1. Department of Public Health, Erasmus University Medical Center, Rotterdam, The Netherlands.
2. Department of Neurology, Erasmus University Medical Center, Rotterdam, The Netherlands.
3. Department of Neurosurgery, Antwerp University Hospital and University of Antwerp, Edegem, Belgium.
4. Division of Anaesthesia, University of Cambridge/Addenbrooke's Hospital, Cambridge, United Kingdom.
5. Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands.