[1] Charing Cross Hosp, Dept Neurosurg, London W6 8RF, England
[2] Charing Cross Hosp, Dept Infect Dis, London W6 8RF, England
[3] Charing Cross Hosp, Dept Neuroanaesthesia, London W6 8RF, England
[4] John Radcliffe Hosp, Dept Neurosurg, Oxford OX3 9DU, England