1. Department of Orthopedics; Mayo Clinic; Rochester Minnesota
2. Department of Neurosurgery, School of Medicine and Biomedical Sciences, University of Buffalo; State University of New York; Buffalo New York
3. Department of Neurosurgery, Faculty of Medicine; the University of Tokyo; Tokyo Japan
4. Department of Radiology; Mayo Clinic; Rochester Minnesota
5. Department of Neurologic Surgery; Mayo Clinic; Rochester Minnesota
6. Department of Anatomy; Mayo Clinic; Rochester Minnesota