1. Department of Neurology , Aristotle University of Thessaloniki, George Papanikolaou Hospital, Thessaloniki, 570 10 Greece,
2. Department of Haematology, Bone Marrow Transplantation Unit, George Papanikolaou Hospital, Thessaloniki, 570 10 Greece
3. Department of Neurology , Aristotle University of Thessaloniki, George Papanikolaou Hospital, Thessaloniki, 570 10 Greece