Neurologic complications of aortic surgery

Critical Assessment of the Neurological Complications during High-Risk Anesthesia Procedures

Damage to the peripheral and central nervous systems is frequently irreversible. Surgically induced neurological damage and anesthesia may result in catastrophic situations for patients and their families. The incidence of significant neurological complications during the perioperative period is examined in this article. In contrast to other organs like the kidney, heart, liver, lungs, and skeletal system, native neurological function cannot be replaced with artificial parts or devices soon. Ignoring brain function during the perioperative period has been a systemic problem in anesthesiology, even though the central and peripheral nervous systems are crucial. This bold claim is intended to draw attention to the fact that, unlike the circulatory and respiratory systems, which have been routinely monitored for decades, the brain and other neural structures do not have a standard monitoring during surgery and anesthesia. Given that the brain and spinal cord are the principal therapeutic targets of analgesics and anesthetics, this deficiency in clinical care is even more alarming. Organs that are notoriously hard to repair or replace after damage have, up until now, received comparatively little attention. In this article, a succinct overview of five neurological complications associated with surgery and anesthesia is presented. After critically reviewing the literature on the subject, the article is focused to common (delirium), controversial (postoperative cognitive decline), and potentially catastrophic (stroke, spinal cord ischemia, or postoperative visual loss) adverse events in the neurological surgery setting. The findings will increase awareness of major neurological complications to the involved surgical and anesthesia team and enhance preventive and treatment strategies during the perioperative period.

Risk Factors for Spinal Cord Injury during Endovascular Repair of Thoracoabdominal Aneurysm: Review of the Literature and Proposal of a Prognostic Score

Despite recent improvements, spinal cord ischemia remains the most feared and dramatic complication following extensive aortic repair. Although endovascular procedures are associated with a lower risk compared with open procedures, this risk is still significant and must be considered. A combined medical and surgical approach may help to optimize the tolerance of the spinal cord to ischemia. The aim of this review is to describe the underlying mechanism involved in spinal cord injury during extensive endovascular aortic repair, to describe the different techniques used to improve spinal cord tolerance to ischemia-including the prophylactic or curative use of spinal drainage-and to propose our algorithm for spinal cord protection and the rational use of spinal drainage.

Spinal cord injury after open and endovascular repair of descending thoracic aneurysm and thoracoabdominal aortic aneurysm: an updated systematic review and meta-analysis

Background

Spinal cord injury (SCI) is a rare but severe complication after open or endovascular repair of descending thoracic aneurysms (DTAs) or thoracoabdominal aortic aneurysms (TAAAs). This meta-analysis aims to provide a comprehensive assessment of SCI rates and factors associated with SCI.

Methods

A systematic literature search was performed in September 2022 looking for studies on open and/or endovascular repair of DTA and/or TAAA published after 2018, to update the results of our previously published meta-analysis. The primary outcome was permanent SCI. Secondary outcomes were temporary SCI, 30-day and in-hospital mortality, follow-up mortality, postoperative stroke, and cerebrospinal fluid (CSF) drain-related complications. Data were pooled as proportions using inverse-variance weighting.

Results

A total of 239 studies (71 new studies and 168 from our previous meta-analysis) and 61,962 patients were included. The overall pooled rate of permanent SCI was 3.3% [95% confidence interval (CI), 2.9-3.8%]. Open repair was associated with a permanent SCI rate of 4.0% (95% CI, 3.3-4.8%), and endovascular repair was associated with a permanent SCI rate of 2.9% (95% CI, 2.4-3.5%). Permanent SCI was 2.0% (95% CI, 1.2-3.3%) after DTA repair, and 4.7% (95% CI, 3.9-5.6%) after TAAA repair; permanent SCI rate was 3.8% (95% CI, 2.9-5.0%) for Crawford extent I, 13.4% (95% CI, 9.0-19.5%) for extent II, 7.1% (95% CI, 5.7-8.9%) for extent III, 2.3% (95% CI, 1.6-3.5%) for extent IV, and 6.7% (95% CI, 1.7-23.1%) for extent V TAAA aneurysms. The pooled rate of CSF drain related complications was 1.9% (95% CI, 0.8-4.7%) for severe, 0.4% (95% CI, 0.0-4.0%) for moderate, and 1.8% (95% CI, 0.6-5.6%) for minor complications.

Conclusions

Permanent SCI occurs after both endovascular and open DTA or TAAA repairs. Open repairs and TAAA repairs have higher risk of SCI compared with endovascular or DTA repairs. In particular, extent II aneurysms present the highest overall risk of SCI.

