Spinal cord complications after thoracic aortic surgery: long-term survival and functional status varies with deficit severity

Efficacy and Safety of Endovascular Fenestrated and Branched Grafts Versus Open Surgery in Thoracoabdominal Aortic Aneurysm Repair: An Updated Systematic Review, Meta-analysis, and Meta-regression

OBJECTIVE

To provide an updated systematic review and meta-analysis with meta-regression of efficacy and safety of fenestrated/branched endovascular repair of thoracoabdominal aortic aneurysms (TAAAs) compared with open repair.

BACKGROUND

Endovascular repair of TAAAs may be a promising alternative to open surgery by reducing invasiveness and expanding the eligible population, but evidence remains limited.

METHODS

We applied "Prepared Items for Systematic Reviews and Meta-analysis" guidelines to retrieve, quantitatively pool, and critically evaluate the efficacy and safety (including 30-day mortality, reintervention, spinal cord injury [SCI], and renal injury) of both approaches. Original studies were retrieved from PubMed, Embase, and Cochrane Library until April 20, 2022, excluding papers reporting <10 patients. Pooled proportions and means were determined using a random-effect model. Heterogeneity between studies was evaluated with I2 statistics.

RESULTS

Sixty-four studies met the predefined inclusion criteria. Endovascular cohort patients were older and had higher rates of comorbidities. Endovascular repair was associated with similar proportions of mortality (0.07, 95% confidence intervals [CI]: 0.06-0.08) compared with open repair (0.09, 95% CI: 0.08-0.12; P = 0.22), higher proportions of reintervention (0.19, 95% CI: 0.13-0.26 vs 0.06, 95% CI: 0.04-0.10; P < 0.01), similar proportions of transient SCI (0.07, 95% CI: 0.05-0.09 vs 0.06, 95% CI: 0.05-0.08; P = 0.28), lower proportions of permanent SCI (0.04, 95% CI: 0.03-0.05 vs 0.06, 95% CI: 0.05-0.07; P < 0.01), and renal injury (0.08, 95% CI: 0.06-0.10 vs 0.13, 95% CI: 0.09-0.17; P = 0.02). Results were affected by high heterogeneity and potential publication bias.

CONCLUSIONS

Despite these limitations and the lack of randomized trials, this meta-analysis suggests that endovascular TAAA repair could be a safer alternative to the open approach.

Health Related Quality of Life Following Intervention for Thoracoabdominal Aortic Aneurysm: A Systematic Review and Narrative Synthesis

BACKGROUND

Thoracoabdominal aortic aneurysms (TAAA) pose significant risks of morbidity and mortality. Considering the evolving techniques for TAAA intervention and the growing interest in quality of life (QoL) outcomes for decision-making, we aimed to evaluate the impact of patient and perioperative characteristics on short-term, medium-term, and long-term postoperative QoL in TAAA repair patients.

METHODS

A systematic search was conducted in CINAHL, APA PsycINFO, EMBASE, Medline and Cochrane to identify primary research studies evaluating QoL post TAAA surgery, published in English or Swedish between January 01, 2012 and September 26, 2022. A narrative synthesis was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The quality of evidence was assessed using the Critical Appraisal Skills Program and Joanna Briggs Institute checklists.

RESULTS

Eight studies of low or moderate quality with 455 patients were included. Preoperative QoL in TAAA patients was lower compared to the general population. While there is an initial short-term improvement in postoperative QoL, patients fail to reach baseline levels even after 7 years, with physical activity and functioning domains being particularly affected. Experiencing postoperative complications, including paraplegia and cardiovascular events, negatively impacts postoperative QoL. Patients with uncomplicated postoperative status had improved QoL. Prolonged hospital stay negatively affects physical functioning.

CONCLUSIONS

Individuals with TAAA are likely to have lower baseline QoL compared to the general population. Following TAAA repair, postoperative QoL may remain lower than baseline levels, persisting over the long-term. Comorbidities, postoperative complications, and hospitalization duration appear to exert adverse effects on postoperative QoL.

Usefulness of Motor Evoked Potential Measurement and Analysis of Risk Factors for Spinal Cord Ischaemia from 300 Cases of Thoracic Endovascular Aortic Repair

OBJECTIVE

This study investigated the usefulness of motor evoked potentials (MEPs) for intra-operative monitoring to detect the risk of spinal cord ischaemia (SCI) during thoracic endovascular aortic repair (TEVAR). Risk factors for SCI in TEVAR were also analysed.

