The American Society of Anesthesiologists Postoperative Visual Loss Registry: analysis of 93 spine surgery cases with postoperative visual loss

BACKGROUND: Postoperative visual loss after prone spine surgery is increasingly reported in association with ischemic optic neuropathy, but its etiology is unknown. METHODS: To describe the clinical characteristics of these patients, the authors analyzed a retrospectively collected series of 93 spine surgery cases voluntarily submitted to the American Society of Anesthesiologists Postoperative Visual Loss Registry on standardized data forms. RESULTS: Ischemic optic neuropathy was associated with 83 of 93 spine surgery cases. The mean age of the patients was 50 +/- 14 yr, and most patients were relatively healthy. Mayfield pins supported the head in 16 of 83 cases. The mean anesthetic duration was 9.8 +/- 3.1 h, and the median estimated blood loss was 2.0 l (range, 0.1-25 l). Bilateral disease was present in 55 patients, with complete visual loss in the affected eye(s) in 47. Ischemic optic neuropathy cases had significantly higher anesthetic duration, blood loss, percentage of patients in Mayfield pins, and percentage of patients with bilateral disease compared with the remaining 10 cases of visual loss diagnosed with central retinal artery occlusion (P < 0.05), suggesting they are of different etiology. CONCLUSIONS: Ischemic optic neuropathy was the most common cause of visual loss after spine surgery in the Registry, and most patients were relatively healthy. Blood loss of 1,000 ml or greater or anesthetic duration of 6 h or longer was present in 96% of these cases. For patients undergoing lengthy spine surgery in the prone position, the risk of visual loss should be considered in the preoperative discussion with patients.     

The American Society of Anesthesiologists Postoperative Visual Loss Registry: Analysis of 93 Spine Surgery Cases with Postoperative Visual Loss

Background: Postoperative visual loss after prone spine surgery is increasingly reported in association with ischemic optic neuropathy, but its etiology is unknown.

Methods: To describe the clinical characteristics of these patients, the authors analyzed a retrospectively collected series of 93 spine surgery cases voluntarily submitted to the American Society of Anesthesiologists Postoperative Visual Loss Registry on standardized data forms.

Results: Ischemic optic neuropathy was associated with 83 of 93 spine surgery cases. The mean age of the patients was 50 +/- 14 yr, and most patients were relatively healthy. Mayfield pins supported the head in 16 of 83 cases. The mean anesthetic duration was 9.8 +/- 3.1 h, and the median estimated blood loss was 2.0 l (range, 0.1-25 l). Bilateral disease was present in 55 patients, with complete visual loss in the affected eye(s) in 47. Ischemic optic neuropathy cases had significantly higher anesthetic duration, blood loss, percentage of patients in Mayfield pins, and percentage of patients with bilateral disease compared with the remaining 10 cases of visual loss diagnosed with central retinal artery occlusion (P < 0.05), suggesting they are of different etiology.     

Ischemic optic neuropathy following spine surgery

Perioperative visual loss (POVL) is a devastating injury that has been reported infrequently after nonocular surgery. The most common cause of POVL is ischemic optic neuropathy (ION). Increasing numbers of cases of ION are being reported after spine surgery, but the etiology of postoperative ION remains poorly understood. After a MEDLINE search of the literature, we reviewed published case reports of ION, specifically those reported after spine surgery performed with the patient in the prone position. Most of the cases involved posterior ION (PION, n = 17), and the remainder anterior (AION, n = 5). Most patients had no or few preoperative vascular disease risk factors. All except one PION and 2 of 5 AION cases reported symptom onset within the first 24 hours after surgery. Visual loss was frequently bilateral (40% of AION, 47% of PION cases). Mean operative time exceeded 450 minutes. The lowest average intraoperative mean arterial blood pressure was 64 mm Hg and the mean lowest intraoperative hematocrit was 27%. The average blood loss was 1.7 L for AION and 5 L for PION patients. PION patients received an average of 8 L of crystalloid solution and 2.2 L of colloid intraoperatively. This compilation of case reports suggests that a combination of prolonged surgery in the prone position, decreased ocular perfusion pressure, blood loss and anemia/hemodilution, and infusion of large quantities of intravenous fluids are some of the potential factors involved in the etiology of postoperative ION. However, levels of blood pressure and anemia intraoperatively were frequently at levels considered acceptable in anesthesia practice. The etiology of postoperative ION remains incompletely understood. Potential strategies to avoid this complication are discussed.     

