1. Department of Neurology; Brigham and Women's Hospital; Harvard Medical School; Boston Massachusetts U.S.A
2. Department of Neurology; Massachusetts General Hospital; Harvard Medical School; Boston Massachusetts U.S.A
3. Department of Neurology; Beth Israel Deaconess Medical Center; Harvard Medical School; Boston Massachusetts U.S.A
4. Neurology Service, Internal Medicine department; Hôpital du Valais; 19501 Sion Switzerland
5. Emergency Department; Brigham and Women's Hospital; Harvard Medical School; Boston Massachusetts U.S.A
6. Department of Clinical Neurosciences; CHUV and Lausanne University; Lausanne Switzerland