1. Department of Neurosurgery ML 515, College of Medicine, University of Cincinnati, 231 Bethesda Avenue, Cincinnati, Ohio 45267
2. Department of Neurosurgery, J. N. Gamble Institute of Medical Research, and the Christ Hospital, 2141 Auburn Avenue, Cincinnati, Ohio 45219
3. Mayfield Neurological Institute, 506 Oak Street, Cincinnati, Ohio 45219
4. Department of Anatomy and Cell Biology, College of Medicine, University of Cincinnati, Cincinnati, Ohio 45267
5. Department of Emergency Medicine, College of Medicine, University of Cincinnati, Cincinnati, Ohio 45267
6. Department of Neurosurgery, Veterans American Hospital, 3200 Vine Street, Cincinnati, Ohio 45220