[1] Hop La Pitie Salpetriere, Dept Neurosurg, F-75651 Paris 13, France
[2] Hosp Badalona Germans Trias & Pujol, Dept Neurosurg, Barcelona 08916, Spain
[3] Hop La Pitie Salpetriere, INSERM, UMR S678, F-75651 Paris 13, France
[4] Bellvitge Hosp, Dept Prevent Med & Publ Hlth, Barcelona 08907, Spain