1. Department of Neurology1, University Hospital, Leiden, The Netherlands
2. Glaxo Group Research Ltd2, Greenford, Middlesex, UK
3. Department of Neurology3, Royal Victoria Hospital, Newcastle-Upon-Tyne, UK
4. Department of Neurology4, St Boniface General Hospital Winnipeg, Canada
5. Fondazione “Istituto Neurologico C. Mondino” Pavia, Italy