1. School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
2. School of Medicine, Stanford University, Stanford, CA 94305, USA
3. Department of Cardiothoracic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA
4. Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA
5. Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA
6. Department of Neurology, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA