1. Department of Neurosurgery, Thomas Jefferson University School of Medicine, Jefferson Hospital for Neuroscience, Philadelphia, Pennsylvania
2. Department of Neurosurgery, Ewha Womans University School of Medicine, Seoul, Korea
3. Department of Neurosurgery, Penn State University School of Medicine, Hershey, Pennsylvania
4. Department of Health Evaluation Sciences, Pennsylvania State University College of Medicine, Hershey, Pennsylvania