Hemodynamic Patterns of Spinal Cord Perfusion in Thoracoabdominal Aortic Aneurysm Repair

Paraplegia in aortic surgery is due to its impact on spinal cord perfusion whose hemodynamic patterns (SCPHP) are not clearly defined. Detailed morphological analysis of vascular network and collateral network modifications within Monro-Kellie postulate due to the fixed theca confines was performed to identify SCPHP. SCPHP may begin with intraspinal "backflow" (I-BF), that is, hemorrhage from anterior and posterior spinal arteries, backward via the connected anterior and posterior radicular medullary arteries, through the increasing diameter and decreasing resistance of segmental arteries (SAs), off their aortic orifices outside vascular network at 0 operative field pressure. The I-BF blood bypasses both intra- and extraspinal capillary networks and causes depressurization (0 diastolic pressure) and full ischemia of dependent spinal cord. When the occlusion of those SAs orifices arrests I-BF, the hemodynamic pattern of intraspinal "steal" (I-S) may take place. The formerly I-BF blood, in fact, is now variably shared between the fraction maintained in its physiological intraspinal network and that keeping flowing as I-S through the extraspinal capillary network. I-S is, however, counteracted by the extraspinal "steal" from the connected mammary/paraspinous-independent extraspinal feeders, all physically competing for the same room left by the missed physiological SA direct aortic blood inflow. Steal phenomenon evolves within the 120-hour time frame of CNm, whose intraspinal anatomical changes may offer the physical basis within the Monro-Kelly postulate, respectively of the intraoperative and postoperative paraplegia. The current procedures could not prevent the unphysiological SCPHP but awareness of details of their various features may offer the basis for improvements tailored, to the adopted intra- and postoperative procedures.

Trends in the use of cerebrospinal drains and outcomes related to spinal cord ischemia after thoracic endovascular aortic repair and complex endovascular aortic repair in the Vascular Quality Initiative database

BACKGROUND

Spinal cord ischemia (SCI) is a dreaded complication of thoracic and complex endovascular aortic repair (TEVAR/cEVAR). Controversy exists surrounding cerebrospinal fluid drain (CSFD) use, especially preoperative prophylactic placement, owing to concerns regarding catheter-related complications. However, these risks are balanced by the widely accepted benefits of CSFDs during open repair to prevent and/or rescue patients with SCI. The importance of this issue is underscored by the paucity of data on CSFD practice patterns, limiting the development of practice guidelines. Therefore, the purpose of the present analysis was to evaluate the differences between patients who developed SCI despite preoperative CSFD placement and those treated with therapeutic postoperative CSFD placement.

METHODS

All elective TEVAR/cEVAR procedures for degenerative aneurysm pathology in the Society for Vascular Surgery Vascular Quality Initiative from 2014 to 2019 were analyzed. CSFD use over time, the factors associated with preoperative prophylactic vs postoperative therapeutic CSFD placement in patients with SCI (transient or permanent), and outcomes were evaluated. Survival differences were estimated using the Kaplan-Meier method.

RESULTS

A total of 3406 TEVAR/cEVAR procedures met the inclusion criteria, with an overall SCI rate of 2.3% (n = 88). The SCI rate decreased from 4.55% in 2014 to 1.43% in 2018. Prophylactic preoperative CSFD use was similar over time (2014, 30%; vs 2018, 27%; P = .8). After further exclusions to evaluate CSFD use in those who had developed SCI, 72 patients were available for analysis, 48 with SCI and prophylactic CSFD placement and 24 with SCI and therapeutic CSFD placement. Specific to SCI, the patient demographics and comorbidities were not significantly different between the prophylactic and therapeutic groups, with the exception of previous aortic surgery, which was more common in the prophylactic CSFD cohort (46% vs 23%; P < .001). The SCI outcome was significantly worse for the therapeutic group because 79% had documented permanent paraplegia at discharge compared with 54% of the prophylactic group (P = .04). SCI patients receiving a postoperative therapeutic CSFD had had worse survival than those with a preoperative prophylactic CSFD (50% ± 10% vs 71% ± 9%; log-rank P = .1; Wilcoxon P = .05).

CONCLUSIONS

Prophylactic CSFD use with TEVAR/cEVAR remained stable during the study period. Of the SCI patients, postoperative therapeutic CSFD placement was associated with worse sustained neurologic outcomes and overall survival compared with preoperative prophylactic CSFD placement. These findings highlight the need for a randomized clinical trial to examine prophylactic vs therapeutic CSFD placement in association with TEVAR/cEVAR.

Health care costs of endovascular compared with open thoracoabdominal aortic aneurysm repair

OBJECTIVE

To compare 1-year health care costs between endovascular and open thoracoabdominal aortic aneurysm (TAAA).

METHODS

Population-based administrative health databases were used to capture TAAA repairs performed in Ontario, Canada, between January 2006 and February 2017. All health care costs incurred by the Ministry of Health from a single-payer universal health care system were included. Costs of the aortic endografts and ancillary devices for the index procedure were estimated as C$44,000 per endovascular case vs C$1000 for open cases, based on previous reports. Costs (2017 Canadian dollars) were calculated in phases (1, 1-3, 3-6, and 6-12 months from surgery) with censoring for death. For each phase, propensity score matching of endovascular and open cases based on preoperative patient and hospital characteristics was used. The association between preoperative characteristics (including repair approach) and the first month postprocedure cost was characterized through multivariable analysis.