METHODS

Among 330 TEVARs performed from February 2009 to October 2018, 300 patients underwent intra-operative MEP monitoring. SCI risk groups were extracted based on MEP amplitude changes using a cutoff value of 50%. When the amplitude decreased to < 50% of the pre-operative value, intra-operative mean arterial pressure (MAP) was increased by about 20 mmHg using noradrenaline, whereas MAP was usually controlled to about 80 mmHg during surgery. Other efforts were also made to increase MEP amplitude by increasing cardiac output, correcting anaemia, and finishing the surgery promptly. Based on MEP amplitude data, SCI risk groups were extracted and risk factors for SCI in TEVAR were analysed.

RESULTS

A total of 283 non-SCI risk patients and 17 SCI risk patients by MEP monitoring were extracted; only 1.0% developed immediate paraplegia and none developed delayed paraplegia. Bivariable analysis showed significant differences in chronic kidney disease, haemodialysis, artery of Adamkiewicz closure, and stent graft (SG) covered length ≥ 8 vertebral bodies. Logistic regression analysis showed hyperlipidaemia (odds ratio [OR] 3.55, 95% confidence interval [CI] 1.08 - 11.67; p = .037), SG covered length ≥ 8 vertebral bodies (OR 1.35, 95% CI 1.02 - 1.78; p = .034), and haemodialysis (OR 27.78, 95% CI 6.02 - 128.22; p < .001) were the most influential risk factors for SCI in TEVAR.

CONCLUSION

MEPs might be a useful monitoring tool to predict SCI in TEVAR. In addition, hyperlipidaemia, SG covered length ≥ 8 vertebral bodies, and haemodialysis represent key risk factors for SCI during TEVAR.

EGFR-Activated JAK2/STAT3 Pathway Confers Neuroprotection in Spinal Cord Ischemia-Reperfusion Injury: Evidence from High-Throughput Sequencing and Experimental Models

This study aimed to investigate the molecular mechanisms underlying spinal cord ischemia-reperfusion (SCI/R) injury. Through RNA-Seq high-throughput sequencing and bioinformatics analysis, we found that EGFR was downregulated in the spinal cord of SCI/R mice and may function via mediating the JAK2/STAT3 signaling pathway. In vitro cell experiments indicated that overexpression of EGFR activated the JAK2/STAT3 signaling pathway and reduced neuronal apoptosis levels. In vivo animal experiments further confirmed this conclusion, suggesting that EGFR inhibits SCI/R-induced neuronal apoptosis by activating the JAK2/STAT3 signaling pathway, thereby improving SCI/R-induced spinal cord injury in mice. This study revealed the molecular mechanisms of SCI/R injury and provided new therapeutic strategies for treating neuronal apoptosis.

A slow-releasing donor of hydrogen sulfide inhibits neuronal cell death via anti-PANoptosis in rats with spinal cord ischemia‒reperfusion injury

BACKGROUND

Spinal cord ischemia‒reperfusion injury (SCIRI) can lead to paraplegia, which leads to permanent motor function loss. It is a disastrous complication of surgery and causes tremendous socioeconomic burden. However, effective treatments for SCIRI are still lacking. PANoptosis consists of three kinds of programmed cell death, pyroptosis, apoptosis, and necroptosis, and may contribute to ischemia‒reperfusion-induced neuron death. Previous studies have demonstrated that hydrogen sulfide (H2S) exerts a neuroprotective effect in many neurodegenerative diseases. However, whether H2S is anti-PANoptosis and neuroprotective in the progression of acute SCIRI remains unclear. Thus, in this study we aimed to explore the role of H2S in SCIRI and its underlying mechanisms.

METHODS

Measurements of lower limb function, neuronal activity, microglia/macrophage function histopathological examinations, and biochemical levels were performed to examine the efficacy of H2S and to further demonstrate the mechanism and treatment of SCIRI.

RESULTS

The results showed that GYY4137 (a slow-releasing H2S donor) treatment attenuated the loss of Nissl bodies after SCIRI and improved the BBB score. Additionally, the number of TUNEL-positive and cleaved caspase-3-positive cells was decreased, and the upregulation of expression of cleaved caspase-8, cleaved caspase-3, Bax, and Bad and downregulation of Bcl-2 expression were reversed after GYY4137 administration. Meanwhile, both the expression and activation of p-MLKL, p-RIP1, and p-RIP3, along with the number of PI-positive and RIP3-positive neurons, were decreased in GYY4137-treated rats. Furthermore, GYY4137 administration reduced the expression of NLRP3, cleaved caspase-1 and cleaved GSDMD, decreased the colocalization NeuN/NLRP3 and Iba1/interleukin-1β-expressing cells, and inhibited proinflammatory factors and microglia/macrophage polarization.

