1. Department of Neurology, Leiden University Medical Centre, Leiden
2. Department of Paediatrics, Leiden University Medical Centre, Leiden
3. Department of Neurology, Erasmus Medical Centre Rotterdam, Rotterdam
4. Department of Paediatric Neurology, Erasmus Medical Centre Rotterdam and Sophia Children's Hospital, Rotterdam
5. Department of Paediatric Neurology, University Medical Centre Utrecht, and Wilhelmina Children's Hospital, Utrecht
6. Department of Paediatric Neurology, St. Elisabeth Hospital, Tilburg
7. Department of Neurology, University Hospital Groningen, Groningen, the Netherlands