[1] Univ Barcelona, Fac Med, Dept Neurosurg, Hosp Clin, Barcelona 7, Spain
[2] Univ Barcelona, Fac Med, Lab Surg Neuroanat LSNA, Barcelona 7, Spain
[3] Univ Naples Federico II, Dept Neurol Surg, Div Neurosurg, Naples, Italy
[4] Univ Barcelona, Fac Med, Dept Otorhinolaryngol, Rhinol Unit,Hosp Clin Barcelona, Barcelona 7, Spain
[5] Inst Invest Biomed August Pi & Sunyer IDIBAPS, Dept Brain Ischemia & Neurodegenerat, Consejo Super Invest Cient CSIC, Barcelona, Spain
[6] Univ Barcelona, Fac Med, Dept Radiol, Neuroradiol Div,Hosp Clin, Barcelona 7, Spain