^a JH is at The National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK. ME is at the Cleveland Clinic Foundation, Cleveland, Ohio, USA. KL is at the Department of Neurology, University of Minnesota, Minneapolis, USA. FCS-L is at Hospital Quinta d’Or, Rio de Janeiro, Brazil. KR is at the Department of Neurology, Medical University, Lublin, Poland. HK is at the Department of Neurology, Medical University, Warsaw, Poland. FC is at the Clinica Neurologica, Univerisita’ Vita E Salute San Raffaele, Milano, Dipartimento Di Neuroscienze, Università Degli Studi Di Perugia, Italy. JMLL is at the Serviço de Neurologia Hospital Geral de Santo António, Porto, Portugal