[1] Univ Hosp Essen, Dept Neurosurg & Spine Surg, Essen, Germany
[2] Univ Duisburg Essen, C TNBS, Essen, Germany
[3] St Josephs Hosp, Barrow Neurol Inst, Dept Neurosurg, Phoenix, AZ USA
[4] Univ Hosp Essen, Inst Diagnost & Intervent Radiol & Neuroradiol, Essen, Germany
[5] Univ Hosp Essen, Inst Med Informat Biometry & Epidemiol, Essen, Germany
[6] Univ Hosp Zurich, Dept Neurol, Zurich, Switzerland