1. Homerton University Hospital NHS Foundation Trust, Homerton Row, London E9 6SR, UK
2. DCEE, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK
3. National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
4. North Middlesex University Hospital, Sterling Way, London N18 1QX, UK