1. University of Tennessee Health Science Center, Memphis, TN 38163, USA
2. University of Tennessee Health Science Center, Memphis, TN, USA
3. John Wesling Medical Center Minden, Ruhr University Bochum, Minden, Germany
4. University Dulsury-Essen, Essen, Germany
5. Semmes-Murphey Neurosurgery, Memphis, TN, USA
6. Banner University Hospital, University of Arizona College of Medicine, Phoenix, AZ
7. National and Kapodistrian University of Athens, Athens, Greece