[1] Addenbrookes Hosp, Div Neurosurg, Cambridge CB2 0QQ, England
[2] Univ Cambridge, Cambridge, England
[3] St George Hosp, Div Neurosurg, London, England
[4] Royal Victoria Infirm, Div Neurosurg, Newcastle Upon Tyne, Tyne & Wear, England
[5] Newcastle Univ, Newcastle Upon Tyne, Tyne & Wear, England
[6] James Cook Univ Hosp, Div Neurosurg, Middlesbrough, Cleveland, England
[7] Univ Hosp Coventry, Div Neurosurg, Coventry, W Midlands, England
[8] Soc British Neurol Surg, London, England
[9] Cardiff Univ, Natl Neurosci & Mental Hlth Res Inst, Inst Psychol Med & Clin Neurosci, Div Neurosurg, Cardiff CF10 3AX, S Glam, Wales
[10] Western Gen Hosp, Div Neurosurg, Edinburgh EH4 2XU, Midlothian, Scotland
[11] Univ Edinburgh, Edinburgh, Midlothian, Scotland