Cerebrovascular reserve and stroke risk in patients with carotid stenosis or occlusion: a systematic review and meta-analysis.

BACKGROUND AND PURPOSE: Impairments in cerebrovascular reserve (CVR) have been variably associated with increased risk of ischemic events and may stratify stroke risk in patients with high-grade internal carotid artery stenosis or occlusion. The purpose of this study is to perform a systematic review and meta-analysis to summarize the association of CVR impairment and stroke risk. METHODS: We performed a literature search evaluating the association of impairments in CVR with future stroke or transient ischemic attack in patients with high-grade internal carotid artery stenosis or occlusion. We included studies with a minimum of 1-year patient follow-up with baseline CVR measures performed by any modality and primary outcome measures of stroke and/or transient ischemic attack. A meta-analysis with assessment of study heterogeneity and publication bias was performed. Results were presented in a forest plot and summarized using a random-effects model. RESULTS: Thirteen studies met the inclusion criteria, representing a total of 1061 independent CVR tests in 991 unique patients with a mean follow-up of 32.7 months. We found a significant positive relationship between impairment of CVR and development of stroke with a pooled random effects OR of 3.86 (95% CI, 1.99-7.48). Subset analysis showed that this association between CVR impairment and future risk of stroke/transient ischemic attack remained significant regardless of ischemic outcome measure, symptomatic or asymptomatic disease, stenosis or occlusion, or CVR testing method. CONCLUSIONS: CVR impairment is strongly associated with increased risk of ischemic events in carotid stenosis or occlusion and may be useful for stroke risk stratification.

National initiatives for measuring quality performance for the practicing neuroradiologist.

This article provides an overview of the national initiatives developed for monitoring and reporting quality performance measures. Included is a review of the Physician Quality Reporting System, the Hospital Outpatient Quality Data Reporting Program, and the Hospital Outpatient Prospective Payment System, with specific emphasis on how these programs affect radiology practice. A practical review of these programs allows radiologists to gain further understanding of the economic and political influences on the daily practice of radiology today. The background and relevant features of each program are presented in this article.

Outcomes-based assessment of a new reference standard for delayed cerebral ischemia related to vasospasm in aneurysmal subarachnoid hemorrhage.

RATIONALE AND OBJECTIVES: The purpose is to perform outcomes-based assessment of a new reference standard for delayed cerebral ischemia (DCI) related to vasospasm. MATERIALS AND METHODS: Retrospective study was performed with consecutive aneurysmal subarachnoid hemorrhage (A-SAH) patients between January 2002 and May 2009. A new reference standard for DCI was applied to the study population incorporating clinical and imaging criteria. Diagnostic accuracy was determined by chart diagnosis. Outcome measures for assessment included: permanent neurologic deficits, infarction, functional disability, treatment, and discharge status. Medical record review was performed by two blinded observers. Chi-square test calculated statistical significance between DCI and no DCI groups. RESULTS: A total of 137 patients were included; 59% (81/137) classified as DCI and 41% (56/137) as no DCI by the reference standard. Overall accuracy is 96% (95% confidence interval 92-99) with 100% sensitivity, 92% specificity, 94% positive and 100% negative predictive values. Patients classified as DCI had 40% (32/81) permanent neurologic deficits and 57% (46/81) infarction compared to 0% (0/56) classified as no DCI. DCI patients had 33% (27/81) functional disability compared to 13% (7/56) classified as no DCI. Ninety-four percent (76/81) DCI patients received treatment compared to 0% (0/56) classified as no DCI. DCI group had 46% (37/81) discharged to rehabilitation facilities and 11% (9/81) mortality compared to 25% (14/56) and 2% (1/56), respectively, in no DCI group. There are statistically significant differences (P < .0001) between DCI and no DCI groups for all outcome measures. CONCLUSION: This new reference standard has high diagnostic accuracy for DCI related to vasospasm. The outcomes-based assessment further supports its accuracy in correctly classifying A-SAH patients.

Systemic treatment with liver X receptor agonists raises apolipoprotein E, cholesterol, and amyloid-ß peptides in the cerebral spinal fluid of rats.

BACKGROUND: Apolipoprotein E (apoE) is a major cholesterol transport protein found in association with brain amyloid from Alzheimer's disease (AD) patients and the ε4 allele of apoE is a genetic risk factor for AD. Previous studies have shown that apoE forms a stable complex with amyloid ß (Aß) peptides in vitro and that the state of apoE lipidation influences the fate of brain Aß, i.e., lipid poor apoE promotes Aß aggregation/deposition while fully lipidated apoE favors Aß degradation/clearance. In the brain, apoE levels and apoE lipidation are regulated by the liver X receptors (LXRs). RESULTS: We investigated the hypothesis that increased apoE levels and lipidation induced by LXR agonists facilitates Aß efflux from the brain to the cerebral spinal fluid (CSF). We also examined if the brain expression of major apoE receptors potentially involved in apoE-mediated Aß clearance was altered by LXR agonists. ApoE, cholesterol, Aß40, and Aß42 levels were all significantly elevated in the CSF of rats after only 3 days of treatment with LXR agonists. A significant reduction in soluble brain Aß40 levels was also detected after 6 days of LXR agonist treatment. CONCLUSIONS: Our novel findings suggest that central Aß lowering caused by LXR agonists appears to involve an apoE/cholesterol-mediated transport of Aß to the CSF and that differences between the apoE isoforms in mediating this clearance pathway may explain why individuals carrying one or two copies of APOE ε4 have increased risk for AD.