1. From the Vivian L. Smith Department of Neurosurgery, University of Texas Health Science Center, Houston (S.L.B.)
2. Department of Neurosurgery (A.W.G.), University of Minnesota, Minneapolis
3. Department of Neurology (C.B.S.), Duke University Medical Center, Durham, NC
4. Department of Neurosurgery (E.F.H.), Duke University Medical Center, Durham, NC
5. Department of Radiology (B.J.), University of Minnesota, Minneapolis
6. Department of Neurology and Neuroscience, University of Virginia, Charlottesville (J.J.P.).