1. University of Groningen, University Medical Center Groningen, Department of Pediatrics, Division of Developmental Neurology, Groningen, The Netherlands;
2. University of Groningen, University Medical Center Groningen, Department of Rehabilitation Medicine, Center for Rehabilitation, Groningen, The Netherlands;
3. Radboud University Medical Center Nijmegen, Department of Neurology, Nijmegen, The Netherlands;
4. University of Groningen, University Medical Center Groningen, Department of Epidemiology, Groningen, The Netherlands;
5. Rehabilitation Center “Revalidatie Friesland”, Beetsterzwaag, The Netherlands;
6. BOSK, Association of persons with a physical disability, Utrecht, The Netherlands