1. From the Academic Department of Neurosurgery, Addenbrooke’s Hospital, Cambridge (M.J., M.S., P.J.H., D.K.M., P.J.K.); Aberdeen Royal Infirmary, Grampian University Hospitals Trust, Aberdeen (M.S., P.C.W.); and South West Neurosurgical Unit, Derriford Hospital, Plymouth (P.C.W.), UK.