1. Department of Neurosurgery, Azienda Ospedaliero Universitaria Pisana (AOUP), University of Pisa, 56100 Pisa, Italy
2. University College of Medical Sciences and GTB Hospital, New Delhi 110095, India
3. Department of Neurosurgery, Russian People’s Friendship University, 121359 Moscow, Russia
4. Royal Melbourne Hospital, Melbourne, VIC 3000, Australia
5. Department of Spinal Surgery, Central Clinical Hospital of the Russian Academy of Sciences, 121359 Moscow, Russia
6. Department of Pathology, Stanford of School of Medicine, Stanford University Medical Centre, Palo Alto, CA 94305, USA