Acute Type B Aortic Dissection Complicated With Spinal Cord Ischemia and Paraplegia Treated With Endovascular Scissor Technique.

Spinal cord ischemia leading to paraplegia is a rare, life-limiting complication of acute type B aortic dissection. We report a case of spinal cord ischemia occurred in a young woman treated with endovascular scissor technique in urgent setting. The patient had an uneventful post-procedural course. After 4 months, computed tomography angiography confirmed false lumen reperfusion and major symptoms were regressed. In selected cases, this procedure is a tool to improve false lumen perfusion in type B dissections, and demonstrated to be helpful in our case of spinal cord ischaemia.

Left Subclavian Artery Coverage is Not Associated with Neurological Deficits in Trauma Patients Undergoing Thoracic Endovascular Repair.

BACKGROUND: Endovascular repair of the thoracic aorta (TEVAR) outcomes have been studied with an interest in complications related to left subclavian artery (LSA) coverage in patients with atherosclerotic pathologies; however, specific data on the management of the LSA in a trauma population are lacking. The objective of this study is to evaluate outcomes following TEVAR for traumatic aortic injury based on LSA coverage. METHODS: The Vascular Quality Initiative thoracic endovascular aortic repair module (2010-2017) was analyzed. Patients were included if they had a traumatic aortic injury requiring TEVAR. Patients were placed in 2 groups based on coverage of the LSA. Patients were propensity score matched and the primary outcomes were cerebrovascular symptoms and spinal cord ischemia. Additional clinical and resource utilization outcomes were analyzed. RESULTS: Four hundred and fifty one patients were included in the analysis. There were 268 patients in the LSA not-covered group and 183 patients in the LSA covered group. The mean aortic injury grade was 2.88 ± 0.056 vs. 2.88 ± 0.049 in the covered versus not-covered group (P = 0.957). Glasgow coma scale and injury severity score were not different between the groups. There was no difference between groups for cerebrovascular symptoms or spinal cord ischemia, 1.4% vs. 2.8%, P = 0.684 and 0% vs. 2.1%, P = 0.247, after propensity score matching. Significant differences in access site complications and resource utilization were identified between groups. CONCLUSIONS: This is the largest series to evaluate complications based on LSA coverage following TEVAR in trauma patients. Our data demonstrate that coverage of the LSA during TEVAR following blunt trauma is associated with no difference in central nervous system outcomes. As such, LSA revascularization strategies, while possible, are not directly supported by these data and should be individualized based on each patient's specific clinical scenario.

Ischemic Complications Following Thoracic Endovascular Aortic Repair with and Without Revascularization of Left Subclavian Artery: A Systematic Review and Meta-Analysis.

BACKGROUND: Thoracic Endovascular Aortic Repair has been widely performed to treat various thoracic aortic pathologies. However, stent-graft placement in the thoracic aorta may result in left subclavian artery coverage, potentially leading to ischemic complications. The role of the left subclavian artery revascularization procedure to prevent ischemic complications remains controversial. Therefore, we conducted a systematic review and meta-analysis to identify ischemic outcomes in patients who underwent thoracic Endovascular Aortic Repair with or without left subclavian artery revascularization. METHODS: A systematic search through electronic databases, including PubMed, Ovid Medline, and Cochrane, was conducted to identify relevant studies. The outcome parameters were left arm ischemia, stroke, and spinal cord ischemia. Risk ratio (RR) and Confidence Interval (CI) of 95% were measured and reported. RESULTS: A total of 11,386 patients were identified from 22 studies. Patients who underwent left subclavian artery revascularization had lower risk of left arm ischemia (RR 0.25, 95% CI 0.09-0.68; P = 0.0006; I2 = 71%), lower risk of stroke (RR 0.52, 95% CI 0.30-0.88; P = 0.02; I2 = 70%), and lower risk of spinal cord ischemia (odds ratio OR 0.72, 95% CI 0.55-0.95; P = 0.02; I2 = 0%) between the 2 groups. CONCLUSIONS: Revascularization procedure in patients with left subclavian artery coverage during thoracic Endovascular Aortic Repair is associated with a lower risk of left arm ischemia, stroke, and spinal cord ischemia. Left subclavian artery revascularization should be performed in anatomically high-risk patients. High-quality studies are needed to validate the outcomes.