RESULTS

Overall 664 TAAA repairs were identified (open, n = 361 [54.5%] and endovascular, n = 303 [45.6%]). At 1 month, the median cost was higher for endovascular TAAA repair in the prematching cohort (C$64,892 vs C$36,647; P < .01). Similarly, in 241 well-balanced endovascular/open patient pairs after propensity score matching, the median health care costs were higher in endovascular TAAA cases during the first month (C$62,802 vs C$33,605; P < .01). The 1- to 3-month median cost was not statistically different between endovascular and open TAAA cases either before matching (C$2781 vs C$2618; P = .71) or after matching (C$2762 vs C$2092; P = .58). Likewise, in the 3- to 6-month and 6- to 12-month postprocedure intervals, there were no significant differences in the median health care costs between groups. On multivariable analysis, older age (5-year increments) (relative change [RC] in mean cost, 1.05; 95% confidence interval [CI], 1.04-1.06; P = .01), urgent procedures (RC, 1.29; 95% CI, 1.10-1.52; P < .01), and history of stroke (RC, 1.34; 95% CI, 1.00-1.78; P = .05) were associated with higher costs in the first postoperative month, whereas open relative to endovascular TAAA repair was associated with a decreased 1-month cost (RC, 0.65; 95% CI, 0.56-0.74; P < .01).

CONCLUSIONS

TAAA repair is expensive regardless of technique. Compared with open TAAA repair, endovascular repair was associated with a higher early cost, owing to the upfront cost of the endograft and aortic ancillary devices. There was no difference in cost from 1 to 12 months after repair. A decrease in the cost of endovascular devices might allow equivalent costs between endovascular and open TAAA repair.

Systematic review of contemporary outcomes of endovascular and open thoracoabdominal aortic aneurysm repair

OBJECTIVE

The purpose of the study was to provide a systematic review of the literature reporting the contemporary early outcomes after endovascular and open repair of thoracoabdominal aortic aneurysms (TAAAs).

METHODS

MEDLINE and Embase were searched for studies from January 2006 to March 2018 that reported either endovascular (using branched or fenestrated endografts) or open repair of TAAA in at least 10 patients. Outcomes of interest included perioperative mortality, spinal cord injury (SCI), renal failure requiring dialysis, and stroke. Pooled proportions were determined using a random-effects model.

RESULTS

The analysis included 71 studies, of which 24 and 47 reported outcomes after endovascular and open TAAA repair, respectively. Endovascular cohort patients were older and had higher rates of coronary artery disease, chronic obstructive pulmonary disease, and diabetes. Endovascular repair was associated with higher rates of SCI (13.5%; 95% confidence interval [CI], 10.5%-16.7%) compared with open repair (7.4%; 95% CI, 6.2%-8.7%; P < .01) but similar rates of permanent paralysis (5.2% [95% CI, 3.8%-6.7%] vs 4.4% [95% CI, 3.3%-5.6%]; P = .39), lower rates of postoperative dialysis (6.4% [95% CI, 3.2%-9.5%] vs 12.0% [95% CI, 8.2%-16.3%]; P = .03) but similar rates of being discharged on permanent dialysis (3.7% [95% CI, 2.0%-5.9%] vs 3.8% [95% CI, 2.9%-5.3%]; P = .93), a trend to lower stroke (2.7% [95% CI, 1.9%-3.6%] vs 3.9% [95% CI, 3.0%-4.9%]; P = .06), and similar perioperative mortality (7.4% [95% CI, 5.9%-9.1%] vs 8.9% [95% CI, 7.2%-10.9%]; P = .21).

CONCLUSIONS

This systematic review summarizes the contemporary literature results of endovascular and open TAAA repair. Endovascular repair studies included patients with more comorbidities and were associated with higher rates of SCI but similar rates of permanent paraplegia, whereas open repair studies had higher rates of postoperative dialysis but similar rates of being discharged on permanent dialysis. Perioperative mortality rates were similar. Universally adopted reporting standards for patient characteristics, outcomes, and the conduct of contemporary comparative studies will allow better assessment and comparisons of the risks associated with the two surgical treatment options for TAAA.

Is endovascular repair the first choice for all blunt aortic injury? A real-world assessment

Blunt thoracic aortic injury (BTAI) represents an infrequently encountered but lethal traumatic injury. Minimal aortic injuries are appropriately treated by medical management, while more severe injuries require endovascular or open repair. Rapidly evolving endovascular technology has largely supplanted open repair as first line operative intervention, however, the complexity of the severely injured blunt trauma patient can complicate management decisions. The development and implementation of an optimal consensus grading system and treatment algorithm for the management of BTAI is necessary and will require multi-institutional study.

