[1] UCL, Dept Paediat Neurosci, Wolfson Ctr, Inst Child Hlth,Neurosci Unit, London WC1N 2AP, England
[2] Great Ormond St Hosp Sick Children, London WC1N 3JH, England
[3] UCL, Inst Child Hlth, Radiol & Phys Unit, London WC1N 2AP, England
[4] UCL, MRC Ctr Epidemiol Child Hlth, Inst Child Hlth, London WC1N 2AP, England
[5] Natl Ctr Young People Epilepsy, Surrey, England