized tomography (mFisher) scan, and the VASOGRADE (green, yellow, red). The primary outcome was to detect DCI-related cerebral infarction, and the secondary outcome was the functional outcome at hospital discharge according to the modified Rankin scale (mRs). Univariate and multivariate logistic regression models were employed.

RESULTS

A total of 212 patients (71.7% female, mean age 52.7 ± 12.8) were included. Sixty-nine patients were classified as VASOGRADE-Green (32.5%), 98 patients as VASOGRADE-Yellow (46.9%), and 45 patients as VASOGRADE-Red (20.6%). DCI-related infarction was present in 39 patients (18.9%). The proportions of patients in the VASOGRADE-Green, VASOGRADE-Yellow, and VASOGRADE-Red categories with DCI-related infarction were 7.7, 61.5, and 30.8%, respectively. After a multivariable analysis including age, sex, aneurysm location, and the VASOGRADE classification as variables, both VASOGRADE-Yellow and VASOGRADE-Red were independently associated with DCI-related infarction (odds ratio [OR] 7.69, 95% confidence interval [CI] 2.13-27.8, and OR 8.07, 95% CI 2.03-32.11, respectively) and unfavorable outcome (OR 4.16, 95% CI 1.33-13.03, and OR 25.57, 95% CI 4.45-147.1, respectively). The VASOGRADE discrimination performance for DCI-related infarction (area under the receiver operating characteristic curve) was 0.67 ± 0.04 (95% CI 0.58-0.75; p = 0.001). VASOGRADE-Red had 97.5% specificity for predicting an unfavorable mRs score at discharge (95% CI 92.8-99.5%). Conversely, VASOGRADE-Green had an excellent specificity for predicting favorable outcome at discharge (mRs score 0-2, 95% CI 82.6-95.5%).

CONCLUSIONS

In conclusion, in a multiethnic cohort of patients with aSAH, VASOGRADE-Green predicted the absence of DCI and good clinical outcome at discharge with very high specificity, and patients in this category might be selected for early intensive care unit (ICU) discharge, minimizing costs and medical complications associated with prolonged hospital stay. On the other hand, patients categorized as VASOGRADE-Yellow and VASOGRADE-Red were at the highest risk for DCI. They should, therefore, be selected as a priority for care in high-volume aSAH centers, being aggressively monitored for DCI at the ICU. Such stratification methods are crucial, especially in countries with low financial resources and high health care services demand.

Utility of automated MRI perfusion (RAPID) with or without MR angiography for detection of angiographic vasospasm after aneurysmal subarachnoid hemorrhage

Delayed cerebral ischemia (DCI) is a major etiology of poor neurologic outcomes after aneurysmal subarachnoid hemorrhage (aSAH). Although the development of DCI is certainly multifactorial, the presence of vasospasm is strongly correlated with it. Cerebral angiography remains the gold standard for evaluation of vasospasm, though it is not always practical or cost-effective. In this study, the authors assess the utility of automated MRI Perfusion imaging, with or without MR Angiography (MRA), as a confirmatory tool for suspected angiographic vasospasm. All patients admitted to a single institution with aneurysmal subarachnoid hemorrhage between January 2014 and February 2020 and who underwent MR Perfusion imaging with or without MRA for suspected vasospasm no >24 h prior to an angiogram were identified. 43 subjects were identified. 29 of these patients (67%) underwent simultaneous MRA. 25 patients (53%) received intra-arterial treatment for symptomatic vasospasm. The sensitivity, specificity, PPV, and NPV of MR Perfusion were 43%, 82%, 53%, and 75% for any angiographic vasospasm and 57%, 81%, 42%, and 89% for treated vasospasm. The sensitivity, specificity, PPV, and NPV of MR Perfusion in conjunction with MRA were 61%, 81%, 59%, and 82% for any angiographic vasospasm and 62%, 74%, 35%, and 89% for treated vasospasm. The sensitivity, specificity, PPV, and NPV of transcranial Dopplers (TCDs) in these patients were 35%, 93%, 71%, and 75% for angiographic vasospasm and 42%, 90%, 47%, and 88% for treated vasospasm. Automated MR Perfusion imaging demonstrated relatively low sensitivity and PPV for detection of angiographic and treated vasospasm in this subset of patients after 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.

Transcranial Doppler Velocities and Angiographic Vasospasm after SAH: A Diagnostic Accuracy Study

BACKGROUND AND PURPOSE

After aneurysmal SAH, transcranial Doppler is commonly used to monitor cerebral vasospasm. The diagnostic accuracy of transcranial Doppler flow velocity values in detecting angiographic vasospasm in patients requiring urgent endovascular intervention has not been established.

MATERIALS AND METHODS

We performed a retrospective analysis of a consecutive series of patients with aneurysmal SAH who underwent transcranial Doppler (index test) within 24 hours of conventional angiography (reference test). The judgment of 33%, 50%, and 66% degree of vessel narrowing on angiography was independently established by multiple neuroendovascular clinicians. Vessel-specific per-segment and per-patient transcranial Doppler velocities were studied using receiver operating characteristic curves, the Youden index, and minimal acceptable sensitivity models. Optimal mean flow-velocity thresholds were explored to calculate sensitivity and specificity using a per-patient judgment of vasospasm of at least 50% angiographic narrowing in any large arterial segment except A1.

RESULTS

In 221 patients, vasospasm was found in 15%, 8%, and 4% of arteries when the degree of reference angiographic luminal narrowing was 33%, 50%, and 66%, respectively. Mean flow velocities were significantly higher in vasospastic segments (P = . 001), but per-segment exploratory analyses yielded unsound mean flow velocity thresholds. The Youden and minimal acceptable sensitivity models proposed mean flow velocity thresholds of approximately 160 cm/s for the anterior circulation and 80 cm/s for the posterior circulation in the per-patient diagnosis of angiographic vasospasm (≥50%), yielding a sensitivity of 80%-90% (95% CI, 0.77-0.96), but with a corresponding specificity of 50% (95% CI, 0.40-0.56).

CONCLUSIONS

In this study, a threshold transcranial Doppler mean flow-velocity value that would accurately diagnose ≥50% angiographic vasospasm remained elusive.

Cerebral vasospasm in children with subarachnoid hemorrhage: frequency, diagnosis, and therapeutic management

BACKGROUND

The present study explores the frequency, diagnostic approach, and therapeutic management of cerebral vasospasm in a cohort of children with moderate-to-severe traumatic and nontraumatic subarachnoid hemorrhage (SAH).

METHODS

This was a single-center retrospective study performed over a 10-year period, from January 2010 to December 2019. Children aged from one month to 18 years who were admitted to the pediatric or adult intensive care unit with a diagnosis of SAH were eligible. Cerebral vasospasm could be suspected by clinical signs or transcranial Doppler (TCD) criteria (mean blood flow velocity > 120 cm/s or an increase in mean blood flow velocity by > 50 cm/s within 24 h) and then confirmed on cerebral imaging (with a reduction to less than 50% of the caliber of the cerebral artery).