Review of the History of Non-traumatic Spinal Cord Dysfunction

Background: The incidence of non-traumatic spinal cord dysfunction (SCDys) is reported to be higher than traumatic spinal cord injury (SCI) in many countries. No formal review of the history of SCDys has been published. Objective: This article aims to identify key highlights in the history of SCDys. Method: An electronic literature search was conducted (January 2017) using MEDLINE (1946-2016) and Embase (1974-2016) databases for publications regarding the history of SCDys. Publications on the history of SCI and a selection of neurology textbooks and books on the history of neurology were reviewed for potentially relevant references. The focus of the literature search was on identifying publications that detail key highlights regarding the history of the diagnosis and management of the most common SCDys conditions, as well as those of historical significance. Results: The electronic search of MEDLINE and Embase identified 11 relevant publications. The majority of publications included were identified from the authors' libraries and a selection of books on neurology and the history of neurology. Conclusions: This review outlines the history of SCDys, taking a broader historical perspective and covering the increasing awareness of the role of the spinal cord and knowledge of neuroanatomy. Key milestones in the history of the diagnosis and management of the most common SCDys conditions are presented. An appreciation of the history of SCDys increases our understanding of the large number of people who contributed to our current knowledge of these conditions and in some situations helps guide efforts regarding prevention of SCDys.

Controversies in the Surgical Treatment of Thoracic Aortic

The author recommends echocardiography and thoracic aortography com bined with coronary angiography in patients with thoracic aortic aneurysms prior to the operation; resection and replacement of asymptomatic fusiform aneurysms measuring twice or more the size of the normal aorta and of aortic dissections at cardiac operations; and use of active shunts during resection of descending thoracic aneurysms.

Electrophysiologic Monitoring during Surgery to Repair the Thoracoabdominal Aorta

The repair of aneurysms and dissections that involve the thoracoabdominal aorta represent a major stress to the cardiovascular surgery team because of the feared complication of paraplegia. Here, the etiology of this complication is explained through a description of the relevant surgical anatomy and characteristics of hemodynamic support. In addition, recent advances in the neurophysiologic assessment of the descending motor pathways and their application to perioperative monitoring are discussed.

Preoperative prediction of spinal cord ischemia after thoracic endovascular aortic repair

OBJECTIVE

Spinal cord ischemia (SCI) is a devastating but potentially preventable complication of thoracic endovascular aortic repair (TEVAR). The purpose of this analysis was to determine what factors predict SCI after TEVAR.

METHODS

All TEVAR procedures at a single institution were reviewed for patient characteristics, prior aortic repair history, aortic centerline of flow analysis, and procedural characteristics. SCI was defined as any lower extremity neurologic deficit that was not attributable to an intracranial process or peripheral neuropathy. Forty-three patient and procedural variables were evaluated individually for association with SCI. Those with the strongest relationships to SCI (P < .1) were included in a multivariable logistic regression model, and a stepwise variable elimination algorithm was bootstrapped to derive a best subset of predictors from this model.

RESULTS

From 2002 to 2013, 741 patients underwent TEVAR for various indications, and 68 (9.2%) developed SCI (permanent: n = 38; 5.1%). Because of the lack of adequate imaging for centerline analysis, 586 patients (any SCI, n = 43; 7.4%) were subsequently analyzed. Patients experiencing SCI after TEVAR were older (SCI, 72 ± 11 years; no SCI, 65 ± 15 years; P < .0001) and had significantly higher rates of multiple cardiovascular risk factors. The stepwise selection procedure identified five variables as the most important predictors of SCI: age (odds ratio [OR] multiplies by 1.3 per 10 years; 95% confidence interval [CI], 0.9-1.8, P = .06), aortic coverage length (OR multiplies by 1.3 per 5 cm; CI, 1.1-1.6; P = .002), chronic obstructive pulmonary disease (OR, 1.9; CI, 0.9-4.1; P = .1), chronic renal insufficiency (creatinine concentration ≥ 1.6 mg/dL; OR, 1.9; CI, 0.8-4.2; P = .1), and hypertension (defined as chart history or medication; OR, 6.4; CI, 2.6-18; P < .0001). A logistic regression model with just these five covariates had excellent discrimination (area under the receiver operating characteristic curve = .83) and calibration (χ(2) = 9.8; P = .28).

CONCLUSIONS

This analysis generated a simple model that reliably predicts SCI after TEVAR. This clinical tool can assist decision-making about when to proceed with TEVAR, guide discussions about intervention risk, and help determine when maneuvers to mitigate SCI risk should be implemented.

Vascular diseases of the spinal cord

Vascular disease affecting the spinal can cause substantial neurologic morbidity. Several vascular spinal cord ailments present as neurologic emergencies, and should thus be recognizable to the practicing neurologist. We review the epidemiology, presentation, management strategies, and prognosis of various pathologies, including infarction, dural arteriovenous fistula, arteriovenous malformation, cavernous malformation, compressive epidural hematoma, vasculitis, and genetic abnormalities.

