Atef Ben Nsir1, Quoc-Anh Thai2, Adnene Boubaker3, Hafedh Jemel4. 1. Department of Neurosurgery, Fattouma Bourguiba University Hospital - The University of Medicine of Monastir, Monastir, Tunisia. 2. Department of Neurosurgery, The Johns Hopkins Hospital - The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. 3. Department of Neurosurgery, The Tunisian National Institute of Neurology - Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia. 4. Department of Neurosurgery, The n National Institute of Neurology - Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia.