[1] Univ Klinikum Munster, Klin Neurochirurg, Albert Schweitzer Campus 1,Gebaude A1, D-48149 Munster, Germany
[2] Univ Klinikum Erlangen, Neurol Klin, Schwabachanlage 6, D-91054 Erlangen, Germany
[3] Uniklin Koln, Klin & Poliklin Neurol, Kerpener Str 62, D-50937 Cologne, Germany