[1] Department of Neurosurgery,
[2] Pontchaillou Hospital,undefined
[3] University of Rennes,undefined
[4] 2,undefined
[5] rue Henri Le Guilloux,undefined
[6] F-35033 Rennes Cedex,undefined
[7] France Tel.: +33-2-99 28 43 21 Fax: +33-2-99 28 41 80,undefined
[8] Department of Neurosurgery,undefined
[9] Larrey Hospital,undefined
[10] University of Angers,undefined
[11] Rue Larrey,undefined
[12] F-49033 Angers Cedex,undefined
[13] France,undefined