Delayed onset of anterior spinal artery syndrome after repair of aortic coarctation

STUDY DESIGN

A case report.

OBJECTIVE

We report a case of delayed anterior spinal artery syndrome after repair of aortic coarctation in which the symptoms did not appear until 6 months after surgery.

SUMMARY OF BACKGROUND DATA

Residual dilatation of the anterior spinal artery after surgery can mimic a dilated intraspinal vein, which could lead to the erroneous diagnosis of spinal arteriovenous malformation as the cause for anterior spinal artery syndrome.

METHODS

A 40-year-old man with a history of hypertension underwent surgical bypass of the left subclavian artery to descending thoracic aorta to treat coarctation of the thoracic aorta and had an uncomplicated postoperative course. Six months later, he developed numbness and weakness in his hands. Magnetic resonance image showed abnormal signal within the cervicothoracic spinal cord and prominent flow voids within the ventral spinal canal. Spinal digital subtraction angiography revealed slow flow in a dilated intraspinal vessel. Given the history of aortic coarctation repair, the possibility that this represented a residually dilated anterior spinal artery rather than an arteriovenous malformation was considered and confirmed on magnetic resonance imaging.

RESULTS

In our patient, institution of an anticoagulation medication regime resulted in rapid improvement of neurological symptoms, underscoring the importance of the awareness of this phenomenon.

CONCLUSION

Delayed anterior spinal artery syndrome after aortic coarctation repair because of anterior spinal artery thrombosis can manifest even 6 months postoperatively. Careful analysis of pre- and postoperative cross-sectional imaging should provide the correct diagnosis. Spinal digital subtraction angiography is probably unnecessary and must be interpreted with caution.

Subacute anterior spinal cord ischemia with lower limb monoplegia: a clinical dilemma and challenging scenario

A 70-year-old woman presented with crescendo right lower limb monoplegia. Magnetic resonance imaging depicted anterior spinal artery syndrome with an 8.5 cm Crawford type II thoracoabdominal aortic aneurysm (TAAA). A staged hybrid procedure was performed, following which she had total exclusion of her TAAA and full resolution of her monoplegia. Clinical presentations of TAAAs can be diverse and require detailed clinical knowledge and lateral thinking to unearth unorthodox presentations. This erratic presentation of a TAAA with anterior spinal artery syndrome outlines particular challenges with management and portrays the need for tailored utilization of contemporary techniques to deal with the growing complexity of TAAAs.

The collateral network concept: a reassessment of the anatomy of spinal cord perfusion

OBJECTIVE

Prevention of paraplegia after repair of thoracoabdominal aortic aneurysm requires understanding the anatomy and physiology of the spinal cord blood supply. Recent laboratory studies and clinical observations suggest that a robust collateral network must exist to explain preservation of spinal cord perfusion when segmental vessels are interrupted. An anatomic study was undertaken.

METHODS

Twelve juvenile Yorkshire pigs underwent aortic cannulation and infusion of a low-viscosity acrylic resin at physiologic pressures. After curing of the resin and digestion of all organic tissue, the anatomy of the blood supply to the spinal cord was studied grossly and with light and electron microscopy.

RESULTS

All vascular structures at least 8 μm in diameter were preserved. Thoracic and lumbar segmental arteries give rise not only to the anterior spinal artery but to an extensive paraspinous network feeding the erector spinae, iliopsoas, and associated muscles. The anterior spinal artery, mean diameter 134 ± 20 μm, is connected at multiple points to repetitive circular epidural arteries with mean diameters of 150 ± 26 μm. The capacity of the paraspinous muscular network is 25-fold the capacity of the circular epidural arterial network and anterior spinal artery combined. Extensive arterial collateralization is apparent between the intraspinal and paraspinous networks, and within each network. Only 75% of all segmental arteries provide direct anterior spinal artery-supplying branches.

CONCLUSIONS

The anterior spinal artery is only one component of an extensive paraspinous and intraspinal collateral vascular network. This network provides an anatomic explanation of the physiological resiliency of spinal cord perfusion when segmental arteries are sacrificed during thoracoabdominal aortic aneurysm repair.

