1. Department of Neurology, Virginia Tech Carilion Clinic School of Medicine, Roanoke, Virginia, USA;
2. Section of Neurosurgery, Carilion Clinic, Roanoke, Virginia, USA;
3. Neurointerventional Surgery, Department of Radiology, Carilion Clinic, Roanoke, Virginia, USA;
4. Virginia Tech Carilion School of Medicine, Roanoke, Virginia, USA