1. From the Department of Neurosurgery (R.M.S., R.J.K., M.L.O., L.E.F., B.Y.H., M.C.G., R.R.S., M.B.S., R.A.S., S.D.L., E.S.C., P.M.M.), Columbia University, New York, NY; the Department of Neurosurgery (D.K.H.), Northwestern University, Chicago, Ill; and the Department of Interventional Neuroradiology (S.D.L., P.M.M.), Columbia University, New York, NY.