Penetrating wounds of great vessels

Thirty-six patients with penetrating wounds of the great vessels treated at Grady Memorial Hospital during a 7-year period were reviewed. In more than 50% of the cases, diagnosis of the injury was made at the time of emergency thoracotomy for massive bleeding. In the remaining patients the diagnosis was suspected: 1) when the pulse distal to the vascular injury was absent or weak; 2) when the patient had symptoms and signs of impaired central nervous system perfusion; 3) when the missile had traversed the mediastinum and there was roentgenographic evidence of widening of the mediastinal shadow; or, 4) when a new murmur appeared. In all suspected cases with great vessel injury, the diagnosis was confirmed arteriographically. Arteriography in such patients should be performed to define the type and site of vascular injury so that its repair can be properly planned. Twenty-nine patients recovered from their injury, 6 succumbed as a result of it and 1 required midforearm amputation following repair of a subclavian artery and vein injury. Most of these patients underwent autotransfusion which greatly contributed to their successful outcome. Local temporary shunt was used for protection of the spinal cord and/or brain when impairment of their perfusion was required for the repair of the vascular wounds.

Unilateral lower limb paralysis after aortobifemoral bypass graft for ruptured abdominal aortic aneurysm: a case report

An 81-year-old man underwent an aortobifemoral bypass graft because of a ruptured abdominal aortic aneurysm. His postoperative recovery was complicated by unilateral lower limb paralysis caused by perioperative ischemia of the lumbosacral plexus. Ischemic lumbosacral plexopathy is an uncommon complication after infrarenal aortic surgery with serious morbidity. Despite a good surgical technique and knowledge of the vascularization of the spinal cord, its occurrence remains unpredictable.

Paraplegia following the emergency surgical repair of a nonruptured symptomatic abdominal aortic aneurysm: report of a case

This report presents an extremely rare case of paraplegia following emergency surgery for a nonruptured symptomatic abdominal aortic aneurysm. A 62-year-old man underwent an emergency surgical repair for a symptomatic nonruptured infrarenal abdominal aortic aneurysm. On postoperative day 2 paraplegia following spinal cord ischemia occurred at the T8 level. The site of the ischemia was situated too high for clamping to have caused this condition, unless the patient had a congenital anomaly in the blood supply to the spinal cord or it had been caused by the previously occluded great radicular artery, which was maintained by the collateral blood supply from the iliac circulation.

A quantitative assessment of the impact of intercostal artery reimplantation on paralysis risk in thoracoabdominal aortic aneurysm repair

OBJECTIVES

We previously demonstrated an 80% reduction in paraplegia risk using hypothermia, naloxone, steroids, spinal fluid drainage, intercostal ligation, and optimizing hemodynamic parameters. This report demonstrates that intercostal revascularization for the last 3 years further reduced our paraplegia risk index by 75%.

METHODS

We evaluated 655 patients who had thoracic or thoracoabdominal aneurysm repair for factors that affected paraplegia risk including aneurysm extent, acuity, cardiac function, blood pressure mean arterial pressure, and spinal fluid drainage with naloxone (SFDN). Eighteen patients died during or shortly after surgery leaving 637 patients for analysis of paralysis. We evaluated the effect of intercostal reimplantation (IRP) using a highly accurate (r(2) > 0.88) paraplegia risk index we developed and published previously.

RESULTS

Fifty-eight percent of patients were male with a mean age of 67. Thirty-three percent were acute with rupture, acute dissection, mycotic aortitis, and trauma. Eighty (12%) had dissections. Thirty-five patients had paraplegia or paraparesis (5.4%). Significant factors by univariate analysis (P < 0.05) were Crawford type 2, acuity, SFDN, cardiac index after unclamping, mean arterial pressure during crossclamping, and IRP. In multivariate modeling, aneurysm extent, SFDN, acuity, and IRP remained significant (P < 0.02). The paraplegia risk index declined from 0.20 to 0.05 (P < 0.03).

CONCLUSIONS

The incidence of paralysis after TAAA repair decreased from 4.83% to 0.88% and paralysis risk index decreased from 0.26 to 0.05 when intercostal artery reimplantation was added to neuroprotective strategies that had already substantially reduced paralysis risk. These findings suggest that factors that affect collateral blood flow and metabolism account for approximately 80% of paraplegia risk and intercostal blood flow accounts for 20% of risk. This suggests a limit to paraplegia risk reduction in thoracoabdominal endograft patients. Early results in this emerging field support this prediction of high paraplegia risk with thoracoabdominal branched endografts with extensive aortic coverage.

Paraplegia with lumbar artery compression by the diaphragmatic crus

The authors report three cases of transient and recurrent paraplegia due to compression of the second right lumbar artery by the diaphragmatic crus. Circumstances of appearance are suggestive when paraplegia occurs in dorsolumbar hyperlordosis and low cardiac output is an associated hemodynamic risk factor. Selective medullary arteriography is indispensable for diagnosis and can demonstrate three signs: an anterior spinal dorsolumbar artery (artery of Adamkiewicz) that does not descend to the conus medullaris; posterior spinal arteries arising from the second lumbar arteries that vascularize the conus medullaris; existence of a tight stenosis on the second right lumbar artery that is aggravated during dynamic maneuvers. Section of the right diaphragmatic crus and release of the second right lumbar artery from the aorta to the fibrous arcade of the psoas permits definitive cure of symptoms.

