Ischaemic optic neuropathy after spinal fusion.

We report a case of ischaemic optic neuropathy which occurred after prolonged spine surgery in the prone position in an obese, diabetic patient. The patient was a 44-yr-old, 123 kg, 183 cm man for decompressive laminectomy and instrumented fusion of the lumbar spine. Anaesthesia was induced with thiopentone, fentanyl and succinylcholine and maintained with nitrous oxide, oxygen, isoflurane and a fentanyl infusion. He was positioned prone on the Relton-Hall frame and had an uneventful intraoperative course. Estimated blood loss was 3,000 ml. He was taken to the surgical intensive care unit (SICU) and the trachea was extubated 3.5 hr later. He had no pulmonary or haemodynamic problems and went to a regular nursing floor in the morning. He was discharged home on postoperative day #5. He telephoned his surgeon on postoperative day #7 to say that his vision had been blurry since surgery. His visual acuity was decreased, and on examination, he had a bilateral papillary defect, optic swelling and a splinter haemorrhage in the right eye. Magnetic resonance imaging (MRI) scan of the head and orbits detected no other abnormality. Based on this examination, he was felt to have bilateral ischaemic optic neuropathy and treated conservatively. By postoperative day #47, his visual acuity was greatly improved and near normal. Careful review of possible contributing factors suggests that the cause of the ischaemic optic neuropathy was venous engorgement. This patient developed ischaemic optic neuropathy from a prolonged interval in the prone position of the Relton-Hall frame, which may be related to venous engorgement. Nous rapportons un cas de neuropathie optique ischemique consecutive a une chirurgie rachidienne prolongee en decubitus ventral chez un obese diabetique. Un patient de 44 ans, pesant 123 kg et mesurant 183 cm etait opere pour une laminectomie decompressive avec osteosynthese instrumentale de la colonne lombaire. Le thiopental associe a du fentanyl et de la succinylcholine a servi a induire l’anesthesie, qui a ete entretenue avec du protoxyde d’azote, de l’oxygene, de l’isoflurane et une perfusion de fentanyl. Il etait immobilise en decubitus ventral sur un cadre de Relton-Hall et l’operation s’est deroulee sans incident. On a estime la perte sanguine a 3000 ml. Il a ete transfere a l’unite des soins intensifs (USI) et extube 3,5 h plus tard. Il ne presentait aucun probleme respiratoire et hemodynamique et on l’a ramene dans son unite de soins le lendemain matin. Il etait libere le cinquieme jour. Par telephone, il avisait son chirurgien le septieme jour que sa vision etait embrouillee depuis l’intervention. Son acuite visuelle avait diminue et a l’examen, il presentait une lesion papillaire bilaterale, de l’oedeme du nerf optique et une hemorragie lineaire de l’oeil droit. L’imagerie par resonance magnetique de la tete et des orbites ne montrait aucune autre anomalie. Cet examen suggerait une neuropathie optique ischemique bilaterale qui fut traitee de facon conservatrice. Le 47e jour postoperatoire, son acuite visuelle s’etait amelioree considerablement et etait presque redevenue normale. Parmi les facteurs contributoires possibles cette neuropathie ischemique, il faut retenir l’engorgement veineux. A la suite d’une immobilisation prolongee en decubitus ventral sur un cadre de Relton-Hall, ce patient a presente une neuropathie optique par ischemie causee vraisemblablement par engorgement veineux.