[1] Univ Bonn, Dept Neurol, D-53111 Bonn, Germany
[2] Univ Marburg, Dept Neurol, D-35032 Marburg, Germany
[3] Harvard Univ, Sch Med, MGH Inst Technol Assessment, Boston, MA 02115 USA
[4] Harvard Univ, Sch Med, Dept Radiol, Boston, MA 02115 USA
[5] Univ Mannheim, Dept Neurol, Mannheim, Germany