RESULTS

Eighty patients aged 8.6 years (3.3-14.8 years, 25-75th centiles) were admitted with an initial Glasgow Coma Scale score of 8 (4-12). SAH was nontraumatic in 21 (26%) patients. A total of 14/80 patients (18%) developed cerebral vasospasm on brain imaging on day 6 (5-10) after admission, with a predominance of nontraumatic SAH (12/14). The diagnosis of cerebral vasospasm was suspected on clinical signs and/or significant temporal changes in TCD monitoring (7 patients) and then confirmed on cerebral imaging. Thirteen of 14 patients with vasospasm were successfully treated using a continuous intravenous infusion of milrinone. The Pediatric Cerebral Performance Category score at discharge from the intensive care unit was comparable between children with vasospasm (score of 2 [1-4]) vs. children without vasospasm (score of 4 [2-4]) (p = 0.09).

CONCLUSIONS

These findings indicate that cerebral vasospasm exists in pediatrics, particularly after nontraumatic SAH. The use of TCD and milrinone may help in the diagnostic and therapeutic management of cerebral vasospasm.

Transcranial Dopplers Revisited: Development of Novel Markers for Cerebral Vasospasm After Aneurysmal Subarachnoid Hemorrhage

Background

Cerebral vasospasm has been monitored by conventional angiography or transcranial Doppler (TCD). While angiography is the most accurate and reliable method for detection, TCDs are a noninvasive alternative to monitor onset and resolution of vasospasm. We aim to determine whether alternative TCD parameters rather than Lindegaard ratio lead to an improved method to diagnose and potentially prevent cerebral vasospasm.

Methods

A total of 103 consecutive patients with subarachnoid hemorrhage (SAH) were retrospectively reviewed and TCD studies were performed during the first 14 days post-bleed or longer if indicated. Multivariate logistic regression models were developed using significant univariate characteristics. Receiver operating characteristic (ROC) curves evaluated the mean middle cerebral artery (MCA), peak systolic MCA (PSV MCA), and end diastolic MCA (EDV MCA) velocities as well as ratios when compared to the ipsilateral extracranial internal carotid artery (ICA). The area under the curve was calculated to compare accuracy for symptomatic vasospasm.

Results

Thirteen patients (12.6%) were observed to develop cerebral vasospasm. Aneurysm location (p = 0.51), Hunt and Hess grade (p = 0.44), Fischer grade (p = 0.87), comorbidities, age (p = 0.67), or gender (p = 0.41) did not appear to have any effect in predicting the presence of vasospasm. ROC curves demonstrated that MCA EDV appeared to be slightly better compared to MCA velocity in predicting symptomatic vasospasm. PSV MCA/extracranial ICA and the EDV MCA/extracranial ICA ratios appeared to be an improvement to the Lindegaard ratio in the prediction of symptomatic vasospasm.

Conclusion

The utility of peak systolic and end diastolic velocities, instead of the classically referenced mean velocities and Lindegaard ratio, may improve diagnostic sensitivity of cerebral vasospasm after subarachnoid hemorrhage.

Role of serum biomarkers and transcranial Doppler in predicting cerebral vasospasm after aneurysmal subarachnoid hemorrhage

Background

Aneurysmal subarachnoid hemorrhage (aSAH) can have serious consequences related to vasospasm and delayed cerebral ischemia (DCI). Serum biomarkers have emerged as a promising assessment tool to facilitate earlier diagnosis of cerebral vasospasm (CV) and to identify pre-clinical vessel narrowing.

Objectives

Our aim was to detect the predictive value of serum biomarkers such as von Willebrand factor (vWF), vascular endothelial growth factor (VEGF) and matrix metalloproteinase9 (MMP-9) in CV after aSAH.

Subjects and methods

Thirty five patients with recent aSAH were included. Patients were divided into two groups; 19 patients (CV group) and 16 patients (non-CV group). The CV group was further subdivided into 9 symptomatic (DCI) and 10 asymptomatic patients. All patients underwent transcranial Doppler (TCD) evaluations three times a week for 2 weeks measuring the mean flow velocities. Serum level of vWF, MMP-9, and VEGF were assessed twice (at onset and within 2 weeks).

Results

A statistically significant increase in serum biomarker levels was found in the CV group. Cutoff value for vWF, MMP-9, and VEGF were > 4985 ng/ml, > 495 ng/ml, and > 184 pg/ml, respectively. Statistically significant positive correlations were found between serum levels of biomarkers and degree of vasospasm. No difference was found in the biomarkers between symptomatic CV and asymptomatic CV.

Conclusion

Serum biomarkers are a reliable tool to predict CV following aSAH, their levels reflect the severity of vascular vasospasm, yet, they cannot predict DCI. TCD has a strong role in early detection, monitoring of post subarachnoid vasospasm and successfully capturing asymptomatic DCI.

Angioplasty with the scepter C dual lumen balloon catheter and postprocedural result evaluation in patients with subarachnoid hemorrhage related vasospasms

BACKGROUND

Delayed cerebral ischemia is one of the leading causes of death and disability in patients with subarachnoid hemorrhage (SAH). Transluminal balloon angioplasty (TBA) is a therapeutic option for vasospasms affecting proximal intracranial arteries.

METHODS

Aim of this study was to report our experience using the Scepter C balloon catheter in the treatment of cerebral vasospasms due to SAH and evaluate the postprocedural result with the iFlow tool. We reviewed cases of patients treated at our hospital from 2014 to 2018. Patients were screened with transcranial doppler sonography (TCD) and multimodal computed tomography. In case of significant vasospasms, patients were transferred to the angiography suite and treated. We used the iFlow tool to quantify and evaluate the angiographic results by measuring and comparing peak density values on angiograms before and after the mechanical dilation.

RESULTS

The use of the Scepter C balloon catheter was feasible in all cases. Vasospasms of the anterior cerebral artery were treated in ten cases. We didn't observe complications or vasospasm recurrences of the treated arteries. The temporal difference between distal vessels and the proximal reference vessel was significantly reduced from a mean of 53%, prior to dilatation, to 26% after the treatment. The difference between pre-dilatation and post-dilatation values was statistically significant for the anterior circulation at the proximal as well as at the distal vessels.

CONCLUSIONS

We successfully treated endovascularly patients suffering from cerebral vasospasms refractory to medical treatment using the Scepter C balloon catheter. We didn't observe any complications. The therapeutic effect could be easily and reliably assessed with the iFlow tool.

Role of ABO blood type in delayed cerebral ischemia onset and clinical outcomes after aneurysmal subarachnoid hemorrhage in an ethnic minority urban population

BACKGROUND

In recent years, the role of ABO blood type moved into focus through the discovery of different hemostaseologic properties with importance in many diseases including subarachnoid hemorrhage (SAH). However, the role of ABO blood type in delayed cerebral ischemia (DCI) onset, clinical progress, and outcome after SAH is to date largely unexplored. Our aim was to explore the role of ABO blood group in DCI and clinical outcomes after aneurysmal SAH (aSAH).

METHODS

A retrospective analysis was made with data collected from patients who presented aSAH at our single- academic center from 2015 to 2018. We included demographic, clinical, and imaging variables in the univariate analysis and in the subsequent multivariate analysis.

RESULTS

A total of 204 patients were included in this study. About 17.9% of "O" type patients developed a DCI while DCI was reported in only 8.2% of non-O type patients (P = 0.04). "O" type was an independent risk after in the logistic regression after adjusting for significant factors in the univariate analysis (OR=2.530, 95% CI: 1.040- 6.151, P = 0.41). Compared to "non-O" type patients, "O" type patients had a trend to have poorer outcomes at discharge (25.5% vs. 21.3%, P = 0.489) and at 12-18 months (21.1% vs. 19.5%, P = 0.795). However, there were no significant differences.

