1. Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
2. Department of Neurology, University of Toronto School of Medicine, Toronto, Ontario, Canada
3. Department of Epidemiology and Biostatistics, Western University, London, Ontario, Canada
4. Department of Neurology, University of Texas Southwestern School of Medicine, Dallas
5. Department of Neurology, School of Medicine, University of California, San Francisco
6. Stroke Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland