1. From the Department of Neurosurgery (J.S.H., M.Z., D.N., D.H.), University of Iowa Hospitals and Clinics, Iowa City
2. Department of Neurosurgery, University of Pennsylvania, Philadelphia (D.K.K.)
3. Department of Neurosurgery, Thomas Jefferson University Hospital, Philadelphia, PA (P.J.).
4. Departments of Neurology, Neurosurgery, and Radiology (E.A.S.), University of Iowa Hospitals and Clinics, Iowa City