CONCLUSION

Our study evidenced that patients with "O" blood type have higher risk of DCI onset after aSAH. Although these findings need to be confirmed, they may aid to improve DCI prevention and outcome predictions.

Transcranial Doppler in the Diagnosis of Cerebral Vasospasm: An Updated Meta-Analysis

OBJECTIVES

To evaluate the performance of transcranial Doppler and transcranial color-coded duplex Doppler in patients with cerebral vasospasm due to aneurysm rupture. Angiography was considered as the gold standard comparator.

DATA SOURCES

Search in MEDLINE, Embase, and Central from January 2001 to October 2017, without language restriction. Bibliographies of retrieved articles were screened for additional studies.

STUDY SELECTION

Randomized studies comparing transcranial Doppler or transcranial color-coded duplex Doppler with angiography in adults.

DATA EXTRACTION

Data were extracted independently by several investigators. Sensitivity and specificity were combined across studies using a bivariate model. Preferred Reporting Items for Systematic Reviews and Meta-Analyses was used for reporting and Quality Assessment of Diagnostic Accuracy Studies-2 for quality assessment.

DATA SYNTHESIS

We included 18 studies. Fifteen tested transcranial Doppler. For the middle cerebral artery (10 studies, 1,408 tests), the pooled sensitivity was 66.7% (95% CI, 55.9-75.9) and specificity was 89.5% (80.3-94.7). Three studies (278 tests) tested transcranial color-coded duplex Doppler for the middle cerebral artery. The pooled sensitivity was 81.5% (66.0-90.0), and specificity was 96.6% (93.0-98.0). For an arbitrarily chosen prevalence of vasospasm of 70%, positive and negative predictive values were 93.7% (88.9-96.6) and 53.4% (46.7-60.9) for transcranial Doppler and 98.2% (96.4-99.1) and 69.1% (56.1-80.9) for transcranial color-coded duplex Doppler.

CONCLUSIONS

Assuming a high prevalence of vasospasm of the middle cerebral artery, both transcranial Doppler and transcranial color-coded duplex Doppler are likely to detect it, but neither is useful to exclude it. There is no convincing evidence that the accuracy of transcranial color-coded duplex Doppler is any better than that of transcranial Doppler. For arteries other than middle cerebral artery, there is a lack of evidence of the usefulness of transcranial Doppler.

Endovascular treatment of cerebral vasospasm after subarachnoid hemorrhage

Objective

Delayed cerebral ischemia (DCI) is strongly associated with poor outcome after subarachnoid hemorrhage (SAH). Cerebral vasospasm is a major contributor to DCI and requires special attention. To evaluate the effect of vasospasm management on SAH outcome, we performed a pooled analysis of 2 observational SAH cohorts.

Materials

Data from 2 institutional databases with consecutive patients with SAH treated between 2005 and 2012 were pooled. The effect of 2 institutional standards of conservative and endovascular vasospasm treatment (EVT) on the rates of DCI (new cerebral infarcts not visible on the post-treatment imaging) and unfavorable outcome (modified Rankin Scale score >2) at 6 months follow-up was analyzed.

Results

The final analysis included 1,057 patients with SAH. There was no difference regarding demographic (age and sex), clinical (Hunt & Hess grades, acute hydrocephalus, treatment modality, and infections), and radiographic (Fisher grades and aneurysm location) characteristics of the populations. However, there was a significant difference in the rate (24.4% [121/495] vs 14.4% [81/562], p < 0.0001) and timing (first treatment on day 6 vs 8.9 after SAH, p < 0.0001) of EVT. The rates of DCI (20.8% vs 29%, p = 0.0001) and unfavorable outcome (44% vs 50.6%, p = 0.04) were lower in the cohort with more frequent and early EVT. Multivariate analysis confirmed independent effect of EVT standard on DCI risk and outcome.

Conclusions

A preventive strategy utilizing frequent and early EVT seems to reduce the risk of DCI in patients with SAH and improve their functional outcome. We recommend prospective evaluation of the value of preventive EVT strategy on SAH.

Classification of evidence

This study provides Class III evidence that for patients with SAH, a frequent and early EVT to treat vasospasm reduces the risk of DCI and improves functional outcome.

Clinical prediction of delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage

OBJECTIVE

The aim of this study was to derive a clinically applicable decision rule using clinical, radiological, and laboratory data to predict the development of delayed cerebral ischemia (DCI) in aneurysmal subarachnoid hemorrhage (aSAH) patients.

METHODS

Patients presenting over a consecutive 9-year period with subarachnoid hemorrhage (SAH) and at least 1 angiographically evident aneurysm were included. Variables significantly associated with DCI in univariate analysis underwent multivariable logistic regression. Using the beta coefficients, points were assigned to each predictor to establish a scoring system with estimated risks. DCI was defined as neurological deterioration attributable to arterial narrowing detected by transcranial Doppler ultrasonography, CT angiography, MR angiography, or catheter angiography, after exclusion of competing diagnoses.

RESULTS

Of 463 patients, 58% experienced angiographic vasospasm with an overall DCI incidence of 21%. Age, modified Fisher grade, and ruptured aneurysm location were significantly associated with DCI. This combination of predictors had a greater area under the receiver operating characteristic curve than the modified Fisher grade alone (0.73 [95% CI 0.67-0.78] vs 0.66 [95% CI 0.60-0.71]). Patients 70 years or older with modified Fisher grade 0 or 1 SAH and a posterior circulation aneurysm had the lowest risk of DCI at 1.2% (0 points). The highest estimated risk was 38% (17 points) in patients 40-59 years old with modified Fisher grade 4 SAH following rupture of an anterior circulation aneurysm.

CONCLUSIONS

Among patients presenting with aSAH, this score-based clinical prediction tool exhibits increased accuracy over the modified Fisher grade alone and may serve as a useful tool to individualize DCI risk.

Radiological scales predicting delayed cerebral ischemia in subarachnoid hemorrhage: systematic review and meta-analysis

PURPOSE

Delayed cerebral ischemia (DCI) is a severe complication of aneurysmal subarachnoid hemorrhage (aSAH). The extent of subarachnoid blood is a strong predictor of DCI and is frequently estimated with the Fisher scale, modified Fisher scale, or Hijdra sum score. It is unclear which scale has the strongest association with clinical DCI. To evaluate this, we performed a systematic review of the literature.

METHODS

We performed a MEDLINE and EMBASE search from 1980 to 20th of June 2017. Radiological grade and occurrence of clinical DCI were extracted along with odds ratios (ORs) for DCI. When possible, pooled ORs with 95% confidence intervals were calculated per grade increase on the radiological scale.

RESULTS

Fifty-three studies were included. The Fisher scale was significantly associated with DCI in 62% of the studies compared to 88-100% for the other scales. In studies using the Fisher scale, Fisher 3 had the strongest association with DCI (pooled OR 3.21 (1.87-5.49)). In studies using the modified Fisher score, DCI occurred most frequently (42%) in modified Fisher 4. No pooled OR could be calculated for the other scales.

CONCLUSION

The Fisher scale, modified Fisher scale, and Hijdra sum score are all associated with clinical DCI. The risk of DCI, however, does not increase with increasing Fisher grade as opposed to the modified Fisher scale. Furthermore, the modified Fisher scale was more commonly significantly associated with DCI than the Fisher scale, which may advocate using the modified Fisher in future SAH-related studies.