Clinically suspected fibrocartilaginous embolism: a case report and literature review.

Spinal cord infarction (SCI) occurs rarely and is characterized by abrupt onset of neck or back pain and neurologic deterioration. Fibrocartilaginous embolism (FCE) of the spinal cord is a rare but possible cause of acutely progressive spinal cord symptoms. Here, we report the case of an older woman who developed acute paraplegia with SCI on the 10th day after thoracic spine surgery. Although definitive FCE diagnosis can be confirmed only histologically, the characteristic clinical and radiological features were highly suggestive of FCE. Furthermore, 40 clinically suspected cases of FCE are reviewed.

Perioperative Spinal Cord Ischemia After Cardiac Surgery Not Involving the Aorta: A Review of the Literature.

Spinal cord ischemia (SCI) associated with aortic surgery is well-described; however, SCI after cardiac surgery not involving the aorta is an unusual and underappreciated phenomenon. The authors reviewed the literature and found 54 case reports of perioperative spinal cord ischemia in nonaortic surgery. The severity of its implications is evidenced by the fact that 14 patients died, 22 had no recovery, and seven had only partial recovery. Various types of cardiac surgery have reported this complication including coronary artery bypass grafting (CABG), off-pump CABG, valve surgeries, combination valve and CABG surgeries, and transcatheter aortic valve procedures. Patient comorbidities, such as high blood pressure, hypercholesterolemia, diabetes, and peripheral vascular disease, also may play a role in the development of this adverse outcome. The authors review the literature to define further possible mechanisms, surgical techniques, and patient factors that could contribute to the risk of perioperative SCI after cardiac surgery.

Incidence of spinal cord ischemia according to the patency of reimplanted segmental arteries during thoracoabdominal aortic replacement.

BACKGROUND: This study aimed to investigate the impact of segmental artery reimplantation and its patency on spinal cord ischemia (SCI) in thoracoabdominal aorta replacement. METHODS: For 193 patients who underwent early postoperative computed tomographic (CT) angiography after thoracoabdominal aorta replacement, the technique of segmental artery reimplantation, their patency, and postoperative SCI were retrospectively investigated. RESULTS: The early patency rate of reimplanted segmental artery was 83.3% (210 of 252), as 13 were taken down intraoperatively and 42 were not visualized in the postoperative CT angiography. The patency rate differed according to the reimplantation technique: 93.6% (131/140) for en bloc patch, 95.6% (43/45) for small individual patch, and 53.7% (36/67) for graft interposition. SCI occurred in 13 (6.3%) patients, 4 of whom (2.0%) remained paraplegic permanently. SCI was significantly more frequent (P=0.044) in the patients in whom segmental artery reimplantation was not successful (take-down or occlusion, 6/37=16.2%) than in those who had all segmental arteries sacrificed intentionally (2/64=3.1%) and those who showed patency of all reimplanted segmental arteries (5/92=5.4%). Especially, there was no permanent paraplegia in the last group. Failure of intended segmental artery reimplantation was a significant risk factor of postoperative SCI in logistic regression analysis (P=0.012; odds ratio 4.65, 95% confidence interval 1.41-15.36). CONCLUSIONS: During thoracoabdominal aorta replacement, attention should be paid to the segmental artery reimplantation technique, which affects the risk of occlusion or intraoperative take-down and thereby may have impact on postoperative SCI.

Spinal Cord Ischemia in the Setting of Acute Type B Aortic Dissection: Successful Rescue with Thoracic Endovascular Aortic Repair.

We report 2 cases of successful thoracic endovascular aortic repair (TEVAR) for acute type B aortic dissection (ABAD) complicated with spinal cord ischemia (SCI). Case 1. A 70-year-old gentleman found with an uncomplicated ABAD with false lumen occluded, developed SCI shortly after admission during the initial medical management. Cerebrospinal fluid drainage (CSFD) was initiated followed by emergent TEVAR. SCI improved, and the patient was discharged. Case 2. A 52-year-old gentleman developed uncomplicated ABAD with patent false lumen. 5 hours after admission, he developed SCI during the initial medical management. Emergent TEVAR was performed followed by CSFD, and the SCI improved before discharge. These cases prompted us to address prompt TEVAR for primary entry closure and true lumen dilatation with postoperative hypertensive management to relieve the dynamic obstruction of the segmental arteries responsible for the compromised spinal cord circulation in complicated ABAD.

