1. Department of Neurology, Warren Alpert Medical School, Brown University, Providence, Rhode Island
2. Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, New York
3. Department of Neurology, Tulane University, New Orleans, Louisiana
4. Department of Neurology, Warren Alpert Medical School, Brown University, Providence, Rhode Island 4Department of Diagnostic Imaging, Warren Alpert Medical School, Brown University, Providence, Rhode Island
5. Department of Emergency Medicine, Warren Alpert Medical School, Brown University, Providence, Rhode Island
6. Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, New York6Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York