Perioperative visual loss after spine surgery

Perioperative visual loss(POVL) is an uncommon, but devastating complication that remains primarily associated with spine and cardiac surgery. The incidence and mechanisms of visual loss after surgery remain difficult to determine. According to the American Society of Anesthesiologists Postoperative Visual Loss Registry, the most common causes of POVL in spine procedures are the two different forms of ischemic optic neuropathy: anterior ischemic optic neuropathy and posterior ischemic optic neuropathy, accounting for 89% of the cases. Retinal ischemia, cortical blindness, and posterior reversible encephalopathy are also observed, but in a small minority of cases. A recent multicenter case control study has identified risk factors associated with ischemic optic neuropathy for patients undergoing prone spinal fusion surgery. These include obesity, male sex, Wilson frame use, longer anesthetic duration, greater estimated blood loss, and decreased percent colloid administration. These risk factors are thought to contribute to the elevation of venous pressure and interstitial edema, resulting in damage to the optic nerve by compression of the vessels that feed the optic nerve, venous infarction or direct mechanical compression. This review will expand on these findings as well as the recently updated American Society of Anesthesiologists practice advisory on POVL. There are no effectivetreatment options for POVL and the diagnosis is often irreversible, so efforts must focus on prevention and risk factor modification. The role of crystalloids versus colloids and the use of α-2 agonists to decrease intraocular pressure during prone spine surgery will also be discussed as a potential preventative strategy.     

Positioning patients for spine surgery: Avoiding uncommon position-related complications

Positioning patients for spine surgery is pivotal for optimal operating conditions and operative-site exposure. During spine surgery, patients are placed in positions that are not physiologic and may lead to complications. Perioperative peripheral nerve injury (PPNI) and postoperative visual loss (POVL) are rare complications related to patient positioning during spine surgery that result in significant patient disability and functional loss. PPNI is usually due to stretch or compression of the peripheral nerve. PPNI may present as a brachial plexus injury or as an isolated injury of single nerve, most commonly the ulnar nerve. Understanding the etiology, mechanism and pattern of injury with each type of nerve injury is important for the prevention of PPNI. Intraoperative neuromonitoring has been used to detect peripheral nerve conduction abnormalities indicating peripheral nerve stress under general anesthesia and to guide modification of the upper extremity position to prevent PPNI. POVL usually results in permanent visual loss. Most cases are associated with prolonged spine procedures in the prone position under general anesthesia. The most common causes of POVL after spine surgery are ischemic optic neuropathy and central retinal artery occlusion. Posterior ischemic optic neuropathy is the most common cause of POVL after spine surgery. It is important for spine surgeons to be aware of POVL and to participate in safe, collaborative perioperative care of spine patients. Proper education of perioperative staff, combined with clear communication and collaboration while positioning patients in the operating room is the best and safest approach. The prevention of uncommon complications of spine surgery depends primarily on identifying high-risk patients, proper positioning and optimal intraoperative management of physiological parameters. Modification of risk factors extrinsic to the patient may help reduce the incidence of PPNI and POVL.     

Visual Loss After Orthopedic Procedures

Perioperative visual loss (PVL) is a very rare and unpredictable complication of surgery performed at distance from the visual pathways, mostly after spine or cardiac procedures. We report 6 consecutive patients with PVL after routine orthopedic procedures (osteosynthesis for complex fracture of the femur [2], total hip arthroplasty [2], hip prosthesis arthroplasty [1], bilateral simultaneous total knee arthroplasty [1]) and reviewed the literature on the subject. An ischemic optic neuropathy was diagnosed in all cases, and visual loss was bilateral in 5 of 6 patients. Partial visual improvement occurred in only 3 of 11 eyes. No specific therapy is available for PVL. Postoperative visual disturbances should prompt without delay an ophthalmic evaluation because emergent correction of anemia, systemic hypotension, or hypovolemia might improve visual prognosis of PVL.     

