1 Department of Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, United Kingdom; Complex Motor Disorders Service, Evelina London Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom. Electronic address: verity@betterley.co.uk.
2 Complex Motor Disorders Service, Evelina London Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom.