1. Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD, USA;
2. Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD, USA;
3. Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA;
4. Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA;
5. Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA