1. Division of Neurosurgery, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
2. Department of Neurosurgery, George Washington University Medical Center, Washington, District of Columbia
3. Department of Neurosurgery, Mt. Sinai Medical Center, New York, New York
4. Department of Neurosurgery, Kifisia District Hospital, Kifisia-Athens, Greece
5. Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
6. Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania