1. From the Departments of Radiology (P.M.M.), Neurological Surgery (P.M.M., E.S.C.), Anesthesiology (E.J.H.), Neurology (E.J.H.), and Cardiology (W.A.G.), Columbia University, College of Physicians and Surgeons, New York, NY; Department of Medicine, LeHigh Valley Hospital and Health Network, Allentown, PA (H.C.S.); and Departments of Radiology, Neurology, Neurological Surgery, and Critical Care, University of California San Francisco (R.T.H.).