Overview of Great Vessel Trauma

Traumatic injury to the aorta and the brachiocephalic branches are potentially lethal injuries. Specialized preoperative imaging and medical management can lead to better outcomes in this group of patients. In addition, improved surgical techniques for spinal cord protection have led to decreased morbidity in surgical candidates. TEVAR remains a promising technique; however, long-term data currently are not available.

Tetraplegia after elective abdominal aortic aneurysm repair

Spinal cord ischemia after elective infrarenal aortic aneurysm repair is extremely rare, and documented cases that are described are of paraplegia. This case of tetraplegia occurred in a 64-year-old man with disabling claudication after an aortobifemoral graft repair for occlusive disease associated with a 5-cm infrarenal aneurysm. Magnetic resonance imaging supported lower cervical spinal cord ischemia, an unusual area for ischemia during aortic clamping since this area is usually most resistant. Because the lower thoracic and upper lumbar region, typically T8, is more susceptible to ischemia due to the variable collateral spinal cord circulation, the level of clamping was unlikely to be responsible. Other causes are considered. It was likely to be multifactorial and illustrates the need for great attention to detail in perioperative management and patient consent.

Transcranial motor-evoked potentials monitoring can detect spinal cord ischemia more rapidly than spinal cord-evoked potentials monitoring during aortic occlusion in rats

In this study, we evaluated the efficacy of transcranial motor-evoked potentials (tc-MEPs), compared with segmental spinal cord-evoked potentials (SCEPs), for detecting spinal cord ischemia (SCI) and assessed the relationship between neurological outcome and tc-MEPs or SCEPs in the rat aortic occlusion model. In the rats, SCI was induced by aortic occlusion for 10 min with a balloon catheter. At first, tc-MEPs (Group A: n = 6) or segmental SCEPs (Group B: n = 6) was recorded during SCI. Second, in using the quantal bioassay for the relationship between an interval of aortic occlusion and the probability of positive response in tc-MEPs or segmental SCEPs, the P50(MEP) and P50(SCEP) which represent the interval of aortic occlusion associated with 50% probability of assessment of ischemic spinal cord dysfunction by tc-MEP and SCEP were analyzed. The amplitude of tc-MEPs decreased significantly at 30 s and disappeared completely at 2 min after aortic occlusion. In Group B, it took about 6 min after aortic occlusion to diminish SCEP signal amplitude by approximately 50%. P50(MEP) obtained in the quantal analysis was 0.3 +/- 0.1 min. P50(SCEP) was calculated as 6.2 +/- 0.5 min that was significantly (P < 0.01) longer than P50(MEP). Our data indicated that tc-MEP monitoring could detect the onset of SCI so rapidly in comparison with segmental SCEP monitoring, which could provide therapeutic windows in a surgical approach that includes spinal cord protection.

Myogenic transcranial motor evoked potentials monitoring cannot always predict neurologic outcome after spinal cord ischemia in rats

OBJECTIVES

A day after undergoing an operation of the thoracic aorta, a patient showed signs of spastic paraplegia, but on myogenic transcranial motor evoked potential monitoring, the myogenic transcranial motor evoked potentials recorded from the left anterior tibial muscle appeared normal. We sought to confirm these observations by using a rat spinal ischemia model to define the possibility of false-negative results in myogenic transcranial motor evoked potential monitoring by motor function behavior and spinal histopathology.

METHODS

Spinal ischemia was induced for 6 minutes (group A, n = 6) or 10 minutes (group B, n = 6) with an intra-aortic balloon. After ischemia, motor function was assessed periodically by using the motor deficit index (0, complete recovery; 6, complete paraplegia). Myogenic transcranial motor evoked potentials were recorded from the right soleus muscle before ischemia, 2 and 6 minutes after the start of spinal ischemia, and at 30 minutes, 24 hours, and 72 hours of reperfusion.

RESULTS

All group A rats showed normal motor function at 72 hours of reperfusion, whereas all group B rats displayed complete spastic paraplegia (motor deficit index = 6) at 72 hours of reperfusion. However, transcranial motor evoked potential was preserved in both group B and group A. Histopathologic analysis in group B revealed the presence of extensive necrotic changes of the gray matter distributed between laminae V through VII in the L3 to L5 segments but normal appearance of alpha motor neurons.

CONCLUSION

According to our data, in using myogenic transcranial motor evoked potential monitoring during thoracic or thoracoabdominal aneurysm repair, we should be aware that transcranial motor evoked potentials cannot always be used to predict neurologic outcome after the operation.

Upper and lower spinal cord blood supply: the continuity of the anterior spinal artery and the relevance of the lumbar arteries

OBJECTIVE

Thoracic and thoracoabdominal aortic repair are still complicated by spinal cord ischemia and paraplegia. The aim of the present article is to present the results of an anatomical study conducted by means of both postmortem injection of the vertebral artery and perfusion of the abdominal aorta.

