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Show PHOTO ESSAY Dilated Superior Ophthalmic Veins and Posterior Ischemic Optic Neuropathy After Prolonged Spine Surgery Ashvini Reddy, MD, Rod Foroozan, MD, Jane C. Edmond, MD, and Lisa K. Hinckley, MD FIG. 1. Postcontrast T1 axial (A) and coronal (B) orbit MRI studies performed 19 hours after prolonged prone position lumbar spine surgery show markedly dilated superior ophthalmic veins. Five months after the surgery, axial (C) and coronal (D) studies show normalization in the caliber of the superior ophthalmic veins. Abstract: A 55-year-old man developed bilateral posterior ischemic optic neuropathy after prolonged prone position lumbar laminectomy. Brain MRI performed 19 hours after the procedure revealed markedly dilated superior ophthalmic veins, a finding that had disappeared on a comparable study per-formed 5 months later. This first report of dilated superior ophthalmic veins present in the immediate postoperative period but not later may be important in suggesting that an increase in orbital venous pressure during surgery contributes to the development of postoperative posterior ischemic optic neuropathy (PION). (J Neuro-Ophthalmol 2008;28:327-328) Department of Ophthalmology (RA, RF, JCE), Baylor College of Medicine Houston, Texas; and Department of Radiology (LKH), Methodist Hospital Houston, Texas. Address correspondence to Rod Foroozan, MD, 6565 Fannin NC-205, Houston, TX 77030; E-mail: foroozan@bcm.tmc.edu A55-year-old man underwent a 4.5-hour but otherwise uncomplicated lumbar laminectomy for lumbar steno-sis in the prone position and complained of painless decreased vision in both eyes upon recovery from anes-thesia. He had had an estimated blood loss of 900 mL and a postoperative hemoglobin of 11.6 g/dL. He had required 3600 mL of crystalloid and 500 mL of colloid and had had an intraoperative urine output of 200 mL. The lowest recorded intraoperative blood pressure had been 90/50 mmHg. His medical history included fibromyalgia, chronic fatigue, gout, sleep apnea, degenerative joint disease, peripheral neuropathy, benign prostatic hypertrophy, ath-erosclerosis, and previous lumbar spine surgery. He had undergone coronary artery bypass surgery 1 year earlier. On the first postoperative day, visual acuity was counting fingers in the right eye and hand movements in the left eye. There was no facial edema. Confrontation visual fields confirmed dense central scotomas bilaterally. Color vision tested with Ishihara pseudoisochromatic plates was absent in each eye. Pupils measured 3.5 mm in dim 327 J Neuro-Ophthalmol, Vol. 28, No. 2, 2008 Reddy et al illumination and constricted sluggishly to light without a relative afferent pupillary defect. Ophthalmoscopic exami-nation revealed normal optic discs. The retina appeared normal without venous dilation. We made a presumptive diagnosis of bilateral posterior ischemic optic neuropathy (PION) and attributed it to prolonged prone position spine surgery. Brain MRI performed 19 hours after the procedure surprisingly revealed dilated superior ophthalmic veins (Fig. 1A-B) on each side with no compressive lesions and no optic nerve enhancement. There was no suggestion of intracranial hypotension or engorgement of the dural venous sinuses. The cavernous sinuses were normal. One day later, visual evoked potentials showed no responses from either eye. Examination 4 weeks later revealed diffusely pale optic discs without cupping in both eyes. Visual acuity had improved to 20/25 in the right eye and 20/20 in the left eye, but with severely constricted visual fields on automated perimetry. Otherwise the neuro-ophthalmologic examina-tion remained unchanged. Repeat MRI of the brain and orbits 5 months postoperatively showed normal caliber of the superior ophthalmic veins (Fig. 1C-D). There was no clinical evidence of an arteriovenous fistula and results of brain magnetic resonance venography (MRV) were normal. Hemodynamic derangements in arterial perfusion pressure, orbital venous pressure, and blood oxygen-carrying capacity are thought to be key factors in the development of postoperative PION (1,2). Of these three factors, increased orbital venous pressure is the most dif-ficult to document, and therefore its role in the pathogenesis of PION has been the most difficult to ascertain. The prone position, jugular vein ligation, increased cerebrospinal fluid (CSF) pressure, orbital edema, and the Trendelenburg (dependent head) position have all been implicated as factors that could lead to increased orbital venous pressure (3-12). To our knowledge, this is the only patient with postoperative PION to demonstrate dilated superior oph-thalmic veins on MRI in the acute setting and a reduction in venous caliber over time, suggesting an association between an increase in orbital venous pressure during surgery and the development of PION. A study of the effect of prolonged prone positioning on the caliber of the superior ophthalmic veins might help determine whether increased orbital venous pressure plays a role in postoperative PION. REFERENCES 1. Buono LM, Foroozan R. Perioperative posterior ischemic optic neuropathy: review of the literature. Surv Ophthalmol 2005;50:15-26. 2. Hayreh SS. Posterior ischaemic optic neuropathy: clinical features, pathogenesis, and management. Eye 2004;18:1188-206. 3. Alexandrakis G, Lam BL. Bilateral posterior ischemic optic neuropathy after spinal surgery. Am J Ophthalmol 1999;127:354-5. 4. Balm AJ, Brown DH, De Vries WA, et al. 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