Ischemic optic neuropathy after lumbar spine surgery

Ischemic optic neuropathy is the most common cause of visual complications after non-ophthalmic surgery. The incidence has varied in different case series, but prone-position spine surgery appears to be involved in most of the reports. We present the case of a 47-year-old woman who developed near total blindness in the left eye following lumbar spine fusion surgery involving the loss of 900 mL of blood. An ophthalmic examination including inspection of the ocular fundus, fluorescein angiography, and visual evoked potentials returned a diagnosis of retrolaminar optic neuropathy. Outcome was poor.     

Spinal surgery and ophthalmic complications: a French survey with review of 17 cases

OBJECTIVES: Ocular complications after spine surgery are incompletely understood and are not as rare as implied by recent publications. In 13 out of 15 published case reports, ocular complications are attributed mainly to compression. But in 66 cases reported in 4 series in the literature, compression seems to play a role in less than 10 cases. However, 3 out of the 4 series lack sufficient detail to support this mechanism clearly. Our objectives were to identify the mechanisms and specific risk factors associated with this devastating complication, to help in prevention. METHODS: A 2-page survey was sent to all French orthopedic centers specializing in spine surgery (28 centers) requesting information regarding any patients who had experienced visual deficits after spine surgery. Respondents were asked to identify presence of commonly cited preoperative risk factors, including ophthalmologic diagnosis and local signs (eyelid or conjunctival edema, periorbital numbness, or paresthesia) and intraoperative risks, such as positioning of the head, to clarify the possible mechanisms. Seventeen patients were thus included. RESULTS: Two main mechanisms were identified. First, ocular compression (9 cases) characterized by a unilateral definitive blindness with local signs due to a central retinal artery occlusion. Second, internal carotid thromboembolism (4 cases) associated with head rotation toward the ipsilateral side, causing an ischemic optic neuropathy with a unilateral partial and potentially regressive visual loss. CONCLUSIONS: The authors propose 2 preventive measures: modification of horseshoe-shaped headrest and precautions with lateral rotation of the head in patients with carotid atheroma.     

Unilateral visual loss after cervical spine surgery

This is a case report of a patient who underwent an uneventful surgery for atlanto-axial dislocation in the prone position, after which he developed painless, unilateral loss of vision in the immediate postoperative period. Based on the ophthalmologic findings a probable diagnosis of ischemic optic neuropathy (ION) was made. Although he recovered his visual acuity completely in 1 month, the visual field defects and color vision abnormalities persisted. Intraoperative anemia, hypotension, with or without vasculopathic risk factors, and prolonged surgery in the prone position have been reported as major risk factors for the development of this complication following spine surgery. However, this healthy young man had an uneventful surgery with no such intraoperative complications. ION in this patient could have been due to a combination of factors, such as a malpositioned horseshoe headrest and surgery performed in the prone position, both of which have the potential to raise the intraocular pressure and lower the perfusion pressure of the optic nerve/nerve head. Variations in the blood supply of the optic nerve due to the presence of watershed zones could be another explanation for this dreaded complication.     

Postoperative blindness

This chapter discusses the cases of postoperative blindness reported in the literature and the theories that attempt to explain the mechanisms involved. Although uncommon, alterations in vision and blindness after anesthesia for major surgical procedures, particularly cardiopulmonary bypass or spine surgery, are well documented, with an incidence varying between 0.05% and 1%. Accurate incidence data are unavailable because it is not known what percentages are reported. However, the large number of case reports over many years has provided some significant information. Although sustained compression of the eye is an important cause, postoperative visual loss may also occur, in an unrelated manner, because of ischemic optic neuropathy, central retinal artery or vein occlusion, or cortical blindness.     

