[1] Queen Elizabeth Univ Hosp, Inst Neurol Sci, Dept Neurosurg, Glasgow, Scotland
[2] James Cook Univ Hosp, Dept Radiol, Middlesbrough, England
[3] Queen Elizabeth Univ Hosp, Inst Neurol Sci, Dept Neuroradiol, Glasgow, Scotland
[4] Queen Elizabeth Univ Hosp, Inst Neurol Sci, Dept Neurosurg, 1345 Govan Rd, Glasgow, Scotland