1 From the Departments of Anesthesiology and Critical Care Medicine (R.D.S., Y.H.), Neurology (R.D.S., Y.H.), Neurosurgery (R.D.S.), and Radiology (R.D.S.), Johns Hopkins University School of Medicine, Baltimore, MD. rstevens@jhmi.edu.
2 From the Departments of Anesthesiology and Critical Care Medicine (R.D.S., Y.H.), Neurology (R.D.S., Y.H.), Neurosurgery (R.D.S.), and Radiology (R.D.S.), Johns Hopkins University School of Medicine, Baltimore, MD.