[1] Hosp German Armed Forces, Dept Neurosurg, Lange Str 38, D-26655 Westerstede, Germany
[2] Hannover Med Sch, Dept Hematol Hemostasis Oncol & Stem Cell Transpla, Hannover, Germany
[3] Hannover Med Sch, Dept Traumatol & Orthoped Surg, Hannover, Germany
[4] Hannover Med Sch, Dept Neuropathol, Hannover, Germany
[5] Helmut Schmidt Univ, Univ German Armed Forces, Dept Mech Engn, Lab Mfg Technol, Hamburg, Germany