1 Division of Neurosurgery, Department of Neurology, Hospital das Clínicas da Faculdade de Medicina, University of São Paulo, São Paulo 03·178-200, Brazil. Electronic address: davi.solla@hc.fm.usp.br.
2 Neurosciences Institute, El Bosque University, Bogotá, Colombia.
3 Division of Neurosurgery, Department of Neurology, Hospital das Clínicas da Faculdade de Medicina, University of São Paulo, São Paulo 03·178-200, Brazil.