1. Resident Neurosurgeon, Department of Neurosurgery, Academic Hospital Groningen, Groningen, The Netherlands.
2. Staff Anesthesiologist, Department of Anesthesiology, Onze Lieve Vrouwe Gasthuis, Amsterdam, The Netherlands.
3. Staff Neurosurgeon, Department of Neurosurgery.
4. Research Associate, Department of Clinical Epidemiology and Biostatistics, Academic Medical Center, University of Amsterdam.
5. Staff Anesthesiologist, Department of Anesthesiology, St. Antonius Hospital, Nieuwegein, The Netherlands.
6. Professor of Anesthesiology, Department of Anesthesiology, University Hospital Utrecht, The Netherlands.