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The hyperdense vessel sign on CT predicts successful recanalization with the Merci device in acute ischemic stroke

The success of mechanical clot retrieval for acute ischemic stroke may be influenced by the characteristics of the occlusive thrombus. The thrombus can be partly characterized by CT, as the hyperdense vessel sign (HVS) suggests erythrocyte-rich clot whereas fibrin-rich clot may be isodense. We hypothesized that the physical clot characteristics that determine CT density may also determine likelihood of retrieval with the Merci device.

We reviewed all acute stroke cases initially imaged with non-contrast CT before attempted Merci clot retrieval at a single center between 2004 and 2010. Each CT was blindly assessed for the presence or absence of the HVS, and post-retrieval angiograms were blindly assessed for reperfusion using the TICI scale.

Of 67 patients analyzed (mean age 69; median NIHSS 19; 61% female), the HVS was seen in 42, and no HVS was present in 25. Successful recanalization was achieved in 79% of patients with the HVS (33/42), but in only 36% (9/25) of patients without HVS (p=0.001). The HVS was the only significant predictor of recanalization while accounting for age, treatment with IV-tPA, clot location, stroke etiology, time to treatment, and number of retrieval attempts.

The HVS in acute ischemic stroke was strongly predictive of successful recanalization using the Merci device. The HVS may indicate thrombi that are less adhesive compared with isodense clots that are more resistant to mechanical retrieval. The absence of HVS on pre-treatment CT may thus suggest the need for a more aggressive or alternative therapeutic approach.

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Clinical Significance of Impaired Cerebrovascular Autoregulation After Severe Aneurysmal Subarachnoid Hemorrhage [Original Contributions]

The purpose of this study was to investigate the relationship between cerebrovascular autoregulation and outcome after aneurysmal subarachnoid hemorrhage.

In a prospective observational study, 80 patients after severe subarachnoid hemorrhage were continuously monitored for cerebral perfusion pressure and partial pressure of brain tissue oxygen for an average of 7.9 days (range, 1.9–14.9 days). Autoregulation was assessed using the index of brain tissue oxygen pressure reactivity (ORx), a moving correlation coefficient between cerebral perfusion pressure and partial pressure of brain tissue oxygen. High ORx indicates impaired autoregulation; low ORx signifies intact autoregulation. Outcome was determined at 6 months and dichotomized into favorable (Glasgow Outcome Scale 4–5) and unfavorable outcome (Glasgow Outcome Scale 1–3).

Twenty-four patients had a favorable and 56 an unfavorable outcome. In a univariate analysis, there were significant differences in autoregulation (ORx 0.19±0.10 versus 0.37±0.11, P<0.001, for favorable versus unfavorable outcome, respectively), age (44.1±11.0 years versus 54.2±12.1 years, P=0.001), occurrence of delayed cerebral infarction (8% versus 46%, P<0.001), use of coiling (25% versus 54%, P=0.02), partial pressure of brain tissue oxygen (24.9±6.6 mmüHg versus 21.8±6.3 mmüHg, P=0.048), and Fisher grade (P=0.03). In a multivariate analysis, ORx (P<0.001) and age (P=0.003) retained an independent predictive value for outcome. ORx correlated with Glasgow Outcome Scale (r=–0.70, P<0.001).

The status of cerebrovascular autoregulation might be an important pathophysiological factor in the disease process after subarachnoid hemorrhage, because impaired autoregulation was independently associated with an unfavorable outcome.

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Endovascular Treatment of Intracranial Unruptured Aneurysms: A Systematic Review of the Literature on Safety with Emphasis on Subgroup Analyses [Neuroradiology]

To report subgroup analyses of an updated systematic review on endovascular treatment of intracranial unruptured aneurysms (UAs); to compare types of embolic agents, adjunct techniques, and newer devices; and to identify potential risk factors for poor outcomes.

