1 Department of Neurosurgery, University Hospital of Wales, CF14 4XW Cardiff, United Kingdom. Electronic address: [email protected].
2 Department of Spinal Neurosurgery, Neuromodulation & Surgery for Handicap, Poitiers University Hospital, CHU of Poitiers, 6, rue de la Milétrie, 86000 Poitiers, France.
3 School of Biomedical Sciences, University of Newcastle, University Drive, 2308 Callaghan, NSW, Australia.