[1] Witten Herdecke Univ, Fac Hlth, Dept Med, D-58448 Witten, Germany
[2] Univ Munster, St Barbara Hosp, Acad Hosp Westfael Wilhelms, Dept Neurosurg, D-59073 Hamm, Germany
[3] Hannover Med Sch, St Marien Hosp, Acad Hosp, Dept Neurosurg, D-49076 Osnabruck, Germany
[4] Univ Hosp Muenster, Dept Neurosurg, D-48149 Munster, Germany
[5] Univ Hosp Muenster, Inst Neuropathol, D-48149 Munster, Germany
[6] Witten Herdecke Univ, Acad Hosp Koeln Merheim, Dept Neurosurg, D-51109 Cologne, Germany