Perioperative risk factors for posterior ischemic optic neuropathy

Background:

Infarction of the optic nerve posterior to the lamina cribrosa, called posterior ischemic optic neuropathy (PION), is a condition that can result in profound bilateral blindness. Cases of PION treated at this institution and those described in the literature were analyzed to identify clinical features that profile those individuals at risk of PION in an attempt to identify major contributing factors that could be addressed prophylactically to enable effective prevention.

Study Design:

Salient clinical features in seven cases of PION diagnosed at the Doheny Eye Institute between 1989 and 1998 are compared with 46 cases of PION reported in the literature.

Results:

In the Doheny series there were six men and one woman aged 12 to 66 years (mean, 47 years). Five patients were status-post spine surgery, one was status-post knee surgery, and one had a bleeding stomach ulcer. Vision loss was simultaneously bilateral in six of seven patients (85.7%) and was apparent immediately after surgery. There were no abnormal retinal or choroidal findings including diabetic retinopathy, in any of the patients. Notable contributing factors were blood loss in all seven patients, ranging from 2,000 to 16,000 mL, with a drop in hematocrit of 9.5% to 19% (mean, 14%), and intraoperative systemic hypotension in all patients. Facial edema was a factor in three of six spine surgery patients (50%). Patients reported in the literature had a mean age of 50 years and were also predominantly men (34 of 46, 74%) who underwent spine surgery (30 of 46, 65.2%).

Conclusions:

Middle-aged men undergoing spine surgery with prolonged intraoperative hypotension and postoperative anemia and facial swelling are at risk of developing PION from hypovolemic hypotension. Avoiding or immediately correcting these contributory factors can reduce the incidence of PION.     

Strategies to prevent ischemic optic neuropathy following major spine surgery: A narrative review

Postoperative vision loss following a major spine operation is a rare but life-changing event. Most of reports have been linked to ischemic optic neuropathy, and patients undergoing surgery for scoliosis correction or posterior lumbar fusion seem to be at the highest risk. Despite that some key risk factors have been identified, much of the pathophysiology still remain unknown. In fact, whereas only a minority of patients at high risk will present this complication, others with similar risk factors undergoing different procedures may not develop it at all. On the other hand, even when all preventive measures have been taken, ischemic optic neuropathy may still occur. Therefore, it is appropriate for clinicians involved in these cases to inform their patients about the existence of a small but unpredictable risk of vision loss. Since ischemic optic neuropathy is deemed to be the leading cause of vision loss in the context of major spine surgery in prone position, this review will be focused on its main aspects related to the frequency, diagnosis, predisposing factors, and prevention. Regrettably, no treatment has been proved to be effective for this condition.     

Erblindung nach nichtophthalmologischen Eingriffen

Background and goal

Postoperative loss of vision is a rare, but devastating complication after non-ocular surgery. It can occur partially or completely and may involve one or both eyes. Since its etiology has not yet been solved, the purpose of this review was to extract potential causes from the case collections reported to propose prophylactic measures.

Methods

A literature search was performed using the “Pubmed” database of the US National Library of Medicine. MeSH terms and combinations used were: blindness, postoperative complications, ischemic optic neuropathy, not ophthalmological surgical procedures, not neurosurgical procedures. Additionally, the results of the interim analysis of the postoperative visual loss (POVL) registry of the ASA were considered.

Results

The incidence of permanent loss of vision after non-ophthalmologic surgery is reported to be 0.0008%. However, it is elevated up to 0.11% after cardiac and 0.08% after spine surgery. Risk factors seem to be perioperative anemia, arterial hypotension and prone position, but also pre-existing diseases such as arteriosclerosis. Thus hemodynamic stabilization or correction of anemia may be successful in therapy.

Conclusion

Patients with pre-existing arteriosclerotic disease scheduled for spine or cardiac surgery, but also for bilateral neck dissection should be informed preoperatively about the rare possibility of POVL. Postoperatively any visual changes should be immediately referred to an ophthalmologist and treated accordingly.     

