[1] Western Gen Hosp, Dept Clin Neurosci, Edinburgh, Midlothian, Scotland
[2] Univ Edinburgh, Ctr Clin Brain Sci, Edinburgh, Midlothian, Scotland
[3] Aberdeen Royal Infirm, Dept Neurosurg, Aberdeen, Scotland
[4] Walton Ctr NHS Fdn Trust, Dept Neurosurg, Liverpool, Merseyside, England
[5] Derriford Hosp, South West Neurosurg Ctr, Plymouth, Devon, England
[6] Queens Med Ctr, Ctr Spinal Studies & Surg, Nottingham, England
[7] Royal Victoria Hosp, Dept Trauma & Orthopaed, Belfast, Antrim, North Ireland