1. Department of Neurological Surgery, Virginia Commonwealth University Medical Center, Richmond, Virginia
2. Department of Neurological Surgery, University of Washington School of Medicine, Harborview Medical Center, Seattle, Washington
3. Department of Neurological Surgery, Weil Cornell Medical College of Cornell University, New York, New York
4. Department of Neurological Surgery, Montefiore Medical Center, Bronx, New York
5. Department of Neurological Surgery, Swedish Medical Center, Seattle, Washington
6. Department of Neurological Surgery, M. Bufalini Hospital, Cesena, Italy
7. Department of Neurological Surgery, New York University School of Medicine, New York, New York
8. Department of Neurological Surgery, Allegheny General Hospital, Pittsburgh, Pennsylvania