Does Neurosurgical Clipping or Endovascular Coiling Lead to More Cases of Delayed Hydrocephalus in Patients with Subarachnoid Hemorrhage?

Objective

We investigated whether clipping or endovascular treatment (EVT) can reduce the incidence of delayed hydrocephalus. We also investigated whether additional procedures, namely lumbar drainage and extra-ventricular drainage (EVD), decrease the incidence of delayed hydrocephalus in patients with subarachnoid hemorrhage (SAH).

Materials and Methods

One-hundred and fifty-two patients who had undergone an operation for SAH were enrolled in this study. Clinical data, radiological data, and procedural data were investigated. Procedural data included the operating technique (clipping vs. EVT) and the use of additional procedures (no procedure, lumbar drainage, or EVD). Delayed hydrocephalus was defined as a condition in which the Evan's index was 0.3 or higher, as assessed using brain computed tomography more than 2 weeks after surgery, requiring shunt placement due to neurological deterioration.

Results

Of the 152 patients, 45 (29.6%) underwent surgical clipping and 107 (70.4%) underwent EVT. Twenty-five (16.4%) patients developed delayed hydrocephalus. Age (p = 0.019), procedure duration (p = 0.004), and acute hydrocephalus (p = 0.030) were significantly correlated with the incidence of delayed hydrocephalus. However, the operation technique (p = 0.593) and use of an additional procedure (p = 0.378) were not significantly correlated with delayed hydrocephalus incidence.

Conclusion

No significant difference in the incidence of delayed hydrocephalus was associated with operation technique or use of an additional procedure in patients with SAH. However, delayed hydrocephalus was significantly correlated with old age, long procedural duration, and acute hydrocephalus. Therefore, we recommend that additional procedures should be discontinued as soon as possible.

The effect of anesthetic agents on cerebral vasospasms after subarachnoid hemorrhage: A retrospective study

Cerebral vasospasm is the most important cause of morbidity after an aneurysm clipping in the early postoperative period. The aim of this retrospective study was to evaluate whether the incidence of vasospasms differs when using propofol or desflurane for an emergent aneurysm clipping.The data from 102 patients (50 in the propofol group, 52 in the desflurane group) were analyzed. The occurrence of vasospasm based on daily transcranial Doppler, angiography, and cerebral infarction during 14 days after surgery were compared by anesthetic agents. Postoperative data including Glasgow Coma Scale (GCS) score on day 14 after surgery, and the Glasgow Outcome Scale (GOS) score at 3 months were documented.Patients that intraoperatively received propofol for anesthesia maintenance, had higher incidence of transcranial Doppler (TCD)-evident vasospasm than those that received desflurane (54% vs 30.8%, P = .027). The occurrence of TCD-evident vasospasm was still higher (odds ratio: 2.84; 95% confidence interval: 1.12-7.20) in the propofol group than in the desflurane group after adjusting for confounding factors. However, the incidence of angiographic vasospasm, cerebral infarction, and interventions to treat cerebral vasospasms were similar between both groups. GCS score on day 14 after surgery and the GOS score at 3 months were similar between groups.No effect of anesthetic agents on angiographic vasospasm, cerebral infarction, or clinical outcome was observed, whereas desflurane anesthesia was associated with a lower incidence of TCD-evident vasospasms compared to propofol anesthesia. Our study provides a basis for further randomized controlled studies in a larger patient population to clarify the effects of anesthetic agents on the occurrence of cerebral vasospasms.

Early Hemodynamic Changes Based on Initial Color-Coding Angiography as a Predictor for Developing Subsequent Symptomatic Vasospasm After Aneurysmal Subarachnoid Hemorrhage

INTRODUCTION

Prediction of vasospasm after aneurysmal subarachnoid hemorrhage (aSAH) remains imperfect and currently relies on clinical and radiographic characteristics. Whether early hemodynamic changes may refine risk stratification for delayed vasospasm (DV) after aSAH was analyzed.

METHODS

Patients with aSAH (n = 53) and a control group with unruptured intracranial aneurysms (UIA) (n = 12) with initial color-coding angiography at admission were included in this study (n = 65). Clinical and radiologic data were collected, and uni- and multivariate analysis was used to correlate the occurrence of DV (manifesting clinically or detected with transcranial Doppler or angiography) with hemodynamic features of the initial angiography including Tmax and mean transit times (MTTs).

RESULTS

In the aSAH patient cohort, 37 of 53 patients with aSAH (70%) developed DV. After we controlled for the effects of age, Hunt and Hess grade, and modified Fisher grade, patients with DV had a shorter mean region of interest peak time (Tmax) of the anterior cerebral artery A2 segment (P = 0.036) and the middle cerebral artery M1 (P = 0.045) and M3 (P = 0.013) segments. Mean MTTs between internal carotid artery to middle cerebral artery M3 segment (P = 0.026) was also significantly shorter in patients with DV when compared with controls.

CONCLUSIONS

Tmax and MTT on angiography within 48 hours of aneurysm rupture before treatment provide an early quantitative assessment in patients with aSAH and in this small study were predictive for the development of subsequent symptomatic DV. Early identification of patients with aSAH at greatest risk of DV may ameliorate clinical outcome through timely, selective implementation of aggressive prophylactic therapy to prevent the effects of DV.

Blood free Radicals Concentration Determined by Electron Paramagnetic Resonance Spectroscopy and Delayed Cerebral Ischemia Occurrence in Patients with Aneurysmal Subarachnoid Hemorrhage

Pathophysiology of delayed cerebral ischemia and cerebral vasospasm following aneurysmal subarachnoid hemorrhage is still poorly recognized, however free radicals are postulated as one of the crucial players. This study was designed to scrutinize whether the concentration of free radicals in the peripheral venous blood is related to the occurrence of delayed cerebral ischemia associated with cerebral vasospasm. Twenty-four aneurysmal subarachnoid hemorrhage patients and seven patients with unruptured intracranial aneurysm (control group) have been studied. Free radicals in patients’ blood have been detected by the electron paramagnetic resonance (CMH.HCl spin probe, 150 K, ELEXSYS E500 spectrometer) on admission and at least 72 h from disease onset. Delayed cerebral ischemia monitoring was performed by daily neurological follow-up and transcranial color coded Doppler. Delayed cerebral ischemia observed in six aneurysmal subarachnoid hemorrhage patients was accompanied by cerebral vasospasm in all six cases. No statistically significant difference in average free radicals concentration between controls and study subgroups was noticed on admission (p = .3; Kruskal–Wallis test). After 72 h free radicals concentration in delayed cerebral ischemia patients (3.19 ± 1.52 mmol/l) differed significantly from the concentration in aneurysmal subarachnoid hemorrhage patients without delayed cerebral ischemia (0.65 ± 0.37 mmol/l) (p = .012; Mann–Whitney test). These findings are consistent with our assumptions and seem to confirm the role of free radicals in delayed cerebral ischemia development. Preliminary results presented above are promising and we need perform further investigation to establish whether blood free radicals concentration may serve as the biomarker of delayed cerebral ischemia associated with cerebral vasospasm.

