1. Department of Neurosurgery, Percy Military Teaching Hospital , Clamart Cedex 92140, France
2. Department of Urology, Bégin Military Teaching Hospital , Saint Mandé Cedex 94160, France
3. Department of Orthopedics, Edouard Herriot Hospital , Lyon Cedex 69003, France
4. Department of Anesthesiology and Reanimation, Edouard Herriot Hospital , Lyon Cedex 69003, France