1. Department of Neurology, Leiden University Medical Centre, Leiden, the Netherlands
2. Department of Neurology, University Medical Centre Amsterdam, University of Amsterdam, Amsterdam, the Netherlands
3. Department of Neurology, Isala hospital, Zwolle, the Netherlands
4. Department of Medical Statistics, Leiden University Medical Centre, Leiden, the Netherlands
5. Department of Neurology, Onze Lieve Vrouwe Gasthuis, Amsterdam, the Netherlands
6. Zaans Medical Centre, Zaandam, the Netherlands