Meta-Analysis of Observational Studies in Epidemiology and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were used to prepare this article, and the literature was searched with PubMed and with EMBASE and Cochrane databases. Six eligibility criteria (procedural complications rates; at least 10 patients; saccular, nondissecting UAs; original study published in English or French between January 2003 and July 2011; methodological quality score > 6 [modified Strengthening and Reporting of Observational Studies in Epidemiology criteria]; a study published in a peer-reviewed journal) were used. End points included procedural mortality and unfavorable outcomes (death or modified Rankin Scale, Glasgow Outcome Scale, or World Federation of Neurosurgeons Scale at 1 month scores, all > 2). A fixed-effects model (Mantel-Haenszel) was used for pooled estimates of mortality and unfavorable outcomes; a random-effects model (DerSimonian-Laird) was used in case of heterogeneity.

Ninety-seven studies with 7172 patients (26 studies published July 2008 through July 2011) were included. Sixty-nine (1.8%) of 7034 patients died (fixed-effect weighted average; 99% confidence interval [CI]: 1.4%, 2.4%; Q value, 55.0; I² = 0%). Unfavorable outcomes, including death, occurred in 4.7% (242 of 6941) of patients (99% CI: 3.8, 5.7; Q value, 128.3; I² = 26.8%). Patients treated after 2004 had better outcomes (unfavorable outcome, 3.1; 99% CI: 2.4, 4.0) than patients treated during 2001–2003 (unfavorable outcome, 4.7%; 99% CI: 3.6%, 6.1%; P = .01) or in 2000 and before (unfavorable outcome, 5.6%; 99% CI: 4.7%, 6.6%; P < .001). Significantly higher risk was associated with liquid embolic agents (8.1%; 99% CI: 4.7%, 13.7%) versus simple coil placement (4.9%; 99% CI: 3.8%, 6.3%; P = .002). Unfavorable outcomes occurred in 11.5% (99% CI: 4.9%, 24.6%) of patients treated with flow diversion.

Procedure-related poor outcomes occurred (4.7% of patients), risks decreased, and liquid embolic agents and flow diversion were associated with higher risks.

©RSNA, 2012

Supplemental material:http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112114/-/DC1

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Closed-Cell Stent for Coil Embolization of Intracranial Aneurysms: Clinical and Angiographic Results [INTERVENTIONAL]

Recanalization is observed in 20–40% of endovascularly treated intracranial aneurysms. To further reduce the recanalization and expand endovascular treatment, we evaluated the safety and efficacy of closed-cell SACE.

Between 2007 and 2010, 147 consecutive patients (110 women; mean age, 54 years) presenting at 2 centers with 161 wide-neck ruptured and unruptured aneurysms were treated by using SACE. Inclusion criteria were wide-neck aneurysms (>4 mm or a dome/neck ratio ≤2). Clinical outcomes were assessed by the mRS score at baseline, discharge, and follow-up. Aneurysm occlusion was assessed on angiograms by using the RS immediately after SACE and at follow-up.

Eighteen aneurysms (11%) were treated following rupture. Procedure-related mortality and permanent neurologic deficits occurred in 2 (1.4%) and 5 patients (3.4%), respectively. In total, 7 patients (4.8%) died, including 2 with reruptures. Of the 140 surviving patients, 113 (80.7%) patients with 120 aneurysms were available for follow-up neurologic examination at a mean of 11.8 months. An increase in mRS score from admission to follow-up by 1, 2, or 3 points was seen in 7 (6.9%), 1 (1%), and 2 (2%) patients, respectively. Follow-up angiography was performed in 120 aneurysms at a mean of 11.9 months. Recanalization occurred in 12 aneurysms (10%), requiring retreatment in 7 (5.8%). Moderate in-stent stenosis was seen in 1 (0.8%), which remained asymptomatic.

This series adds to the evidence demonstrating the safety and effectiveness of SACE in the treatment of intracranial aneurysms. However, SACE of ruptured aneurysms and premature termination of antiplatelet treatment are associated with increased morbidity and mortality.

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Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association [AHA/ASA Guideline]

The aim of this guideline is to present current and comprehensive recommendations for the diagnosis and treatment of aneurysmal subarachnoid hemorrhage (aSAH).

A formal literature search of MEDLINE (November 1, 2006, through May 1, 2010) was performed. Data were synthesized with the use of evidence tables. Writing group members met by teleconference to discuss data-derived recommendations. The American Heart Association Stroke Council's Levels of Evidence grading algorithm was used to grade each recommendation. The guideline draft was reviewed by 7 expert peer reviewers and by the members of the Stroke Council Leadership and Manuscript Oversight Committees. It is intended that this guideline be fully updated every 3 years.

