1 Department of Neurosurgery, Poitiers University Hospital, 2, rue de la Milétrie, 86000 Poitiers, France. Electronic address: philipperigoard@yahoo.fr.
2 Neurosurgery Department, Roger-Salengro Teaching Hospital, CHRU de Lille, 59037 Lille, France. Electronic address: r-assaker@chru-lille.fr.