1. Department of Anesthesia, Stanford University School of Medicine, Stanford, California, U.S.A.
2. Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, U.S.A.
3. Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, U.S.A.
4. Stanford Stroke Center, Stanford University School of Medicine, Stanford, California, U.S.A.