1. Department of Neurosurgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
2. Department of Neurosurgery, Friedrich-Ebert Krankenhaus, Neumünster, Germany
3. Division of Spine Surgery, Department of Trauma and Orthopedic Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
4. Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany