1 Section of Neurosurgery, Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Palermo, Italy. Electronic address: giovanni.grasso@unipa.it.
2 Department of Neurology and Psychiatry, Neurosurgery, "Sapienza" University of Rome, Rome, Italy.
3 Department of Neurosurgery, University of Messina, Messina, Italy.