[1] James Cook Univ Hosp, Dept Neurosurg, Middlesbrough, Cleveland, England
[2] Addenbrookes Hosp, Dept Neurosci, Div Neurosurg, Cambridge, England
[3] Univ Cambridge, Cambridge, England
[4] Imperial Coll Healthcare NHS Trust, Dept Neurosurg, London, England
[5] Southampton Univ Hosp, Wessex Neurol Ctr, Dept Neurosurg, Southampton, Hants, England
[6] Univ Southampton, Southampton, Hants, England
[7] Leeds Gen Infirm, Dept Neurosurg, Leeds, W Yorkshire, England
[8] Walton Ctr, Dept Neurosurg, Liverpool, Merseyside, England
[9] Natl Hosp Neurol & Neurosurg, Dept Neurosurg, London WC1N 3BG, England
[10] Royal Victoria Infirm, Dept Neurosurg, Newcastle Upon Tyne, Tyne & Wear, England
[11] Royal London Hosp, Dept Neurosurg, London E1 1BB, England
[12] St George Hosp, Dept Neurosurg, London, England
[13] Royal Hallamshire Hosp, Dept Neurosurg, Sheffield S10 2JF, S Yorkshire, England
[14] John Radcliff Hosp, Dept Neurosurg, Oxford, England
[15] Derriford Hosp, Dept Neurosurg, Plymouth PL6 8DH, Devon, England
[16] Queen Elizabeth Hosp, Dept Neurosurg, Birmingham B15 2TH, W Midlands, England
[17] Queens Hosp, Dept Neurosurg, Romford, Essex, England
[18] Univ Hosp Coventry, Dept Neurosurg, Coventry, W Midlands, England
[19] Univ Newcastle Tyne, Newcastle Neurosurg Trials Unit, Newcastle Upon Tyne, Tyne & Wear, England
[20] Natl Neurosci & Mental Hlth Res Inst, Inst Psychol Med & Clin Neurosci, Cardiff, S Glam, Wales
[21] Soc British Neurol Surg, London, England
[22] Western Gen Hosp, Dept Neurosurg, Edinburgh EH4 2XU, Midlothian, Scotland