1. Department of Neurosurgery, Leiden University Medical Center , Leiden , The Netherlands
2. Department of Neurology, Leiden University Medical Center , Leiden , the Netherlands
3. Department of Neurology, Haaglanden Medical Center , the Hague , the Netherlands
4. Department of Radiology, Leiden University Medical Center , Leiden , the Netherlands
5. Department of Neurosurgery, Erasmus University Medical Center , Rotterdam , the Netherlands
6. Department of Neurosurgery, Haaglanden Medical Center , the Hague , the Netherlands
7. Department of Neurosurgery, Haga Teaching Hospital , the Hague , the Netherlands