1. Department of Neurology, Leiden University Medical Center, Leiden, the Netherlands
2. Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, the Netherlands
3. Department of Neurology, Medisch Spectrum Twente, Enschede, the Netherlands
4. Department of Neurology, Haga Teaching Hospital, The Hague, the Netherlands
5. Department of Neurosurgery, Haga Teaching Hospital, The Hague, the Netherlands
6. Department of Neurosurgery, Leiden University Medical Center, Leiden, the Netherlands