CONCLUSIONS

H2S ameliorated spinal cord neuron loss, prevented motor dysfunction after SCIRI, and exerted a neuroprotective effect via the inhibition of PANoptosis and overactivated microglia-mediated neuroinflammation in SCIRI.

Aortic Reoperation After Prior Acute Type A Aortic Dissection Repair: Don't Despair the Repair

BACKGROUND

There is paucity of data regarding reoperation after acute type A aortic dissection (ATAD) repair.

METHODS

From October 2006 to March 2022, 75 patients received 123 reoperations after ATAD (proximal, n = 17; distal, n = 103; and both, n = 3) utilizing redo sternotomy (RS, n = 68), left thoracotomy (LT, n = 44), and endovascular approach (TEVAR, n = 11). The axillary artery cannulation was utilized in 97.1% of the RS cases. A classic elephant trunk technique was used as a 2-staged procedure for distal pathology. Most LT repairs (95.5%) were completed above the celiac axis.

RESULTS

Index ATAD repairs were predominantly ascending/hemiarch repair (73.3%). The median duration from the index repair was 2.0 years. Most reoperations were elective procedures (82.1%). Hospital mortality was 2.4% (RS, 1.5%; LT, 4.5%; TEVAR, 0%), and the stroke rate was 1.6%. There was no spinal cord ischemia. The 5-year overall survival and freedom from aortic mortality or procedure were 85.2% ± 5.6% and 80.6% ± 6.1%, respectively. There were 7 distal reinterventions (prior TEVAR, n = 3; prior LT, n = 4). Two patients required LT repair after prior TEVAR and 3 patients received infrarenal aortic repair after prior LT repair. Computed tomography after completion of the distal repair (n = 45) showed an increase of distal aorta at each level as follows: celiac axis 1.2 mm/y; renal artery 1.0 mm/y; and terminal aorta 1.2 mm/y.

CONCLUSIONS

Reoperation after ATAD repair can be safely performed as an elective procedure at experienced centers. Staged distal interventions utilizing classic elephant trunk insertion and open repair above the celiac axis showed durable outcomes.

In-hospital cost-effectiveness analysis of open versus staged fenestrated/branched endovascular elective repair of thoracoabdominal aneurysms

OBJECTIVE

To compare costs and effectiveness of elective open (OR) versus fenestrated/branched endovascular (ER) repair of thoracoabdominal aneurysms (TAAA) in a high-volume center.

METHODS

This single-center retrospective observational study (PRO-ENDO TAAA Study, NCT05266781) was designed as part of a larger Health Technology Assessment analysis. All electively treated TAAAs between 2013 and 2021 were analyzed and propensity-matched. Endpoints were clinical success, major adverse events (MAE), hospital direct costs, and freedom from all causes and aneurysm-related mortality and reinterventions. Risk factors and outcomes were homogeneously classified according to the Society of Vascular Surgery reporting standards. Cost-effectiveness value (CEV) and Incremental Cost-Effectiveness Ratio (ICER) were calculated, considering the absence of MAEs as a measure of effectiveness.

RESULTS

Propensity matching identified 102 pairs of patients out of 789 TAAAs. Mortality, MAE, permanent spinal cord ischemia rates, respiratory complications, cardiac complications, and renal injury were higher for OR (13% vs 5%, p=.048; 60% vs 17%, p<.001; 10% vs 3%, p=.045; 91% vs 18%, p<.001; 16% vs 6%, p=.024; 27% vs 6%, p<.001; respectively). Access complication rate (6% vs 27%; p<.001) was higher in the ER group. Intensive Care Unit stay was longer (p<.001) for OR and ER patients were discharged home more frequently (3% vs 94%; p<.001). No differences in mid-term endpoints were observed at 2 years. Despite ER reducing all the hospital cost items (-42% to -88%, p<.001), the higher expenses (p<.001) of the endovascular devices increased the overall cost of ER by 80%. CEV for ER was favorable to OR (56 365 vs 64 903 €/patient) with an ICER of 48 409 € per MAE saved.

