1. Neurosurgical Trials Group, Newcastle University, Newcastle upon Tyne, UK
2. Neurosurgery, Queen Elizabeth Hospital, Birmingham, UK
3. Neuroradiology, Queen Elizabeth University Hospital, Glasgow, UK
4. Health Research Group, Lincoln University, Lincoln, UK
5. Neurosurgery, South Tees Hospitals NHS Foundation Trust, UK
6. Neurosurgery, Queen Elizabeth University Hospital, Glasgow, UK
7. Neuroradiology, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle, UK
8. University Hospitals Plymouth NHS Trust, Plymouth, UK