The Effect of a Single dose Dantrolene in Patients with Vasospasm Following Aneurysmal Subarachnoid Hemorrhage

Background:

Cerebral vasospasm is a prolonged, occasionally severe, but reversible narrowing of the cerebral arteries that begins 3 to 5 days after the hemorrhage becomes maximal at 14 days. This study is designed to evaluate the effect of dantrolene on the reduction of vasospasm following aneurysmal subarachnoid hemorrhage (SAH).

Materials and Methods:

This randomized controlled clinical trial was conducted on 32 patients with proven aneurysms in AL-Zahra hospital during 2011-2013. They were randomly divided into two groups. In all patients, daily transcranial Doppler sonography was performed and as soon as the diagnosis of vasospasm onset in the first group, in addition to conventional treatment of vasospasm 2.5 mg/kg Dantrolene infusion within 60 minutes and while the blood pressure and heart rate of patient monitored, and arterial flow velocity changes such as PSV and MFV were measured by transcranial Doppler sonography in 45, 90 and 135 minutes. Data was analyzed by SPSS 22 and Chi-square, Student t, Mann-Whitney and ANOVA tests with repeated observations.

Results:

There was no significant difference in the site of the aneurysm in the two groups. The mean of PSV index prior to treatment and the 45^th minute was not different but at 90^th and 135^th minutes it was significantly lower in the Dantrolene receiving group (P < 0.05). The mean of MFV index prior to intervention and in the 45^th minute was not different between two groups, but at 90^th and 135^th minutes was significantly lower in the target group

Conclusion:

Using dantrolene in patients with artery vasospasm significantly reduced artery spasm and increased the patient recovery.

Brain Multimodality Monitoring: A New Tool in Neurocritical Care of Comatose Patients

Neurocritical care patients are at risk of developing secondary brain injury from inflammation, ischemia, and edema that follows the primary insult. Recognizing clinical deterioration due to secondary injury is frequently challenging in comatose patients. Multimodality monitoring (MMM) encompasses various tools to monitor cerebral metabolism, perfusion, and oxygenation aimed at detecting these changes to help modify therapies before irreversible injury sets in. These tools include intracranial pressure (ICP) monitors, transcranial Doppler (TCD), Hemedex™ (thermal diffusion probe used to measure regional cerebral blood flow), microdialysis catheter (used to measure cerebral metabolism), Licox™ (probe used to measure regional brain tissue oxygen tension), and continuous electroencephalography. Although further research is needed to demonstrate their impact on improving clinical outcomes, their contribution to illuminate the black box of the brain in comatose patients is indisputable. In this review, we further elaborate on commonly used MMM parameters, tools used to measure them, and the indications for monitoring per current consensus guidelines.

Multimodal neurologic monitoring

Neurocritical care has two main objectives. Initially, the emphasis is on treatment of patients with acute damage to the central nervous system whether through infection, trauma, or hemorrhagic or ischemic stroke. Thereafter, attention shifts to the identification of secondary processes that may lead to further brain injury, including fever, seizures, and ischemia, among others. Multimodal monitoring is the concept of using various tools and data integration to understand brain physiology and guide therapeutic interventions to prevent secondary brain injury. This chapter will review the use of electroencephalography, intracranial pressure monitoring, brain tissue oxygenation, cerebral microdialysis and neurochemistry, near-infrared spectroscopy, and transcranial Doppler sonography as they relate to neuromonitoring in the critically ill. The concepts and design of each monitor, in addition to the patient population that may most benefit from each modality, will be discussed, along with the various tools that can be used together to guide individualized patient treatment options. Major clinical trials, observational studies, and their effect on clinical outcomes will be reviewed. The future of multimodal monitoring in the field of bioinformatics, clinical research, and device development will conclude the chapter.

Transcranial Doppler ultrasonography: From methodology to major clinical applications

Non-invasive Doppler ultrasonographic study of cerebral arteries [transcranial Doppler (TCD)] has been extensively applied on both outpatient and inpatient settings. It is performed placing a low-frequency (≤ 2 MHz) transducer on the scalp of the patient over specific acoustic windows, in order to visualize the intracranial arterial vessels and to evaluate the cerebral blood flow velocity and its alteration in many different conditions. Nowadays the most widespread indication for TCD in outpatient setting is the research of right to left shunting, responsable of so called “paradoxical embolism”, most often due to patency of foramen ovale which is responsable of the majority of cryptogenic strokes occuring in patients younger than 55 years old. TCD also allows to classify the grade of severity of such shunts using the so called “microembolic signal grading score”. In addition TCD has found many useful applications in neurocritical care practice. It is useful on both adults and children for day-to-day bedside assessment of critical conditions including vasospasm in subarachnoidal haemorrhage (caused by aneurysm rupture or traumatic injury), traumatic brain injury, brain stem death. It is used also to evaluate cerebral hemodynamic changes after stroke. It also allows to investigate cerebral pressure autoregulation and for the clinical evaluation of cerebral autoregulatory reserve.

Brain Multimodality Monitoring: Updated Perspectives

The challenges posed by acute brain injury (ABI) involve the management of the initial insult in addition to downstream inflammation, edema, and ischemia that can result in secondary brain injury (SBI). SBI is often subclinical, but can be detected through physiologic changes. These changes serve as a surrogate for tissue injury/cell death and are captured by parameters measured by various monitors that measure intracranial pressure (ICP), cerebral blood flow (CBF), brain tissue oxygenation (PbtO2), cerebral metabolism, and electrocortical activity. In the ideal setting, multimodality monitoring (MMM) integrates these neurological monitoring parameters with traditional hemodynamic monitoring and the physical exam, presenting the information needed to clinicians who can intervene before irreversible damage occurs. There are now consensus guidelines on the utilization of MMM, and there continue to be new advances and questions regarding its use. In this review, we examine these recommendations, recent evidence for MMM, and future directions for MMM.

External validation of the Practical Risk Chart for the prediction of delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage

OBJECTIVE Delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH) occurs in approximately 30% of patients. The Practical Risk Chart was developed to predict DCI based on admission characteristics; the authors seek to externally validate and critically appraise this prediction tool. METHODS A prospective cohort of aSAH patients was used to externally validate the previously published Practical Risk Chart. The model consists of 4 variables: clinical condition on admission, amount of cisternal and intraventricular blood on CT, and age. External validity was assessed using logistic regression. Model discrimination was evaluated using the area under the receiver operating characteristic curve (AUC). RESULTS In a cohort of 125 patients with aSAH, the Practical Risk Chart adequately predicted DCI, with an AUC of 0.66 (95% CI 0.55-0.77). Clinical grade on admission and amount of intracranial blood on CT were the strongest predictors of DCI and clinical vasospasm. The best-fit model used a combination of the Hunt and Hess grade and the modified Fisher scale to yield an AUC of 0.76 (95% CI 0.675-0.85) and 0.70 (95% CI 0.602-0.8) for the prediction of DCI and clinical vasospasm, respectively. CONCLUSIONS The Practical Risk Chart adequately predicts the risk of DCI following aSAH. However, the best-fit model represents a simpler stratification scheme, using only the Hunt and Hess grade and the modified Fisher scale, and produces a comparable AUC.

