1. Department of Neurology Beatrix Children's Hospital University Medical Center Groningen University of Groningen Groningen the Netherlands
2. Department of General Medicine University Medical Center Groningen University of Groningen Groningen the Netherlands
3. Department of Epidemiology University Medical Center Groningen University of Groningen Groningen the Netherlands
4. Department of Pediatrics Beatrix Children's Hospital University Medical Center Groningen University of Groningen Groningen the Netherlands