CONCLUSIONS

ER of TAAA reduces perioperative mortality and morbidity compared to OR, with no differences in reinterventions and survival rates at midterm follow-up. Despite the expenses for endovascular grafts, ER resulted more cost-effective in preventing MAEs.

Comparison of single- and multistage strategies during fenestrated-branched endovascular aortic repair of thoracoabdominal aortic aneurysms

OBJECTIVE

The aim of this study was to compare outcomes of single or multistage approach during fenestrated-branched endovascular aortic repair (FB-EVAR) of extensive thoracoabdominal aortic aneurysms (TAAAs).

METHODS

We reviewed the clinical data of consecutive patients treated by FB-EVAR for extent I to III TAAAs in 24 centers (2006-2021). All patients received a single brand manufactured patient-specific or off-the-shelf fenestrated-branched stent grafts. Staging strategies included proximal thoracic aortic repair, minimally invasive segmental artery coil embolization, temporary aneurysm sac perfusion and combinations of these techniques. Endpoints were analyzed for elective repair in patients who had a single- or multistage approach before and after propensity score adjustment for baseline differences, including the composite 30-day/in-hospital mortality and/or permanent paraplegia, major adverse event, patient survival, and freedom from aortic-related mortality.

RESULTS

A total of 1947 patients (65% male; mean age, 71 ± 8 years) underwent FB-EVAR of 155 extent I (10%), 729 extent II (46%), and 713 extent III TAAAs (44%). A single-stage approach was used in 939 patients (48%) and a multistage approach in 1008 patients (52%). A multistage approach was more frequently used in patients undergoing elective compared with non-elective repair (55% vs 35%; P < .001). Staging strategies were proximal thoracic aortic repair in 743 patients (74%), temporary aneurysm sac perfusion in 128 (13%), minimally invasive segmental artery coil embolization in 10 (1%), and combinations in 127 (12%). Among patients undergoing elective repair (n = 1597), the composite endpoint of 30-day/in-hospital mortality and/or permanent paraplegia rate occurred in 14% of single-stage and 6% of multistage approach patients (P < .001). After adjustment with a propensity score, multistage approach was associated with lower rates of 30-day/in-hospital mortality and/or permanent paraplegia (odds ratio, 0.466; 95% confidence interval, 0.271-0.801; P = .006) and higher patient survival at 1 year (86.9±1.3% vs 79.6±1.7%) and 3 years (72.7±2.1% vs 64.2±2.3%; adjusted hazard ratio, 0.714; 95% confidence interval, 0.528-0.966; P = .029), compared with a single stage approach.

CONCLUSION

Staging elective FB-EVAR of extent I to III TAAAs was associated with decreased risk of mortality and/or permanent paraplegia at 30 days or within hospital stay, and with higher patient survival at 1 and 3 years.

Endoplasmic Reticulum Stress Causing Apoptosis in a Mouse Model of an Ischemic Spinal Cord Injury

A spinal cord injury (SCI) is the devastating trauma associated with functional deterioration due to apoptosis. Most laboratory SCI models are generated by a direct impact on an animal's spinal cord; however, our model does not involve the direct impact on the spinal cord. Instead, we use a clamp compression to create an ischemia in the descending aortas of mice. Following the success of inducing an ischemic SCI (ISCI), we hypothesized that this model may show apoptosis via an endoplasmic reticulum (ER) stress pathway. This apoptosis by the ER stress pathway is enhanced by the inducible nitric oxide synthase (iNOS). The ER is used for the protein folding in the cell. When the protein folding capacity is overloaded, the condition is termed the ER stress and is characterized by the accumulation of misfolded proteins inside the ER lumen. The unfolded protein response (UPR) signaling pathways that deal with the ER stress response then become activated. This UPR activates the three signal pathways that are regulated by the inositol-requiring enzyme 1α (IRE1α), the activating transcription factor 6 (ATF6), and the protein kinase RNA-like ER kinase (PERK). IRE1α and PERK are associated with the expression of the apoptotic proteins. Apoptosis caused by an ISCI is assessed using the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) test. An ISCI also reduces synaptophysin and the neuronal nuclear protein (NeuN) in the spinal cord. In conclusion, an ISCI increases the ER stress proteins, resulting in apoptosis in neuronal cells in the spinal cord.

