1. Division of Neurosurgery, Evanston Hospital, Evanston, and Northwestern University Medical School, Chicago, Illinois
2. Division of Neurology, Evanston Hospital, Evanston, and Northwestern University Medical School, Chicago, Illinois
3. Department of Community Health, Evanston Hospital, Evanston, and Northwestern University Medical School, Chicago, Illinois
4. Department of Radiology, Evanston Hospital, Evanston, and Northwestern University Medical School, Chicago, Illinois