[1] ROYAL VICTORIA HOSP,DEPT NEUROSURG,BELFAST BT12 6BA,NORTH IRELAND
[2] ATKINSON MORLEYS HOSP,DEPT NEUROSURG,LONDON SW20,ENGLAND
[3] BROOK GEN HOSP,REG NEUROSURG UNIT,LONDON SE18 4LW,ENGLAND
[4] UNIV HELSINKI,DEPT NEUROSURG,SF-00100 HELSINKI 10,FINLAND
[5] ADDENBROOKES HOSP,DEPT NEUROSURG,CAMBRIDGE CB2 2QQ,ENGLAND
[6] REG NEUROL CTR,DEPT NEUROSURG,NEWCASTLE TYNE,ENGLAND
[7] UNIV GLASGOW,DEPT SURG,GLASGOW G12 8QQ,SCOTLAND
[8] UNIV NOTTINGHAM,CTR CLIN TRIAL DATA,NOTTINGHAM NG7 2RD,ENGLAND