1 Department of Neurosurgery at Banner, University Medical Center, 755 East McDowell Road, 2nd Floor, Phoenix, AZ 85006, USA. Electronic address: peter.nakaji@bannerhealth.com.
2 Department of Neurosurgery at Kantonsspital St. Gallen, Klinik für Neurochirurgie, St. Gallen CH-9000, Switzerland. Electronic address: oliver.bozinov@kssg.ch.