[1] Hosp Geral Santo Antonio, Serv Neurol, Dept Neurol, PT-4099001 Oporto, Portugal
[2] Hosp Geral Santo Antonio, Dept Neuroradiol, PT-4099001 Oporto, Portugal
[3] Univ Porto, Inst Patol & Imunol Mol, P-4100 Oporto, Portugal
[4] Univ Porto, ICBAS, Populat Study Dept, P-4100 Oporto, Portugal