Ali Akhaddar1,2, Hassan Baallal3,4. 1. Department of Neurosurgery, Avicenne Military Hospital, 40000, Marrakech, Morocco. akhaddar@hotmail.fr. 2. Mohammed V University, Rabat, Morocco. akhaddar@hotmail.fr. 3. Department of Neurosurgery, Avicenne Military Hospital, 40000, Marrakech, Morocco. 4. Mohammed V University, Rabat, Morocco.