Serum Neurofilament to Magnetic Resonance Imaging Lesion Area Ratio Differentiates Spinal Cord Infarction From Acute Myelitis.

BACKGROUND AND PURPOSE: The diagnosis of spontaneous spinal cord infarction (SCI) is limited by the lack of diagnostic biomarkers and MRI features that often overlap with those of other myelopathies, especially acute myelitis. We investigated whether the ratio between serum neurofilament light chain levels and MRI T2-lesion area (neurofilament light chain/area ratio-NAR) differentiates SCI from acute myelitis of similar severity. METHODS: We retrospectively identified Mayo Clinic patients (January 1, 2000-December 31, 2019) with (1) SCI, (2) AQP4 (aquaporin 4)-IgG or MOG (myelin oligodendrocyte glycoprotein)-IgG-associated myelitis at disease clinical presentation, or (3) idiopathic transverse myelitis from a previously identified population-based cohort of patients seronegative for AQP4-IgG and MOG-IgG. Serum neurofilament light chain levels (pg/mL) were assessed at the Verona University (SIMOA, Quanterix) in a blinded fashion on available stored samples obtained ≤3 months from myelopathy presentation. For each patient, the largest spinal cord lesion area (mm2) was manually outlined by 2 independent raters on sagittal T2-weighted MRI images, and the mean value was used to determine NAR (pg/[mL·mm2]). RESULTS: Forty-eight patients were included SCI, 20 (definite, 11; probable, 6; possible, 3); acute myelitis, 28 (AQP4-IgG-associated, 17; MOG-IgG-associated, 5; idiopathic transverse myelitis, 6). The median expanded disability status scale score (range) at myelopathy nadir were 7.75 (2-8.5) and 5.5 (2-8), respectively. Serum neurofilament light chain levels (median [range] pg/mL) in patients with SCI (188 [14.3-2793.4]) were significantly higher compared with patients with AQP4-IgG-associated myelitis (37 [0.8-6942.9]), MOG-IgG-associated myelitis (45.8 [4-283.8]), and idiopathic transverse myelitis (15.6 [0.9-217.8]); P=0.01. NAR showed the highest accuracy for identification of SCI versus acute myelitis with values ≥0.35 pg/(mL·mm2) yielding 86% specificity and 95% sensitivity (area under the curve=0.93). The positive and negative likelihood ratios were 6.67 and 0.06, respectively. NAR remained independently associated with SCI after adjusting for age, gender, immunotherapy before sampling, and days from myelopathy symptoms onset to sampling (P=0.0007). CONCLUSIONS: NAR is a novel and promising clinical biomarker for differentiation of SCI from acute myelitis.

Postoperative spinal cord ischaemia: magnetic resonance imaging and clinical features.

OBJECTIVES: Ischaemic spinal cord injury (SCI) is one of the most serious complications of aortic surgery. Ischaemic SCIs occur due to various aetiologies, and prediction of the risk is difficult. Magnetic resonance imaging (MRI) is useful to detect the details of spinal cord infarction. There are few studies about MRI for evaluating ischaemic SCI after cardiovascular surgery and aortic events. We report 9 cases of postoperative ischaemic SCI and analyse their MRI features. METHODS: T2-weighted MRI scans of 9 patients who developed ischaemic SCI due to cardiovascular surgery and aortic events between 2012 and 2017 were evaluated. RESULTS: In all patients, high-intensity areas were observed on T2-weighted magnetic resonance images. The site of infarction was the thoracic spinal cord level (9 cases) and additionally at the lumbar spinal cord level (5 cases). The area of infarction area was categorized based on the arterial territory: anterior spinal artery territory (3 cases), posterior spinal artery territory (2 cases), spinal sulcal artery territory (1 case) and artery of Adamkiewicz territory (3 cases). CONCLUSIONS: MRI revealed the infarction sites in all cases and the differences in the infarction patterns in each case. MRI could thus be useful for investigating the aetiology of ischaemic SCI following aortic surgeries and events.

Neurophysiologic Detection of Spinal Cord Ischemia During Anterior Vertebral Tethering.

