[1] Univ Newcastle Upon Tyne, Sch Med, Sch Neurol Neurobiol & Psychiat, Newcastle Upon Tyne NE2 4HH, Tyne & Wear, England
[2] Univ Halle Wittenberg, Dept Neurol, Halle Saale, Germany
[3] Columbia Univ, Coll Phys & Surg, Dept Neurol, New York, NY USA
[4] Univ Oulu, Dept Neurol, Oulu, Finland
[5] Univ Gottingen, Dept Paediat & Neuropaediat, D-3400 Gottingen, Germany
[6] Royal Childrens Hosp, Murdoch Childrens Res Inst, Melbourne, Vic, Australia