Transcranial Doppler Ultrasound: Physical Principles and Principal Applications in Neurocritical Care Unit

Transcranial Doppler (TCD) ultrasonography is a noninvasive ultrasound study, which has been extensively applied on both outpatient and inpatient settings. It involves the use of a low-frequency (≤2 MHz) transducer, placed on the scalp, to insonate the basal cerebral arteries through relatively thin bone windows and to measure the cerebral blood flow velocity and its alteration in many different conditions. In neurointensive care setting, TCD is useful for both adults and children for day-to-day bedside assessment of critical conditions including vasospasm in subarachnoid hemorrhage, traumatic brain injury, acute ischemic stroke, and brain stem death. It also allows to investigate the cerebrovascular autoregulation in setting of carotid disease and syncope. In this review, we will describe physical principles underlying TCD, flow indices most frequently used in clinical practice and critical care applications in Neurocritical Unit care.

Early whole-brain CT perfusion for detection of patients at risk for delayed cerebral ischemia after subarachnoid hemorrhage

OBJECT This prospective study investigated the role of whole-brain CT perfusion (CTP) studies in the identification of patients at risk for delayed ischemic neurological deficits (DIND) and of tissue at risk for delayed cerebral infarction (DCI). METHODS Forty-three patients with aneurysmal subarachnoid hemorrhage (aSAH) were included in this study. A CTP study was routinely performed in the early phase (Day 3). The CTP study was repeated in cases of transcranial Doppler sonography (TCD)-measured blood flow velocity (BFV) increase of > 50 cm/sec within 24 hours and/or on Day 7 in patients who were intubated/sedated. RESULTS Early CTP studies revealed perfusion deficits in 14 patients, of whom 10 patients (72%) developed DIND, and 6 of these 10 patients (60%) had DCI. Three of the 14 patients (21%) with early perfusion deficits developed DCI without having had DIND, and the remaining patient (7%) had neither DIND nor DCI. There was a statistically significant correlation between early perfusion deficits and occurrence of DIND and DCI (p < 0.0001). A repeated CTP was performed in 8 patients with a TCD-measured BFV increase > 50 cm/sec within 24 hours, revealing a perfusion deficit in 3 of them (38%). Two of the 3 patients (67%) developed DCI without preceding DIND and 1 patient (33%) had DIND without DCI. In 4 of the 7 patients (57%) who were sedated and/or comatose, additional CTP studies on Day 7 showed perfusion deficits. All 4 patients developed DCI. CONCLUSIONS Whole-brain CTP on Day 3 after aSAH allows early and reliable identification of patients at risk for DIND and tissue at risk for DCI. Additional CTP investigations, guided by TCD-measured BFV increase or persisting coma, do not contribute to information gain.

Matched Cohort Analysis of the Effects of Limb Remote Ischemic Conditioning in Patients with Aneurysmal Subarachnoid Hemorrhage

Remote ischemic conditioning (RIC) is a powerful innate response to transient subcritical ischemia that protects against severe ischemic insults at distant sites. We have previously shown the safety and feasibility of limb RIC in aneurysmal subarachnoid hemorrhage (aSAH) patients, along with changes in neurovascular and cerebral metabolism. In this study, we aim to detect the potential effect of an established lower-limb conditioning protocol on clinical outcomes of aSAH patients. Neurologic outcome (modified Rankin Scale (mRS)) of patients enrolled in a prospective trial (RIPC-SAH) was measured. A matching algorithm was applied to identify control patients with aSAH from an institutional departmental database. RIC patients underwent four lower-limb conditioning sessions, consisting of four 5-min cycles per session over nonconsecutive days. Good functional outcome was defined as mRS of 0 to 2. The study population consisted of 21 RIC patients and 61 matched controls. There was no significant intergroup difference in age, gender, aneurysm location, clipping vs coiling, Fisher grades, Hunt and Hess grades, or vasospasm. RIC was independently associated with good outcome (OR 5.17; 95% confidence interval (CI) 1.21-25.02). RIC also showed a trend toward lower incidence of stroke (28.6 vs. 47.5%) and death (4.8 vs. 19.7%). Lower-limb RIC following aSAH appears to have a positive effect in the functional outcomes of patients with aSAH. While this effect is consistent with prior preclinical studies, future trials are necessary to conclusively evaluate the effects of RIC for aSAH.

A Review of the Effectiveness of Neuroimaging Modalities for the Detection of Traumatic Brain Injury

The incidence of traumatic brain injury (TBI) in the United States was 3.5 million cases in 2009, according to the Centers for Disease Control and Prevention. It is a contributing factor in 30.5% of injury-related deaths among civilians. Additionally, since 2000, more than 260,000 service members were diagnosed with TBI, with the vast majority classified as mild or concussive (76%). The objective assessment of TBI via imaging is a critical research gap, both in the military and civilian communities. In 2011, the Department of Defense (DoD) prepared a congressional report summarizing the effectiveness of seven neuroimaging modalities (computed tomography [CT], magnetic resonance imaging [MRI], transcranial Doppler [TCD], positron emission tomography, single photon emission computed tomography, electrophysiologic techniques [magnetoencephalography and electroencephalography], and functional near-infrared spectroscopy) to assess the spectrum of TBI from concussion to coma. For this report, neuroimaging experts identified the most relevant peer-reviewed publications and assessed the quality of the literature for each of these imaging technique in the clinical and research settings. Although CT, MRI, and TCD were determined to be the most useful modalities in the clinical setting, no single imaging modality proved sufficient for all patients due to the heterogeneity of TBI. All imaging modalities reviewed demonstrated the potential to emerge as part of future clinical care. This paper describes and updates the results of the DoD report and also expands on the use of angiography in patients with TBI.

Monitoring of cerebral blood flow and ischemia in the critically ill

Secondary ischemic injury is common after acute brain injury and can be evaluated with the use of neuromonitoring devices. This manuscript provides guidelines for the use of devices to monitor cerebral blood flow (CBF) in critically ill patients. A Medline search was conducted to address essential pre-specified questions related to the utility of CBF monitoring. Peer-reviewed recommendations were constructed according to the GRADE criteria based upon the available supporting literature. Transcranial Doppler ultrasonography (TCD) and transcranial color-coded duplex sonography (TCCS) are predictive of angiographic vasospasm and delayed ischemic neurological deficits after aneurysmal subarachnoid hemorrhage. TCD and TCCS may be beneficial in identifying vasospasm after traumatic brain injury. TCD and TCCS have shortcomings in identifying some secondary ischemic risks. Implantable thermal diffusion flowmetry (TDF) probes may provide real-time continuous quantitative assessment of ischemic risks. Data are lacking regarding ischemic thresholds for TDF or their correlation with ischemic injury and clinical outcomes.TCD and TCCS can be used to monitor CBF in the neurocritical care unit. Better and more developed methods of continuous CBF monitoring are needed to limit secondary ischemic injury in the neurocritical care unit.

