Postoperative ischemic optic neuropathy

Study Design. Systematic literature review. Objective. To determine if there are predictors or preventative measures for postoperative ischemic optic neuropathy (ION) associated with spine surgery. Summary of Background Data. Postoperative ION is a devastating complication that is most common after cardiac and spinal fusion surgery. Identifying patient or perioperative predictors for postoperative ION could lead to therapeutic modifications designed to minimize its occurrence. Methods. A systematic literature review was conducted in MEDLINE, EMBASE, and the Cochrane Collaboration Library for literature published in English from 1990 through 2008 reporting on ION following spine surgery. References from review articles of ION were used, but articles without original material were excluded. Data on study design, patient demographics, and perioperative characteristics were collected and analyzed. Two independent reviewers assessed the strength of literature using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria assessing quality, quantity, and consistency of results. Disagreements were resolved by consensus. Results. Nineteen of 360 articles on postoperative ION after spine surgery met inclusion/exclusion criteria. The quality of evidence was very low as the majority of articles were case reports. The majority of ION patients were men between 30 and 69 years, undergoing spinal fusion surgery with an operative duration greater than 5 hours and an estimated blood loss greater than 1 L. Confounding factors and lack of a denominator from the case reports and case series precluded identification of risk factors with even a modest level of evidence. Conclusion. Postoperative ION after spinal surgery is a rare event, which may be associated with prone position surgery of more than 5 hours surgical duration and blood loss of more than 1 L. Informing patients of this remote risk should be considered during preoperative counseling. The quality of evidence for preventative measures for postoperative ION after spinal fusion surgery is very low, but it has been proposed that efforts aimed at reducing the duration or severity of venous congestion in the head may be beneficial.