STUDY DESIGN: Case report. OBJECTIVE: The aim of this study was to present how computed tomographic angiography (CTA) and intraoperative neurophysiologic monitoring (IONM) detect spinal cord ischemia during anterior spine surgery. These data directed expedient surgical and anesthetic interventions that restored IONM signals and prevented neurologic sequalæ. SUMMARY OF BACKGROUND DATA: Anterior vertebral tethering (AVT) is a fusionless surgical treatment of adolescent idiopathic scoliosis (AIS). METHODS: AVT was performed on a skeletally immature patient with AIS. Preoperative CTA detailed location of the dominant radicular artery (DRA). Transcranial motor (tcMEP) and somatosensory (SEP) evoked potentials were monitored during operation. RESULTS: There was significant decline in tcMEP, but not SEP, after compression of the DRA during cable tensioning of AVT. There was complete tcMEP recovery following release of instrumentation. CONCLUSION: This article identifies a rare but potentially catastrophic vascular hazard associated with anterior spine operation, including AVT. Sacrifice of multiple unilateral segmental vessels may overwhelm the capacity of collateral spinal cord perfusion to compensate for DRA blood supply. This vascular risk may be eliminated by identifying the DRA in order that it may be preserved during the procedure. LEVEL OF EVIDENCE: 5.

Spinal neurovascular complications with anterior thoracolumbar spine surgery: a systematic review and review of thoracolumbar vascular anatomy.

OBJECTIVE: Spinal cord infarction due to interruption of the spinal vascular supply during anterior thoracolumbar surgery is a rare but devastating complication. Here, the authors sought to summarize the data on this complication in terms of its incidence, risk factors, and operative considerations. They also sought to summarize the relevant spinal vascular anatomy. METHODS: They performed a systematic literature review of the PubMed, Scopus, and Embase databases to identify reports of spinal cord vascular injury related to anterior thoracolumbar spine procedures as well as operative adjuncts and considerations related to management of the segmental artery ligation during such anterior procedures. Titles and abstracts were screened, and studies meeting inclusion criteria were reviewed in full. RESULTS: Of 1200 articles identified on the initial screening, 16 met the inclusion criteria and consisted of 2 prospective cohort studies, 10 retrospective cohort studies, and 4 case reports. Four studies reported on the incidence of spinal cord ischemia with anterior thoracolumbar surgery, which ranged from 0% to 0.75%. Eight studies presented patient-level data for 13 cases of spinal cord ischemia after anterior thoracolumbar spine surgery. Proposed risk factors for vasculogenic spinal injury with anterior thoracolumbar surgery included hyperkyphosis, prior spinal deformity surgery, combined anterior-posterior procedures, left-sided approaches, operating on the concavity side of a scoliotic curve, and intra- or postoperative hypotension. In addition, eight studies analyzed operative considerations to reduce spinal cord ischemic complications in anterior thoracolumbar surgery, including intraoperative neuromonitoring and preoperative spinal angiography. CONCLUSIONS: While spinal cord infarction related to anterior thoracolumbar surgery is rare, it warrants proper consideration in the pre-, intra-, and postoperative periods. The spine surgeon must be aware of the relevant risk factors as well as the pre- and intraoperative adjuncts that can minimize these risks. Most importantly, an understanding of the relevant spinal vascular anatomy is critical to minimizing the risks associated with anterior thoracolumbar spine surgery.

Intravenous delivery of mesenchymal stem cells protects both white and gray matter in spinal cord ischemia.

Ischemic spinal cord injury (iSCI) is a devastating complication of aortic surgery, with few strategies for prevention. Intravenous infusion of mesenchymal stem cells (MSCs) for iSCI has been shown to provide functional improvement through protection of gray matter. The purpose of this study was to investigate additional mechanisms which may exert therapeutic efficacy in iSCI. Severe iSCI was created to occlude the descending aorta, which was cross-clamped 5 mm distal to the left subclavian artery for 16 min. One day after iSCI induction, iSCI rats were randomized into two groups: one received intravenous infusion of MSCs (MSC-group), the other received vehicle (no cells; vehicle-group). Locomotor function and in vivo MRI were recorded. H&E, Nissl and toluidine blue stainings, immunohistochemical analysis, diffusion tensor imaging (DTI), and the assessment of blood-spinal cord barrier (BSCB) stability were performed. MSC treated animals exhibited gradual improvement in hind-limb locomotor function during the 4-week study period; however the vehicle-treated group displayed persistent motor deficits. In the MSC-treated group we observed the protection of white and gray matter volume reduction of axonal and neuronal loss or degeneration and preservation of microvasculature including BSCB function. Intravenous infusion of MSCs may provide therapeutic efficacy to improve functional outcomes in a rat model of severe iSCI via protection of white and gray matter.