Cerebrospinal Fluid Drainage for Prevention of Spinal Cord Ischemia in Thoracic Endovascular Aortic Surgery-Pros and Cons

Thoracic endovascular aortic repair (TEVAR) carries a risk of spinal cord ischemia (SCI) which exerts a devastating impact on patient's quality of life and life expectancy. Although routine prophylactic cerebrospinal fluid (CSF) drainage is not unequivocally supported by current data, several studies have demonstrated favorable outcomes. Patients at high risk for SCI following TEVAR likely will benefit from prophylactic CSF drains. However, the intervention is not risk free, and thorough risk/benefit analysis should be individualized to each patient.

Effects of Lycopene Attenuating Injuries in Ischemia and Reperfusion

Tissue and organ ischemia can lead to cell trauma, tissue necrosis, irreversible damage, and death. While intended to reverse ischemia, reperfusion can further aggravate an ischemic injury (ischemia-reperfusion injury, I/R injury) through a range of pathologic processes. An I/R injury to one organ can also harm other organs, leading to systemic multiorgan failure. A type of carotenoid, lycopene, has been shown to treat and prevent many diseases (e.g., rheumatoid arthritis, cancer, diabetes, osteoporosis, male infertility, neurodegenerative diseases, and cardiovascular disease), making it a hot research topic in health care. Some recent researches have suggested that lycopene can evidently ameliorate ischemic and I/R injuries to many organs, but few clinical studies are available. Therefore, it is essential to review the effects of lycopene on ischemic and I/R injuries to different organs, which may help further research into its potential clinical applications.

Spinal Cord Ischemia After Thoracoabdominal Aortic Aneurysms Endovascular Repair: From the Italian Multicenter Fenestrated/Branched Endovascular Aneurysm Repair Registry

PURPOSE

The aim of this study is to report an Italian multicenter experience analyzing the incidence and the risk factors associated with spinal cord ischemia (SCI) in a large cohort of thoracoabdominal aortic aneurysms (TAAAs) treated by fenestrated-branched endovascular aneurysm repair (F-/B-EVAR).

MATERIALS AND METHODS

All consecutive patients undergoing F-/B-EVAR in 4 Italian university centers between 2008 and 2019 were prospectively recorded and retrospectively analyzed. Spinal cord ischemia, 30 day/in-hospital adverse events, and mortality were assessed as early outcomes. Risk factors for SCI were determined by multivariable analysis.

RESULTS

A total of 351 patients received F-/B-EVAR for a TAAA. Twenty-eight (8.0%) patients died within 30 postoperative days or during the hospitalization. Regarding SCI, 47 patients (13.4%) developed neurological symptoms related to spinal cord impaired perfusion. Among them, 17 (4.8%) had a major permanent impairment. The multivariable analysis identified that SCI was associated with Crawford extent I to III (odds ratio [OR]: 20.90, p=0.004, 95% confidence interval [CI]=2.69-162.57), and with endovascular procedures performed for ruptured TAAA (OR: 5.74, p=0.010, 95% CI=1.53-21.57). Spinal cord ischemia was also significantly associated with a grade 3 bleeding during the visceral stage (OR: 4.34, p=0.005, 95% CI=1.55-12.16) and a grade 2 renal insufficiency at 30 days (OR: 7.45, p=0.002, 95% CI=2.12-26.18).

CONCLUSION

The present study indicates that SCI is still an open issue after extent I to III TAAA endovascular repair, while its incidence in extent IV TAAA and pararenal/juxtarenal aneurysms is rare. Thoracoabdominal aortic aneurysms extension, urgent TAAA repair for rupture, severe bleeding, and 30 day renal insufficiency have been identified as significant risk factors for SCI. In the presence of such factors, adjunctive strategies may be considered to reduce SCI rates, while in low-risk patients invasive or potentially-risky maneuvers might not be justified.

Systematic review and meta-analysis of association of prophylactic cerebrospinal fluid drainage in preventing spinal cord ischemia after thoracic endovascular aortic repair

OBJECTIVE

We conducted a systemic review and meta-analysis to compare the association between prophylactic cerebrospinal fluid drainage (CSFD) vs non-CSFD in preventing spinal cord ischemia (SCI) after thoracic endovascular aortic repair (TEVAR) for aneurysm and dissection.

