1. Institute of Neurosurgery Asenjo and Department of Neurological Sciences, University of Chile, Providencia, Santiago, Chile
2. Regional Hospital of Puerto Montt, Puerto Montt, Chile
3. Institute of Neurosurgery Asenjo, Providencia, Santiago, Chile
4. Division of Neurological Surgery, University of Uberlandia, Uberlandia, Brazil
5. Division of Neurological Surgery, University of São Paulo School of Medicine, Sao Paulo, Brazil