1. Department of Neurosurgery, Hospital Getulio Vargas, Recife, Pernambuco, Brazil.
2. Department of Neurosurgery, Universidade Federal do Vale do São Francisco, Petrolina, Pernambuco, Brazil.
3. Department of Neurosurgery, Rede D’Or Sao Luiz, Recife, Pernambuco, Brazil.