Radiation-induced optic neuropathy: a magnetic resonance imaging study

Optic neuropathy induced by radiation is an infrequent cause of delayed visual loss that may at times be difficult to differentiate from compression of the visual pathways by recurrent neoplasm. The authors describe six patients with this disorder who experienced loss of vision 6 to 36 months after neurological surgery and radiation therapy. Of the six patients in the series, two had a pituitary adenoma and one each had a metastatic melanoma, multiple myeloma, craniopharyngioma, and lymphoepithelioma. Visual acuity in the affected eyes ranged from 20/25 to no light perception. Magnetic resonance (MR) imaging showed sellar and parasellar recurrence of both pituitary adenomas, but the intrinsic lesions of the optic nerves and optic chiasm induced by radiation were enhanced after gadolinium-diethylenetriaminepenta-acetic acid (DTPA) administration and were clearly distinguishable from the suprasellar compression of tumor. Repeated MR imaging showed spontaneous resolution of gadolinium-DTPA enhancement of the optic nerve in a patient who was initially suspected of harboring recurrence of a metastatic malignant melanoma as the cause of visual loss. The authors found the presumptive diagnosis of radiation-induced optic neuropathy facilitated by MR imaging with gadolinium-DTPA. This neuro-imaging procedure may help avert exploratory surgery in some patients with recurrent neoplasm in whom the etiology of visual loss is uncertain.     

Unusual presentation of perioperative ischemic optic neuropathy following major spine surgery

Perioperative visual loss following spinal surgery has become of increasing concern among anesthesiologists, surgeons, and patients alike. Perioperative ischemic optic neuropathy often occurs in patients greater than 50 years of age, in association with a number of presumed risk factors, including diabetes, hypertension, small cup-to-disc ratio, preoperative anemia, intraoperative hypotension, prolonged operative time in the prone position, and significant blood loss during surgery. The visual loss is notably devastating, and generally leads to permanent disability. A 44-year-old man whose central visual acuity was completely preserved is presented.     

Dysthyroid optic neuropathy without extraocular muscle involvement

We present three atypical cases of dysthyroid optic neuropathy. The unique feature was progressive visual field loss with normal-sized or minimally enlarged extraocular muscles. Other atypical findings included optic nerves that appeared to be linearly on stretch with only moderate proptosis, good ocular motility, and only mildly reduced central visual acuity and color vision despite severe field loss. These cases responded rapidly to decompressive surgery after failing high-dose corticosteroid therapy. While marked enlargement of the extraocular muscles with apical optic nerve compression has been documented to cause dysthyroid optic neuropathy, another etiology such as short optic nerves on stretch appears to be at work in these atypical cases. Although extraocular muscle enlargement is the most important diagnostic feature and indicator of the severity of Graves' ophthalmology, our atypical cases demonstrate that this sign alone is an inadequate basis for diagnosis and visual prognosis.     

Effect of the degree of reverse Trendelenburg position on intraocular pressure during prone spine surgery: a randomized controlled trial

Background contextPostoperative vision loss complicates an estimated 1 in 1,100 prone spine surgical cases. This complication has been attributed to ischemic optic neuropathy, with one proposed reason being perioperative elevations in intraocular pressure (IOP). Previous research has studied the effects of table inclination on IOP in awake volunteers; however, the effects in spine surgery patients have not been investigated for reverse Trendelenburg positioning using a prospective, randomized controlled study design.PurposeTo assess the effect of table inclination on IOP in patients undergoing prone spine surgery.Study designSingle-center, prospective randomized controlled study.Patient sampleNineteen patients with no history of eye pathology, undergoing prone spine surgery at Dwight D. Eisenhower Army Medical Center, were randomly assigned to a table position: neutral, 5°, or 10° of reverse Trendelenburg.Outcome measuresIntraocular pressure, mean arterial pressure (MAP), estimated blood loss, fluid resuscitation, and ophthalmologic complication were assessed before and after induction and at incremental times during surgery, beginning at 30 minutes, 60 minutes, and 60-minute increments thereafter.MethodsMultivariate analyses evaluated surgical time, IOP, MAP, estimated blood loss, and fluid resuscitation as a function of table inclination to determine the effect of patient positioning on identified risk factors for postoperative vision loss.ResultsSurgical times ranged from 33 to 325 minutes. A rapid increase in IOP was noted after prone positioning, with continued increases as time elapsed. The neutral group exhibited statistically higher IOP compared with the 5° reverse Trendelenburg group after 60 minutes and the 10° group through 60 minutes of surgery. The trend continued through 120 minutes; however, because of a lack of power, we were unable to determine the statistical significance. There were no statistically significant differences between the 5° and 10° reverse Trendelenburg groups.ConclusionsReverse Trendelenburg positioning elicits decreased IOP compared with prone positioning for surgery times less than 120 minutes. Ten degrees of reverse Trendelenburg attenuate the rise in IOP during prone spine surgery superiorly in comparison with 5°. No significant complications were associated with reverse Trendelenburg positioning.     

