1 Neurosurgical Unit, Department of Biomedicine, Neurosciences and Advanced Diagnostics, University of Palermo, Palermo, Italy. Electronic address: giovanni.grasso@unipa.it.
2 Rehabilitation Medicine Outpatient Department, A.S.P. Palermo, Palermo, Italy.
3 Department of Spine Surgery, Nanoori Gangnam Hospital, Seoul, South Korea.
4 Neurosurgical Unit, Department of Biomedicine, Neurosciences and Advanced Diagnostics, University of Palermo, Palermo, Italy.