1. Department of Neurosurgery, Hospital Nacional Guillermo Almenara, Lima, Perú
2. Far East Neurosurgical Institute, Sapporo Teishinkai Hospital, Sapporo, Japan
3. Department of Neurosurgery, Azienda Ospedaliera Universitaria Pisana (AOUP), University of Pisa, Pisa, Italy
4. Medicine Faculty, Hospital Universidad Austral, Buenos Aires, Argentina