Poor Correlation Between Perihematomal MRI Hyperintensity and Brain Swelling After Intracerebral Hemorrhage

The perihematomal hyperintensity is commonly interpreted to represent cerebral edema following ICH, but the accuracy of this interpretation is unknown. We therefore investigated the relationship between changes in PHH and changes in hemispheric brain volume as a measure of edema during the first week after ICH

Autoregulation after ischaemic stroke

Absent outcome data from randomized clinical trials, management of hypertension in acute ischaemic stroke remains controversial. Data from human participants have failed to resolve the question whether cerebral blood flow (CBF) in the peri-infarct region will decrease due to impaired autoregulation when systemic mean arterial pressure (MAP) is rapidly reduced

Cerebellum as the Normal Reference for the Detection of Increased Cerebral Oxygen Extraction

Hemispheric ratios of oxygen extraction fraction (OEF), a proven methodology for the detection of severe hemodynamic impairment and stroke risk, are not sensitive for detecting bilateral hemispheric increases in OEF. The aim of this study was to investigate the use of cerebellum as the reference normal. We analyzed positron emission tomographic (PET) measurements of count-based OEF and clinical data from 57 patients with unilateral atherosclerotic carotid occlusion and 13 controls enrolled in a prospective study of stroke risk. The ipsilateral, contralateral, and total cerebellum were each evaluated as possible reference regions, and the ratios of the middle cerebral artery (MCA) hemispheric OEF counts against those in each reference region were determined. A statistically significant correlation (P<0.0001) was observed with all three MCA-to-cerebellar ratios when compared with the gold standard of ipsilateral-to-contralateral MCA hemispheric ratio. Kaplan–Meier analyses showed all MCA-to-cerebellar ratios to be predictive of stroke. By using the total cerebellum method, 7 strokes were found to have occurred in 20 patients with increased OEF (P=0.0007), compared with 7 strokes out of 16 patients with elevated OEF using the ipsilateral or contralateral cerebellum methods (P<0.0001). These methods may be useful for categorizing the hemodynamic status of patients with bilateral cerebral occlusive diseases, including atherosclerosis and moyamoya, to determine the association with the risk of subsequent stroke

Cerebral Mitochondrial Metabolism in Early Parkinson's Disease

Abnormal cerebral energy metabolism due to dysfunction of mitochondrial electron transport has been implicated in the pathogenesis of Parkinson Disease (PD). However, in vivo data of mitochondrial dysfunction has been inconsistent. We directly investigated mitochondrial oxidative metabolism in vivo in 12 patients with early, never-medicated PD and 12 age-matched normal controls by combined measurements of the cerebral metabolic rate of oxygen (CMRO2) and the cerebral metabolic rate of glucose (CMRglc) with positron emission tomography. The primary analysis showed a statistically significant 24% increase in bihemispheric CMRO2 and no change in CMRO2/CMRglc. These findings are inconsistent with a defect in mitochondrial oxidative phosphorylation due to reduced activity of the mitochondrial ETS. Since PD symptoms were already manifest, deficient energy production due to a reduced activity of the mitochondrial ETS cannot be a primary mechanism of neuronal death in early PD. Alternatively, this general increase in CMRO2 could be due, not to increased metabolic demand, but to an uncoupling of ATP production from oxidation in the terminal stage of oxidative phosphorylation. Whether this is the case in early PD and whether or not it is important in the pathogenesis of PD will require further study

Surgical results of the carotid occlusion surgery study: Clinical article

The Carotid Occlusion Surgery Study (COSS) was conducted to determine if STA-MCA bypass, when added to best medical therapy, would reduce subsequent ipsilateral stroke in patients with complete ICA occlusion and an elevated OEF in the cerebral hemisphere distal to the carotid occlusion. A recent publication reported the methodology of COSS in detail and briefly outlined the major findings of the trial.29 The surgical results of COSS are described in detail in this report

Lower stroke risk with lower blood pressure in hemodynamic cerebral ischemia

OBJECTIVE: To determine whether strict blood pressure (BP) control is the best medical management for patients with symptomatic carotid artery occlusion and hemodynamic cerebral ischemia. METHODS: In this prospective observational cohort study, we analyzed data from 91 participants in the nonsurgical group of the Carotid Occlusion Surgery Study (COSS) who had recent symptomatic internal carotid artery occlusion and hemodynamic cerebral ischemia manifested by ipsilateral increased oxygen extraction fraction. The target BP goal in COSS was ≤130/85 mm Hg. We compared the occurrence of ipsilateral ischemic stroke during follow-up in the 41 participants with mean BP ≤130/85 mm Hg to the remaining 50 with higher BP. RESULTS: Of 16 total ipsilateral ischemic strokes that occurred during follow-up, 3 occurred in the 41 participants with mean follow-up BP of ≤130/85 mm Hg, compared to 13 in the remaining 50 participants with mean follow-up BP >130/85 mm Hg (hazard ratio 3.742, 95% confidence interval 1.065-13.152, log-rank p = 0.027). CONCLUSION: BPs ≤130/85 mm Hg were associated with lower subsequent stroke risk in these patients. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that control of hypertension ≤130/85 mm Hg is associated with a reduced risk of subsequent ipsilateral ischemic stroke in patients with recently symptomatic carotid occlusion and hemodynamic cerebral ischemia (increased oxygen extraction fraction)

Extracranial-Intracranial Bypass Surgery for Stroke Prevention in Hemodynamic Cerebral Ischemia: The Carotid Occlusion Surgery Study Randomized Trial

Patients with symptomatic atherosclerotic internal carotid artery occlusion (AICAO) and hemodynamic cerebral ischemia are at high risk for subsequent stroke when treated medically

Dynamic susceptibility contrast MRI with localized arterial input functions

Compared to gold-standard measurements of cerebral perfusion with positron emission tomography (PET) using H2[15O] tracers, measurements with dynamic susceptibility contrast (DSC) MR are more accessible, less expensive and less invasive. However, existing methods for analyzing and interpreting data from DSC MR have characteristic disadvantages that include sensitivity to incorrectly modeled delay and dispersion in a single, global arterial input function (AIF). We describe a model of tissue microcirculation derived from tracer kinetics which estimates for each voxel a unique, localized AIF (LAIF). Parameters of the model were estimated using Bayesian probability theory and Markov-chain Monte Carlo, circumventing difficulties arising from numerical deconvolution. Applying the new method to imaging studies from a cohort of fourteen patients with chronic, atherosclerotic, occlusive disease showed strong correlations between perfusion measured by DSC MR with LAIF and perfusion measured by quantitative PET with H2[15O]. Regression to PET measurements enabled conversion of DSC MR to a physiological scale. Regression analysis for LAIF gave estimates of a scaling factor for quantitation which described perfusion accurately in patients with substantial variability in hemodynamic impairment