METHODS

The MEDLINE, Embase, and Cochrane databases were systematically searched to identify all relevant studies reported before April 1, 2020. A systematic review and meta-analysis were performed. We assessed the association between CSFD strategies, including routine CSFD vs selective CSFD or no CSFD, and the SCI rates after TEVAR for patients with aortic dissection (AD), solitary thoracic aortic aneurysm (TAA), or thoracoabdominal aortic aneurysm (TAAA). Subgroup analyses were conducted to assess the association between different aortic pathologies, including AD and thoracic aneurysms, and SCI rates after TEVAR with and without prophylactic CSFD. The data are presented as the pooled event rates (ERs) and 95% confidence intervals (CIs).

RESULTS

A total of 34 studies of 3561 patients (2671 with TAA or TAAA and 890 with type B AD) were included in the present analysis. The data are presented as the pooled ERs and 95% CIs. The overall SCI rate for patients who had undergone TEVAR with prophylactic CSFD for AD (ER, 1.80%; 95% CI, 0.88%-2.72%) was significantly lower than that for the aortic aneurysm group (ER, 5.73%; 95% CI, 4.20%-7.27%; P < .0001). The SCI rate after TEVAR with prophylactic CSFD was not significantly different from that without CSFD for AD (P = .51). No association was found between the rates of SCI after TEVAR with routine prophylactic CSFD vs selective prophylactic CSFD for aortic aneurysms (P = .76) and AD (P = .70). The SCI rate after TEVAR without CSFD for aortic aneurysms, including isolated TAA and TAAA (ER, 3.49%; 95% CI, 0.23%-6.76%) was not significantly different from that for AD (ER, 3.20%; 95% CI, 0.00%-7.20%; P = .91). For the patients with TAAAs, the rate of SCI after TEVAR with routine prophylactic CSFD was significantly lower than that with selective prophylactic CSFD (P = .04).

CONCLUSIONS

Our systematic review and meta-analysis has shown that SCI occurs more often after TEVAR for aortic aneurysms than for AD. Routine prophylactic CSFD, compared with selective CSFD, was associated with a lower rate of postoperative SCI after TEVAR for TAAAs. No significant association was found between the SCI rate and routine prophylactic CSFD for patients undergoing TEVAR for isolated TAA or AD.

Prior Infrarenal Aortic Surgery is Not Associated with Increased Risk of Spinal Cord Ischemia Following Thoracic Endovascular Aortic Repair and Complex Endovascular Aortic Repair

OBJECTIVES

Patients with prior infrarenal aortic intervention represent an increasing demographic of patients undergoing thoracic endovascular aortic repair (TEVAR) and/or complex EVAR. Studies have suggested that prior abdominal aortic surgery is a risk factor for spinal cord ischemia (SCI). However, these results are largely based on single-center experiences with limited multi-institutional and national data assessing clinical outcomes in these patients. The objective of this study was to evaluate the effect of prior infrarenal aortic surgery on SCI.

METHODS

The Society for Vascular Surgery Vascular Quality Initiative database was retrospectively reviewed to identify all patients ≥18 years old undergoing TEVAR/complex EVAR from January 2012 to June 2020. Patients with previous thoracic or suprarenal aortic repairs were excluded. Baseline and procedural characteristics and postoperative outcomes were compared by group: TEVAR/complex EVAR with or without previous infrarenal aortic repair. The primary outcome was postoperative SCI. Secondary outcomes included postoperative hospital length of stay (LOS), bowel ischemia, renal ischemia, and 30-day mortality. Multivariate regression was used to determine independent predictors of postoperative SCI. Additional analysis was performed for patients undergoing isolated TEVAR.

RESULTS

A total of 9506 patients met the inclusion criteria: 8691 (91.4%) had no history of infrarenal aortic repair and 815 (8.6%) had previous infrarenal aortic repair. Patients with previous infrarenal repair were older with an increased prevalence of chronic kidney disease (p=0.001) and cardiovascular risk factors including hypertension, chronic obstructive pulmonary disease, and smoking history (p<0.001). These patients presented with larger maximal aortic diameters (6.06±1.47 cm versus 5.15±1.76 cm; p<0.001) and required more stent grafts (p<0.001) with increased intraoperative blood transfusion requirements (p<0.001), and longer procedure times (p<0.001). Univariate analysis demonstrated no difference in postoperative SCI, postoperative hospital LOS, bowel ischemia, or renal ischemia between the two groups. Thirty-day mortality was significantly higher in patients with prior infrarenal repair (p=0.001). On multivariate regression, prior infrarenal aortic repair was not a predictor of postoperative SCI, while aortic dissection (odds ratio [OR] 1.65; 95% confidence interval [CI] 1.26-2.16, p<0.001), number of stent grafts deployed (OR 1.45; 95% CI 1.30-1.62, p<0.001), and units of packed red blood cells transfused intraoperatively (OR 1.33; 95% CI 1.03-1.73, p=0.032) were independent predictors of SCI.

