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