1. Department of Neurology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
2. Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
3. Department of Radiology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
4. Department of Neurology and Neurosurgery, The University of Texas Health Science Center at Houston, Houston, TX, USA
5. Department of Anesthesia, University of Iowa Hospitals and Clinics, Iowa City, IA, USA