METHODS

The spinal cord blood supply was investigated in 51 Caucasian cadavers: in 40 cases a methylene blue solution was hand-injected into the vertebral artery, whereas in the remaining 11 cases the abdominal aorta was perfused with a methylene blue solution by means of a roller pump. The level and side of the arteria radicularis magna and the continuity of the anterior spinal artery were recorded.

RESULTS

The anterior spinal artery was a continuous vessel without interruptions along the spinal cord in all 51 cases. The arteria radicularis magna level was variable, ranging from T9 to L5. The arteria radicularis magna arose from a lumbar artery in 36 cases (70.5%) and it was left-sided in 32 cases (62.7%).

CONCLUSIONS

The anterior spinal artery constitutes an uninterrupted pathway between the vertebral arteries, the arteria radicularis magna, and the posterior intercostal and lumbar arteries. Moreover, the arteria radicularis magna arises from a lumbar artery in most of cases. Therefore, the sacrifice of the intercostal arteries during a thoracic aorta repair could be justified, at least from an anatomical standpoint. However, if an extended thoracoabdominal aortic repair is planned, it may be prudent to preserve the blood flow from the lumbar arteries.

Spinal cord infarction caused by cardiac tamponade

This article describes a 16-yr-old male patient who went into shock and cardiac arrest 2 wk after surgical repair of an atrial septal defect. Cardiac tamponade was diagnosed and promptly treated, and his hemodynamic status stabilized 4 hr after the initial presentation of shock; however, paraplegia was found when the patient regained consciousness. Physicians should be alert to a possible diagnosis of spinal cord infarction in patients with complications of cardiovascular surgery, particularly when a new onset of neurologic symptoms or signs occurs.

Coarctation of the aorta

Controversy still exists in the literature regarding definitive therapy for repair of coarctation of the aorta. Major factors involve not only the timing of repair, but also the method of repair, whether surgical or by percutaneous transluminal balloon dilatation. Results and complications of coarctation repair using various methods of classification present a diversity of results. This report will focus on these issues and attempt to dispel the statement that either one method or the other is the "choice method" of repair for any and all types of coarctation. Also presented is a proposed classification we believe will assist in clarifying the choice of therapy and perhaps improve not only the reporting of results, but also the results themselves. Methods of repair are discussed to provide the surgeon with a complete armamentarium of operations that the surgeon would tailor to the individual anatomicopathological patterns of the patient who presents at the time of surgery. Copyright 2000 by W.B. Saunders Company

Selective perfusion of segmental arteries in patients undergoing thoracoabdominal aortic surgery

BACKGROUND

Reattachment of segmental arteries is one method used to prevent paraplegia associated with thoracoabdominal aortic repair. Nevertheless, even when important segmental arteries are reattached, ischemia causing spinal injury may occur during anastomosis.

METHODS

In 27 patients undergoing thoracoabdominal aortic repair, we attempted to perfuse the segmental arteries to be reattached with catheters connected to the distal bypass circuit. To identify perioperative risk factors for spinal ischemia, we examined changes in spinal somatosensory evoked potentials.

RESULTS

A median value of four segmental arteries were perfused in 20 (74%) of the 27 patients. Changes in somatosensory evoked potential indicative of spinal ischemia were observed in 13 patients (48%). The only risk factor associated with changes in evoked potentials revealed by a multivariate analysis was prolonged aortic cross-clamp time (> 120 minutes). Of the 2 patients who suffered paraplegia, one had the longest clamp time and the other showed spinal cord necrosis due to embolic shower.

CONCLUSIONS

Despite selective perfusion of segmental arteries, spinal ischemia associated with aortic cross-clamping may occur when clamping is prolonged over 120 minutes. Most of the changes appear to be reversible, however.

Indications and operative techniques for combined aortoesophageal resection

Combined aortoesophageal resection was performed in 8 patients, including 7 with esophageal carcinoma and 1 with aortoesophageal fistula. Aortic resection procedures included segmental resection with permanent aorto-aortic bypass (1 case), segmental resection with graft interposition (1 case), semicircumferential resection with patch aortoplasty (3 cases), wedge resection with lateral aortorrhaphy (1 case), and resection of adventitia (2 cases). Protective methods during aortic cross-clamping included one aorto-aortic permanent bypass, one subclavian-aortic bypass, and three axillo-femoral bypass. Postoperative complications include mediastinal abscess, paresis, arrythmia, and pneumonia. Five patients with esophageal carcinoma died within 6 postoperative months. In 4 of these 5 nonsurvivors, metastasis to distant organs including the liver, bone and peritoneal cavity were found at the time of death or autopsy. Those early recurrence cases were characterized by skip lesions and extensive lymph node metastasis with extranodal invasion. The clinical benefit of aortoesophageal resection will be attained by careful preoperative evaluation for case selection and a sufficient protective method for aortic cross-clamping.