Evidence-based guidelines are presented for the care of patients presenting with aSAH. The focus of the guideline was subdivided into incidence, risk factors, prevention, natural history and outcome, diagnosis, prevention of rebleeding, surgical and endovascular repair of ruptured aneurysms, systems of care, anesthetic management during repair, management of vasospasm and delayed cerebral ischemia, management of hydrocephalus, management of seizures, and management of medical complications.

aSAH is a serious medical condition in which outcome can be dramatically impacted by early, aggressive, expert care. The guidelines offer a framework for goal-directed treatment of the patient with aSAH.

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Single-Center Experience of Cerebral Artery Thrombectomy Using the TREVO Device in 60 Patients With Acute Ischemic Stroke [Original Contributions; Brief Reports]

We sought to explore the safety and efficacy of the new TREVO stent-like retriever in consecutive patients with acute stroke.

We conducted a prospective, single-center study of 60 patients (mean age, 71.3 years; male 47%) with stroke lasting <8 hours in the anterior circulation (n=54) or <12 hours in the vertebrobasilar circulation (n=6) treated if CT perfusion/CT angiography confirmed a large artery occlusion, ruled out a malignant profile, or showed target mismatch if symptoms >4.5 hours. Successful recanalization (Thrombolysis In Cerebral Infarction 2b–3), good outcome (modified Rankin Scale score 0–2) and mortality at Day 90, device-related complications, and symptomatic hemorrhage (parenchymal hematoma Type 1 or parenchymal hematoma Type 2 and National Institutes of Health Stroke Scale score increment ≥4 points) were prospectively assessed.

Median (interquartile range) National Institutes of Health Stroke Scale score on admission was 18 (12–22). The median (interquartile range) time from stroke onset to groin puncture was 210 (173–296) minutes. Successful revascularization was obtained in 44 (73.3%) of the cases when only the TREVO device was used and in 52 (86.7%) when other devices or additional intra-arterial tissue-type plasminogen activator were also required. The median time (interquartile range) of the procedure was 80 (45–114) minutes. Good outcome was achieved in 27 (45%) of the patients and the mortality rate was 28.3%. Seven patients (11.7%) presented a symptomatic intracranial hemorrhage. No other major complications were detected.

The TREVO device was reasonably safe and effective in patients with severe stroke. These results support further investigation of the TREVO device in multicentric registries and randomized clinical trials.

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Eligibility for Intravenous Recombinant Tissue-Type Plasminogen Activator Within a Population: The Effect of the European Cooperative Acute Stroke Study (ECASS) III Trial [Original Contributions; Clinical Sciences]

The publication of the European Cooperative Acute Stroke Study (ECASS III) expanded the treatment time to thrombolysis for acute ischemic stroke from 3 to 4.5 hours from symptom onset. The impact of the expanded time window on treatment rates has not been comprehensively evaluated in a population-based study.

All patients with an ischemic stroke presenting to an emergency department during calendar year 2005 in the 17 hospitals that compromise the large 1.3 million Greater Cincinnati/Northern Kentucky population were included in the analysis. Criteria for exclusion from thrombolytic therapy are analyzed retrospectively for both the standard and expanded timeframes with varying door-to-needle times.

During the study period, 1838 ischemic strokes presenting to an emergency department were identified. A small proportion of them arrived in the expanded time window (3.4%) compared with the standard time window (22%). Only 0.5% of those who arrived in this timeframe met eligibility criteria for thrombolysis compared with 5.9% using standard eligibility criteria in the standard timeframe. These results did not vary significantly by repeated analysis varying the door-to-needle time or the expanded time window's exclusion criteria.

In reality, the expanded time window for thrombolysis in acute ischemic stroke benefits few patients. If we are to improve recombinant tissue-type plasminogen activator administration rates, our focus should be on improving stroke awareness, transport to facilities with ability to administer thrombolysis, and familiarity of physicians with acute stroke treatment guidelines.

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Long-Term Clinical and Imaging Follow-Up of Complex Intracranial Aneurysms Treated by Endovascular Parent Vessel Occlusion