1 Santa Casa, Sao Paulo Medical School, Sao Paulo, Brazil.
2 Division of Neurosurgery, Department of Neurology, University of Sao Paulo Medical School, Sao Paulo, Brazil.
3 Division of Neurosurgery, Department of Neurology, University of Sao Paulo Medical School, Sao Paulo, Brazil. Electronic address: wellingsonpaiva@yahoo.com.br.