1. Departments of Neurosurgery and Radiology, Illinois Neurological Institute, University of Illinois College of Medicine at Peoria, Peoria, Illinois
2. Department of Neurosurgery, Illinois Neurological Institute, University of Illinois College of Medicine at Peoria, Peoria, Illinois
3. Department of Neurosurgery, University of Florence, Florence, Italy
4. Department of Neurosurgery, Iowa University, Iowa City, Iowa