1. Department of Neurosurgery, Carilion Clinic, 1906 Belleview Avenue, Roanoke, VA 24014, USA
2. Virginia Tech Carilion School of Medicine, 2 Riverside Circle, Roanoke, VA 24016, USA
3. School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
4. Carilion Clinic Radiology, Roanoke, VA 24016, USA