1. Department of Emergency Medicine; University of Michigan; Ann Arbor; Michigan; U.S.A
2. Department of Neurology; University of California San Francisco; San Francisco; California; U.S.A
3. Department of Public Health Sciences; College of Medicine; Medical University of South Carolina; Charleston; South Carolina; U.S.A
4. National Institute of Neurological Disorders and Stroke; National Institutes of Health; Bethesda; Maryland; U.S.A