Delayed visual deterioration after pituitary surgery--a review introducing the concept of vascular compression of the optic pathways

BACKGROUND: Delayed visual deterioration after pituitary surgery has been attributed to secondary empty sella syndrome and downward herniation of the optic nerves and chiasm, but the pathophysiological basis of this condition is still a matter of debate. REVIEW: According to the literature, prior radiation therapy, previous visual impairment and transcranial surgery constitute risk factors for delayed visual deterioration. Radiation-induced vascular changes and/or strangulation of the optic nerves or chiasm are thought to compromise local blood flow. Downward herniation of the optic pathways was present in the majority of cases, but did not correlate with visual symptoms and signs, while dense scarring of the chiasm was a reproducable finding in all surgically explored cases. Indentations in the upper margin of the optic nerves or chiasm caused by the A1 segments of the anterior cerebral arteries have been reported repeatedly. As perichiasmal scarring constitutes the most consistent finding, the intimate relationship between artery and nerve with consecutive pulsatile pressure may constitute a causative factor in delayed visual dysfunction after pituitary surgery. The authors therefore introduce the concept of vascular compression, which is illustrated with a personal case of a successful decompression procedure with teflon interposition between the A1 segment and the non-herniated optic nerve to treat visual loss eight months following removal of a hemorrhagic pituitary adenoma. CONCLUSIONS: Clinicians should be aware that surgical exploration via a transcranial approach is indicated in cases of progressive visual loss late after pituitary surgery, no matter whether downward displacement of the optic pathways is present on imaging studies or not. Special attention should be paid intra-operatively to the dissection of the intimate relationship between the anterior cerebral arteries and the optic nerves and chiasm.     

Visual impairment after laparoscopic donor nephrectomy

Loss of vision after surgery is rare and has never been reported after a laparoscopic procedure. We describe a case of visual deficits secondary to posterior ischemic optic neuropathy after a laparoscopic donor nephrectomy. The potential etiologies of postoperative visual loss are reviewed, and recommendations for avoiding this complication are discussed.     

Intra-orbital decompression of teh optic nerve by opening the peri-optic meninges in the treatment of severe optic neuropathies complicating benign intracranial hypertension]

Papilledema from benign intracranial hypertension can cause severe loss of visual acuity and visual field, with an optic neuropathy. We report a study of 5 patients with benign intracranial hypertension, and severe visual loss (visual field loss and visual acuity reduced to 1/10 or less) not improved by medical therapy (acetazolamide). We performed unilateral orbital decompression of the optic nerve sheath. No major operative complication was noted. Follow-up ranged from 11 months to 23 months, with an average of sixteen months. Visual function improvement was noted within 3 months after operation in 4 patients (for 2 eyes on the surgical side improvement of 2/10 and 5/10, for 3 eyes on the opposite surgical side average improvement of 4.6/10). The other patient showed improvement, but no significant. Optic nerve sheath decompression in benign intracranial hypertension seems to be a safe procedure and a therapeutic option in the management of raised intracranial pressure complicated by optic neuropathy with severe visual loss.