1. ; Department of Paediatric Neurology; Leiden University Medical Centre; Leiden The Netherlands
2. ; Department of Neurology; Leiden University Medical Centre; PO Box 9600, K5-Q, 110 Leiden 2300 RC The Netherlands
3. ; Department of Paediatrics; Leiden University Medical Centre; Leiden The Netherlands
4. ; Columbia - Presbyterian Medical Center; The Neurological Institute; New York NY USA
5. ; Department of Neurology; Gröningen University Hospital; Groningen
6. ; Academic Medical Centre; Emma Children's Hospital AMC; Amsterdam The Netherlands