Background and Purpose-Although data on some risk factors for intracerebral hemorrhage (ICH) already are beyond doubt, for other factors, the evidence is less clear. We performed a systematic overview of case-control and cohort studies on risk factors for ICH. Methods-We searched MEDLINE, LILACS, EXTRAMED, and Pascal from 1966 to 2001 to identify studies. Studies were included if they met predefined methodological criteria. When possible, 2ϫ2 tables were extracted and combined with the Mantel-Haenszel method. Summary odds ratios (ORs) were calculated for case-control studies, and summary relative risks (RRs) were found for cohort studies and for case-control and cohort studies combined. Results-Fourteen case-control and 11 cohort studies were identified. We could not always combine the results of case-control and cohort studies. In cohort studies, the crude RR for age (every 10-year increase) was 1.97 (95% confidence interval [CI], 1.79 to 2.16). In case-control studies, the crude OR for high alcohol intake was 3.36 (95% CI, 2.21 to 5.12) and for hypertension was 3.68 (95% CI, 2.52 to 5.38). Two cohort studies showed an increasing risk of ICH with increasing degree of hypertension. In cohort and case-control studies combined, the crude RR for sex (male versus female) was 3.73 (95% CI, 3.28 to 4.25); for current smoking, 1.31 (95% CI, 1.09 to 1.58); and for diabetes, 1.30 (95% CI, 1.02 to 1.67). Conclusions-Risk factors for ICH appeared to be age, male sex, hypertension, and high alcohol intake. High cholesterol tends to be associated with a lower risk of ICH. We could not assess whether these risk factors are independent. (Stroke.

Here we report the first quantitative analysis of spiking activity in human early visual cortex. We recorded multi-unit activity from two electrodes in area V2/V3 of a human patient implanted with depth electrodes as part of her treatment for epilepsy. We observed well-localized multi-unit receptive fields with tunings for contrast, orientation, spatial frequency, and size, similar to those reported in the macaque. We also observed pronounced gamma oscillations in the local-field potential that could be used to estimate the underlying spiking response properties. Spiking responses were modulated by visual context and attention. We observed orientation-tuned surround suppression: responses were suppressed by image regions with a uniform orientation and enhanced by orientation contrast. Additionally, responses were enhanced on regions that perceptually segregated from the background, indicating that neurons in the human visual cortex are sensitive to figure-ground structure. Spiking responses were also modulated by object-based attention. When the patient mentally traced a curve through the neurons’ receptive fields, the accompanying shift of attention enhanced neuronal activity. These results demonstrate that the tuning properties of cells in the human early visual cortex are similar to those in the macaque and that responses can be modulated by both contextual factors and behavioral relevance. Our results, therefore, imply that the macaque visual system is an excellent model for the human visual cortex.

Background and Purpose-Infarct volume is increasingly used as an outcome measure in clinical trials of therapies for acute ischemic stroke. We tested which of 5 different methods to measure infarct size or volume on CT scans has the highest reproducibility. Methods-Infarct volume and total intracranial volume were measured with Leica Q500 MCP image analysis software, or with a caliper, on 38 CT scans of patients who participated in the Tirilazad Efficacy Stroke Study II (TESS II). The scans were performed 8 days (Ϯ2 days) after the onset of symptoms. The 5 methods tested were based on (1) semiautomated pixel thresholding, (2) manual tracing of the perimeter, (3) a stereological counting grid, (4) measurement of the 3 largest diameters, and (5) the single largest diameter. The measurements were performed independently by 2 observers; the first observer performed all measurements twice. Results-The single largest diameter did not correlate well with infarct volume. Of the other methods, manual tracing of the perimeter of the infarct had the lowest intraobserver and interobserver variability: coefficients of variation were 8.6% and 14.1%, respectively. For total intracranial volume, manual tracing also provided the highest reproducibility: intraobserver and interobserver coefficients of variation were 3.3% and 4.9%, respectively. Conclusions-Manual tracing of the perimeter is the most reproducible method for measuring the volumes of the infarct and the total intracranial space in multicenter trials of therapies for acute ischemic stroke. Key Words: cerebral infarction Ⅲ computer-assisted image processing Ⅲ stroke assessment Ⅲ tomography, x-ray computed I nfarct volume as measured by CT or MRI is increasingly used as a surrogate or auxiliary outcome measure in clinical trials of therapies for acute ischemic stroke. 1-5 Several methods to measure infarct volume on CT scans have been developed, of which manual tracing of the infarct perimeter 6 is the most well established. Other methods are based on pixel thresholding, 7,8 a stereological counting grid, 9 or measurement of the 3 largest diameters. 10 The single largest visible diameter has also been used as a measure for infarct size. 11 If a method for measuring infarct volume is applied in (multicenter) trials, it should be characterized by good reproducibility, even when performed on hard copies of scans of different quality, calibration, and density scale parameters. Although fair interrater reliabilities for some of the techniques have been reported before, 9,10 the present study is the first to compare the reproducibility of the 5 different methods.The aim of the present study was to determine which of the aforementioned methods to measure infarct volume has the highest reproducibility. To express infarct volume as a percentage of the total intracranial volume (ICV), we also compared the intraobserver and interobserver variability of this measure obtained with each of the different methods. Subjects and MethodsMeasurements were performed by 2 of the authors (H....

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