Multi-Site Optical Monitoring of Spinal Cord Ischemia during Spine Distraction.

Optimal surgical management of spine trauma will restore blood flow to the ischemic spinal cord. However, spine stabilization may also further exacerbate injury by inducing ischemia. Current electrophysiological technology is not capable of detecting acute changes in spinal cord blood flow or localizing ischemia. Further, alerts are delayed and unreliable. We developed an epidural optical device capable of directly measuring and immediately detecting changes in spinal cord blood flow using diffuse correlation spectroscopy (DCS). Herein we test the hypothesis that our device can continuously monitor blood flow during spine distraction. Additionally, we demonstrate the ability of our device to monitor multiple sites along the spinal cord and axially resolve changes in spinal cord blood flow. DCS-measured blood flow in the spinal cord was monitored at up to three spatial locations (cranial to, at, and caudal to the distraction site) during surgical distraction in a sheep model. Distraction was halted at 50% of baseline blood flow at the distraction site. We were able to monitor blood flow with DCS in multiple regions of the spinal cord simultaneously at ∼1 Hz. The distraction site had a greater decrement in flow than sites cranial to the injury (median -40 vs. -7%,). This pilot study demonstrated high temporal resolution and the capacity to axially resolve changes in spinal cord blood flow at and remote from the site of distraction. These early results suggest that this technology may assist in the surgical management of spine trauma and in corrective surgery of the spine.

A case report: white cord syndrome following anterior cervical discectomy and fusion: importance of prompt diagnosis and treatment.

BACKGROUND: Objective: White cord syndrome is extremely rare and search of the literature has revealed very few cases. Postoperative MR scan revealed hyperintense intrinsic cord signal changes within cord ischemia and edema. It is thought to be caused by reperfusion injury of the spinal cord. This is called white cord syndrome. This report is very rare case of 'White Cord Syndrome' with paraplegia after anterior cervical discectomy and fusion (ACDF). CASE PRESENTATION: A 49-year-old woman presented with neck pain lasting for several months and second and third finger radiating pain. Severe cervical herniated intervertebral disc findings could be identified at C6-7 level on C-spine MRI. ACDF C6-7 surgery was performed. Immediately after the operation, physical examination revealed paraplegia and emergency MRI was performed. On MR images, T2 high signal myelopathy suspected as reperfusion injury at C6-7 level, and emergency surgery was performed under diagnosis of white cord syndrome. After the emergency operation, the paraplegic problem was gradually resolved. Before discharge, motor power and sensory deficit of bilateral lower extremity were fully recovered. CONCLUSION: Surgeons should explain the possibility of white cord syndrome before cervical decompression surgery and should perform a neurological examination immediately after surgery. We recommend that the importance of early recognition and prompt treatment of white cord syndrome.

Occlusion of the Celiac Artery during Endovascular Thoracoabdominal Aortic Aneurysm Repair Is associated with Increased Perioperative Morbidity and Mortality.