Vasospasm on transcranial Doppler is predictive of delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

OBJECT The impact of transcranial Doppler (TCD) ultrasonography evidence of vasospasm on patient-centered clinical outcomes following aneurysmal subarachnoid hemorrhage (aSAH) is unknown. Vasospasm is known to lead to delayed cerebral ischemia (DCI) and poor outcomes. This systematic review and meta-analysis evaluates the predictive value of vasospasm on DCI, as diagnosed on TCD. METHODS MEDLINE, Scopus, the Cochrane trial register, and clinicaltrials.gov were searched through September 2014 using key words and the terms "subarachnoid hemorrhage," "aneurysm," "aneurysmal," "cerebral vasospasm," "vasospasm," "transcranial Doppler," and "TCD." Sensitivities, specificities, and positive and negative predictive values were pooled by a DerSimonian and Laird random-effects model. RESULTS Seventeen studies (n = 2870 patients) met inclusion criteria. The amount of variance attributable to heterogeneity was significant (I(2) > 50%) for all syntheses. No studies reported the impact of TCD evidence of vasospasm on functional outcome or mortality. TCD evidence of vasospasm was found to be highly predictive of DCI. Pooled estimates for TCD diagnosis of vasospasm (for DCI) were sensitivity 90% (95% confidence interval [CI] 77%-96%), specificity 71% (95% CI 51%-84%), positive predictive value 57% (95% CI 38%-71%), and negative predictive value 92% (95% CI 83%-96%). CONCLUSIONS TCD evidence of vasospasm is predictive of DCI with high accuracy. Although high sensitivity and negative predictive value make TCD an ideal monitoring device, it is not a mandated standard of care in aSAH due to the paucity of evidence on clinically relevant outcomes, despite recommendation by national guidelines. High-quality randomized trials evaluating the impact of TCD monitoring on patient-centered and physician-relevant outcomes are needed.

Toll-like Receptor 4 (TLR4) is Associated with Cerebral Vasospasm and Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage

In the present prospective study, the Toll-like receptor 4 (TLR4) levels on peripheral blood mononuclear cells (PBMCs) were investigated in 30 patients with aneurysmal subarachnoid hemorrhage (aSAH) and in 20 healthy controls (HCs). The relationship between TLR4 levels and the occurrence of cerebral vasospasm (CVS) was also analyzed. TLR4 expression level on cell surface of PBMCs on days 1, 3, and 7 after admission was determined by flow cytometry. Results showed that patients with aSAH presented a significantly higher TLR4 levels. For patients with Hunt-Hess grades IV–V, higher TLR4 levels were also observed; higher TLR4 levels have already been seen in patients developing CVS and/or delayed cerebral ischemia (DCI). Higher TLR4 levels were also associated with modified Fisher score, occurrence of dCVS, DCI, cerebral infarction (CT), and poor neurological functional recovery. Binary logistic regression analysis indicated that high TLR4 expression on blood monocytes was an independent predictive factor of the occurrence of dCVS, DCI, and poor neurological functional recovery. Taken together, TLR4 levels on PBMCs is significantly altered in the early stage of aSAH, especially in those patients experiencing CVS and DCI. Furthermore, higher TLR4 levels in the early stage of aSAH is also associated with the neurological function outcome. As far as we know, this is the first clinical study about TLR4's significance for patients with aSAH.

Cerebral Vasospasm: A Review

Cerebral vasospasm is a prolonged but reversible narrowing of cerebral arteries beginning days after subarachnoid hemorrhage. Progression to cerebral ischemia is tied mostly to vasospasm severity, and its pathogenesis lies in artery encasement by blood clot, although the complex interactions between hematoma and surrounding structures are not fully understood. The delayed onset of vasospasm provides a potential opportunity for its prevention. It is disappointing that recent randomized, controlled trials did not demonstrate that the endothelin antagonist clazosentan, the cholesterol-lowering agent simvastatin, and the vasodilator magnesium sulfate improve patient outcome. Minimizing ischemia by avoiding inadequate blood volume and pressure, administering the calcium antagonist nimodipine, and intervention with balloon angioplasty, when necessary, constitutes current best management. Over the past two decades, our ability to manage vasospasm has led to a significant decline in patient morbidity and mortality from vasospasm, yet it still remains an important determinant of outcome after aneurysm rupture.

Blood pressure changes after aneurysmal subarachnoid hemorrhage and their relationship to cerebral vasospasm and clinical outcome

OBJECTIVE

Cerebral vasospasm (VS) and resulting delayed ischemic brain injury constitute the most severe secondary complication after subarachnoid hemorrhage (SAH). Identification of early clinical predictors of developing vasospasm and poor outcome has remained a major challenge in neurointensive care medicine. Aim of the present study was analyze the relevance of spontaneous changes in blood pressures and their predictive value for predicting vasospasm as well as adverse clinical outcome.

METHODS

98 aneurysmal SAH patients were analyzed retrospectively. Patients were divided into two study groups: (1) VS+ (developing VS) and (2) VS- (not developing VS). Repeat-angiography was routinely performed on day 8 after SAH or earlier if clinical signs were suggestive for overt vasospasm. Systolic, diastolic and mean blood pressures were averaged hourly and plotted over time. Secondly, blood pressure (BP)-progression was analyzed with respect to clinical outcomes as assessed by the Glasgow outcome scale.

RESULTS

Mean, systolic, and diastolic blood pressure values progressed in both VS- and VS+ cohorts over time. However, as early as 4 days after SAH a significant dissociation of RR curves was observed between the groups with patients in the VS+ group displaying a significantly higher slope coefficient of blood pressure elevation. An increase of mean arterial pressure >20% within the first 4 days was predictive of developing vasospasm. Elevation of mean arterial blood pressure in the VS+ group was mainly attributable to changes in diastolic pressure. Elevation of mean arterial blood pressure >25% within the first week after SAH was associated with unfavorable outcome.

CONCLUSIONS

SAH leads to spontaneous and progressive elevations in mean arterial blood pressure. Vasospasm might be anticipated by identifying early elevations of mean arterial blood pressure. Finally, spontaneous elevations of mean arterial blood pressure correlate with poorer outcomes.

Reproduction of consistent pulse-waveform changes using a computational model of the cerebral circulatory system

Due to the inaccessibility of the cranial vault, it is difficult to study cerebral blood flow dynamics directly. A mathematical model can be useful to study these dynamics. The model presented here is a novel combination of a one-dimensional fluid flow model representing the major vessels of the circle of Willis (CoW), with six individually parameterized auto-regulatory models of the distal vascular beds. This model has the unique ability to simulate high temporal resolution flow and velocity waveforms, amenable to pulse-waveform analysis, as well as sophisticated phenomena such as auto-regulation. Previous work with human patients has shown that vasodilation induced by CO2 inhalation causes 12 consistent pulse-waveform changes as measured by the morphological clustering and analysis of intracranial pressure algorithm. To validate this model, we simulated vasodilation and successfully reproduced 9 out of the 12 pulse-waveform changes. A subsequent sensitivity analysis found that these 12 pulse-waveform changes were most affected by the parameters associated with the shape of the smooth muscle tension response and vessel elasticity, providing insight into the physiological mechanisms responsible for observed changes in the pulse-waveform shape.

Cerebral vasospasm after aneurysmal subarachnoid hemorrhage and traumatic brain injury

OPINION STATEMENT

Cerebral vasospasm (cVSP) consists of the vasoconstriction of large and small intracranial vessels which can lead to cerebral hypoperfusion, and in extreme cases, delayed ischemic deficits with stroke. While most commonly observed after aneurysmal subarachnoid hemorrhage (aSAH), cVSP can also occur after traumatic brain injury (TBI) as we have described in detail in this review. For the past decades, the research attention has focused on cVSP because of its association with delayed cerebral ischemia, which is the largest contributor of morbidity and mortality after aSAH. New discoveries in the cVSP pathophysiology involving multifactorial complex cascades and pathways pose new targets for therapeutic interventions in the prevention and treatment of cVSP. The goal of this review is to demonstrate the commonalities and differences in epidemiology and pathophysiology of both aSAH and TBI-associated cVSP, and highlight the more recently discovered pathways of cVSP. Finally, the latest cVSP surveillance methods and treatment options are illustrated.

