1. Hospital Dr. Mario Gatti, Campinas, São Paulo, Brazil
2. Department of Neurosurgery, Hospital Municipal Dr. Mário Gatti, Campinas, São Paulo, Brazil
3. Department of Neurosurgery, Hospital Santa Casa de Limeira, Limeira, São Paulo, Brazil
4. Department of Neurosurgery, Universidade Estadual de Campinas (Unicamp), Campinas, São Paulo, Brazil