[1] Tech Univ Munich, Sch Med, Dept Neurosurg, Ismaningerstr 22, D-81675 Munich, Germany
[2] Charite Univ med Berlin, Dept Neurosurg, Augustenburger Pl 1, D-13353 Berlin, Germany
[3] Free Univ Berlin, Augustenburger Pl 1, D-13353 Berlin, Germany
[4] Humboldt Univ, Augustenburger Pl 1, D-13353 Berlin, Germany
[5] Berlin Inst Hlth, Augustenburger Pl 1, D-13353 Berlin, Germany
[6] Med Univ Innsbruck, Dept Neurosurg, Anichstr 35, A-6020 Innsbruck, Austria
[7] Univ Med Ctr Hamburg Eppendorf, Dept Neurosurg, Martinistr 52, D-20251 Hamburg, Germany
[8] Univ Hosp Frankfurt, Dept Neurosurg, Theodor Stern Kai 7, D-60590 Frankfurt, Germany
[9] Univ Freiburg, Med Ctr, Dept Neurosurg, Breisacher Str 64, D-79106 Freiburg, Germany
[10] Georg August Univ Gottingen, Dept Neurosurg, Robert Koch Str 40, D-37075 Gottingen, Germany
[11] Johannes Gutenberg Univ Mainz, Univ Med Ctr, Dept Neurosurg, Langenbeckstr 1, D-55131 Mainz, Germany
[12] Univ Geneva, Geneva Univ Med Ctr, Dept Neurosurg, Rue Gabrielle Perret Gentil 4, CH-1205 Geneva, Switzerland
[13] Univ Geneva, Fac Med, Rue Gabrielle Perret Gentil 4, CH-1205 Geneva, Switzerland