1. Department of Neurology, University of Miami Miller School of Medicine, FL (N.B.S.).
2. Department of Neurology, Massachusetts General Hospital/Harvard Medical School, Boston (M.K.).
3. National Heart Lung and Blood Institute, Bethesda, MD (P.D.-N.).
4. Department of Medicine, University of Toronto, ON, Canada (C.S.).
5. Department of Neurology, Wake Forest University School of Medicine, Winston-Salem, NC (C.B.).