Regional cerebral blood flow alterations in obstructive sleep apnea

Obstructive sleep apnea (OSA) is a condition characterized by upper airway muscle atonia with continued diaphragmatic efforts, resulting in repeated airway obstructions, periods of intermittent hypoxia, large thoracic pressure changes, and substantial shifts in arterial pressure with breathing cessation and resumption. The hypoxic exposure and hemodynamic changes likely induce the structural and functional deficits found in multiple brain areas, as shown by magnetic resonance imaging (MRI) procedures. Altered cerebral blood flow (CBF) may contribute to these localized deficits; thus, we examined regional CBF, using arterial spin labeling procedures, in 11 OSA (age, 49.1±12.2 years; 7 male) and 16 control subjects (42.3±10.2 years; 6 male) with a 3.0-Tesla MRI scanner. CBF maps were calculated, normalized to a common space, and regional CBF values across the brain quantified. Lowered CBF values emerged near multiple bilateral brain sites in OSA, including the corticospinal tracts, superior cerebellar peduncles, and pontocerebellar fibers. Lateralized, decreased CBF appeared near the left inferior cerebellar peduncles, left tapetum, left dorsal fornix/stria terminalis, right medial lemniscus, right red nucleus, right midbrain, and midline pons. Regional CBF values in OSA are significantly reduced in major sensory and motor fiber systems and motor regulatory sites, especially in structures mediating motor coordination; those reductions are often lateralized. The asymmetric CBF declines in motor regulatory areas may contribute to loss of coordination between upper airway and diaphragmatic musculature, and lead to further damage in the syndrome.

Evidence-based cerebral vasospasm surveillance

Subarachnoid hemorrhage related to aneurysmal rupture (aSAH) carries significant morbidity and mortality, and its treatment is focused on preventing secondary injury. The most common—and devastating—complication is delayed cerebral ischemia resulting from vasospasm. In this paper, the authors review the various surveillance technologies available to detect cerebral vasospasm in the days following aSAH. First, evidence related to the most common modalities, including transcranial doppler ultrasonography and computed tomography, are reviewed. Continuous electroencephalography and older instruments such as positron emission tomography, xenon-enhanced CT, and single-photon emission computed tomography are also discussed. Invasive strategies including brain tissue oxygen monitoring, microdialysis, thermal diffusion, and jugular bulb oximetry are examined. Lastly, near-infrared spectroscopy, a recent addition to the field, is briefly reviewed. Each surveillance tool carries its own set of advantages and limitations, and the concomitant use of multiple modalities serves to improve diagnostic sensitivity and specificity.

Radiation exposure in patients with subarachnoid hemorrhage: a quality improvement target

OBJECT

The care of patients with subarachnoid hemorrhage (SAH) has improved dramatically over the last decades. These gains are the result of improved microsurgical, endovascular, and medical management techniques. This intensive management subjects patients to multiple radiographic studies and thus increased radiation exposure. As greater understanding of the risks of radiation exposure develops, physicians must be better equipped to balance the need for optimal SAH management with the minimization of patient exposure to radiation from imaging studies. The goal in the current study was to determine if there is an opportunity for a reduction in radiation dose without a change in the quality of treatment in patients with SAH.

METHODS

A retrospective chart review of all patients hospitalized for SAH at the Brigham and Women's Hospital in the period from January 1, 2009, to August 31, 2010, was performed. The authors calculated cumulative and imaging study-specific radiation doses, determined the time of day that imaging studies were performed, and surveyed neurosurgeons regarding issues surrounding imaging-related radiation exposure.

RESULTS

The data for 77 patients were analyzed. The mean cumulative radiation dose during hospitalization was 2.76 Gy per patient (range 0.46-8.32 Gy). The mean radiation exposure from each CT, CT angiography (CTA), and angiography study was 0.08, 0.29, and 0.77 Gy (ranges 0.02-0.40, 0.15-0.99, and 0.11-4.36 Gy, respectively). Subgroup analysis of the top quartile of patients in terms of total radiation dose revealed a mean cumulative radiation dose of 4.78 Gy (range 3.42-8.32 Gy), mean cumulative number of CT and CTA scans of 14, and mean CT or CTA scan per day of 0.5 (maximum 0.8). Seventeen percent of the noncontrast head CT studies were performed just prior to morning rounds, more than double the 8% expected rate at random. Thirty-four percent of the repeat noncontrast head CTs did not show any change between scans, as documented on radiology reports. When surveyed, a majority of neurosurgeons incorrectly estimated the radiation dose typically received from CT, CTA, and angiography studies, and 65% asserted that radiation exposure is "not important" or only "somewhat important" when considering whether to order an imaging study.

CONCLUSIONS

Study findings suggested that patients with SAH have significant imaging-related exposure to radiation. The authors believe it is possible to continue the current improved outcomes in SAH with a significant reduction in radiation exposure from imaging studies. This analysis highlights the significance of accurate assessment of radiation exposure as a quality improvement target.

Use of Transcranial Doppler (TCD) ultrasound in the Neurocritical Care Unit

Transcranial Doppler (TCD) is a portable device that uses a handheld 2-MHz transducer. It is most commonly used in subarachnoid hemorrhage where cerebral blood flow velocities in major intracranial blood vessels are measured to detect vasospasm in the first 2 to 3 weeks. TCD is used to detect vasospasm in traumatic brain injury and post-tumor resection, measurement of cerebral autoregulation and cerebrovascular reactivity, diagnosis of acute arterial occlusions in stroke, screening for patent foramen ovale and monitoring of emboli. It can be used to detect abnormally high intracranial pressure and for confirmation of total cerebral circulatory arrest in brain death.

Early prediction of delayed cerebral ischemia after subarachnoid hemorrhage: development and validation of a practical risk chart

BACKGROUND AND PURPOSE

To develop and validate a risk chart for prediction of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage based on admission characteristics.

METHODS

For derivation of the risk chart, we studied data from 371 prospectively collected consecutive subarachnoid hemorrhage patients with a confirmed aneurysm admitted between 1999 and 2007. For its validation we similarly studied 255 patients admitted between 2007 and 2009. The predictive value of admission characteristics was tested in logistic regression models with delayed cerebral ischemia-related infarction as primary outcome. Procedure-related infarctions were not included. Performance of the models was tested by discrimination and calibration. On the basis of these models, a risk chart was developed for application in clinical practice.

RESULTS

The strongest predictors were clinical condition on admission, amount of blood on computed tomography (both cisternal and intraventricular) and age. A model that combined these 4 predictors had an area under the receiver operating characteristic curve of 0.63 (95% confidence interval, 0.57-0.69). This model improved little by including current smoking and hyperglycemia on admission (area under the receiver operating characteristic curve, 0.65; 95% confidence interval, 0.59-0.71). The risk chart predicted risks of delayed cerebral ischemia-related infarction varying from 12% to 61%. Both low risk (<20% risk) and high risk (>40% risk) were predicted in ≈20% of the patients. Validation confirmed that the discriminative ability was adequate (area under the receiver operating characteristic curve, 0.69; 95% confidence interval, 0.61-0.77).

CONCLUSIONS

Absolute risks of delayed cerebral ischemia-related infarction can be reliably estimated by a simple risk chart that includes clinical condition on admission, amount of blood on computed tomography (both cisternal and intraventricular), and age.