1. Department of Neurophysiology Istituto Nazionale Neurologico C. Besta, Milan
2. Department of Neurosurgery, Istituto Nazionale Neurologico C. Besta, Milan
3. Department of Neuroradiology, Ospedale Le Molinette, Turin
4. Department of Neuroradiology, Centro Traumatologico Ortopedico, Turin, Italy