1. From the Departments of Neurology (C.D.S.), Radiology (P.W.S.), and Pathology (D.H.O.), Massachusetts General Hospital, and the Departments of Neurology (C.D.S.), Radiology (P.W.S.), and Pathology (D.H.O.), Harvard Medical School — both in Boston; and the Department of Neurology, National Prion Disease Pathology Surveillance Center, Case Western Reserve University School of Medicine, Cleveland (B.S.A.).