BACKGROUND: Some studies suggest that celiac artery coverage during elective endovascular thoracoabdominal aortic aneurysm (TAAA) repair is safe given sufficient collateralization of visceral organ perfusion from the superior mesenteric artery. However, there is concern that celiac artery coverage may lead to increased risk of foregut or spinal cord ischemia with an attendant increased risk of mortality. We sought to investigate rates of bowel ischemia, spinal cord ischemia, and 30-day mortality associated with celiac artery coverage during TEVAR and complex EVAR. METHODS: The Society for Vascular Surgery Vascular Quality Initiative database was queried for TEVAR and complex EVAR cases from 2012 to 2018. Inclusion criteria included TAAA pathology and endograft extension to aortic zone 6. Patients with aortic rupture, trauma, prior thoracic aortic surgery, known preoperative occlusion of the left subclavian superior mesenteric, or celiac arteries were excluded. Cases with intraoperative celiac artery occlusion (CAO) were compared retrospectively to cases with celiac artery preservation (CAP). Primary outcomes included 30-day mortality and a composite end point of 30-day mortality, spinal cord ischemia (transient or permanent lower extremity neurologic deficit), and bowel ischemia (colonoscopic evidence of ischemia, bloody stools in a patient who dies prior to colonoscopy or laparotomy, or other documented clinical diagnosis). Univariable comparisons were performed using chi-squared tests and Student's t-tests, as appropriate. Multivariable logistic regression analyses were employed to identify independent predictors of outcome. RESULTS: There were 628 cases identified for inclusion in the study. Patients undergoing CAO (n = 44) were more likely to be female or to have higher rates of preoperative spinal drain use, American Society of Anesthesiologists score ≥3, low preop hemoglobin, and/or symptomatic presentation, but fewer mean number of aortic zones covered. CAO was associated with higher 30-day mortality (5 of 44, 11%) compared to CAP (23 of 584, 4%), P = 0.039. The composite end point occurred at a significantly greater proportion for those who had CAO (10 of 44, 23%) compared to CAP (53 of 584, 9%, P = 0.008), driven by higher rates of 30-day mortality and bowel ischemia (9% vs. 2%, P = 0.026). By multivariate analysis, CAO was predictive of 30-day mortality (odds ratio [OR] = 3.9, 95% confidence interval [CI] = 1.1-13.8, P = 0.04) and the composite endpoint (OR = 3.0, 95% CI = 1.1-8.5, P = 0.03). Increasing procedure time was also associated with 30-day mortality (OR = 1.4, 95% CI = 1.1-1.7, P < 0.001) and the composite end point (OR = 1.4, 95% CI = 1.1-1.6, P < 0.001). CONCLUSIONS: For those treated for TAAAs, CAO was independently predictive of increased 30-day mortality and a composite end point of perioperative mortality, spinal cord ischemia, and bowel ischemia. When treating patients with extensive aortic aneurysmal disease, physicians should attempt to preserve the celiac artery, by revascularization or avoiding ostium coverage, whenever feasible.

Spinal Cord Ischemia Rescue after Hybrid Total Arch Repair with Frozen Elephant Trunk: A Case Report.

Frozen elephant trunk repair is a technique described to simplify total arch repair for Stanford type A aortic dissection. Spinal cord ischemia is a devastating complication after frozen elephant trunk repair. In this report, we describe a case of spinal cord ischemia resulting in paralysis after frozen elephant trunk repair. Our spinal cord ischemia protocol was implemented and rescued patients from paraplegia. We report a dedicated spinal cord ischemia protocol that can rescue patients from paraplegia after hybrid arch repair with frozen elephant trunk.

Association between false lumen segmental arteries and spinal cord ischemia in type A acute aortic dissection.

BACKGROUND: Spinal cord ischemia (SCI) and paraplegia are complications of surgery for type A acute aortic dissection (TAAAD). Since the segmental arteries play a key role in SCI, this study evaluated the association between SCI and false lumen segmental arteries (FLSAs: segmental arteries originating from the false lumen). METHODS: The study included 101 consecutive TAAAD patients (mean age, 66±13; range, 34-89 years) who underwent surgery from January 2011 to April 2017. The diagnosis of TAAAD and the number of FSLAs were determined by preoperative computed tomography (CT). Patients were divided into two groups according to the number of FLSAs at the Th9-L2 level: Group A (N.=13), ≥8 FLSAs; and group B (N.=88), ≤7 FLSAs. Preoperative, perioperative, and postoperative findings were compared between the groups, and risk factors for SCI were evaluated. RESULTS: The frequency of preoperative paralysis was significantly higher in Group A than Group B (P=.0070). The overall incidence of postoperative SCI was 8% (8/101) and significantly higher in Group A than Group B (5/13 [45%] vs. 3/88 (4%), P<0.0001). Hospital mortality was 8% (8/101) and significantly higher in Group A than Group B (3/13 [23%] vs. 5/88 [6%], P=.0302). Multivariate analysis showed that the independent risk factors for SCI were ≥8 FLSAs at Th9-L2 (odds ratio [OR], 20.4; 95% confidence interval [95% CI], 3.34-124.9, P=0.0011) and diabetes mellitus (OR, 22.3; 95% CI, 1.69-294.5; P=0.0184). CONCLUSIONS: In patients who underwent surgery for TAAAD, ≥8 FLSAs at the Th9-L2 levels on preoperative CT was a risk factor for SCI.