CONCLUSIONS

Although TEVAR/complex EVAR patients with prior infrarenal aortic repair constituted a sicker cohort with higher 30-day mortality, the rate of SCI was comparable to patients without prior repair. Previous infrarenal repair was not associated with risk of SCI.

Biochemical, pathological and ultrastructural investigation of whether lamotrigine has neuroprotective efficacy against spinal cord ischemia reperfusion injury

INTRODUCTION

Lamotrigine, an anticonvulsant drug with inhibition properties of multi-ion channels, has been shown to be able to attenuates secondary neuronal damage by influencing different pathways. The aim of this study was to look into whether lamotrigine treatment could protect the spinal cord from experimental spinal cord ischemia-reperfusion injury.

MATERIALS AND METHODS

Thirty-two rats, eight rats per group, were randomly assigned to the sham group in which only laparotomy was performed, and to the ischemia, methylprednisolone and lamotrigine groups, where the infrarenal aorta was clamped for thirty minutes to induce spinal cord ischemia-reperfusion injury. Tissue samples belonging to spinal cords were harvested from sacrificed animals twenty-four hours after reperfusion. Tumor necrosis factor-alpha levels, interleukin-1 beta levels, nitric oxide levels, superoxide dismutase activity, catalase activity, glutathione peroxidase activity, malondialdehyde levels and caspase-3 activity were studied. Light and electron microscopic evaluations were also performed to reveal the pathological alterations. Basso, Beattie, and Bresnahan locomotor scale and the inclined-plane test was used to evaluate neurofunctional status at the beginning of the study and just before the animals were sacrificed.

RESULTS

Lamotrigine treatment provided significant improvement in the neurofunctional status by preventing the increase in cytokine expression, increased lipid peroxidation and oxidative stress, depletion of antioxidant enzymes activity and increased apoptosis, all of which contributing to spinal cord damage through different paths after ischemia reperfusion injury. Furthermore, lamotrigine treatment has shown improved results concerning the histopathological and ultrastructural scores and the functional tests.

CONCLUSION

These results proposed that lamotrigine may be a useful therapeutic agent to prevent the neuronal damage developing after spinal cord ischemia-reperfusion injury.

Luteolin Modulates the NF-E2-Related Factor 2/Glutamate-Cysteine Ligase Pathway in Rats with Spinal Cord Injury

Spinal cord ischemia-reperfusion injury (SCII) easily causes unalterable neurological deficits. We previously demonstrated that the flavonoid luteolin (LU) has strong antioxidant, anti-inflammatory, and other neuroprotective efficacies against SCII. In our current study, we examined the contributions of the NF-E2-related factor 2 (Nrf2)/glutamate-cysteine ligase (GCL) pathway to LU-mediated neuroprotection in the transient abdominal aorta occlusion rat model of SCII. Rats were divided into four groups: Sham surgery, SCII alone, SCII plus LU pretreatment (SCII + LU), and SCII plus cotreatment with LU and the Nrf2 inhibitor ML385 (SCII + LU + ML385). The Basso-Beattie-Bresnahan (BBB) scale was used to assess neurological function, hematoxylin and eosin staining to evaluate pathological change to the spinal cord, and enzyme-linked immunosorbent assay to measure tissue markers of oxidative stress and inflammation induced by SCII. Mitochondrial injury and apoptosis were examined by flow cytometry and expression levels of Nrf2, GCL catalytic subunit (GCLc), and GCL modifier subunit (GCLm) by real-time quantitative polymerase chain reaction. LU pretreatment significantly enhanced recovery of motor function as evidenced by the BBB score and attenuated the pathological damage. Furthermore, LU effectively enhanced the antioxidative activity, alleviated mitochondrial swelling, decreased the expression levels of several proinflammatory cytokines after SCII, and significantly upregulated Nrf2, GCLc, and GCLm expression levels. Cotreatment with ML385 reversed all these protective effects of LU except the anti-inflammatory response. Collectively, these findings indicate that the neuroprotective efficacy of LU depends on suppression of oxidative stress and preservation of mitochondrial function through signaling pathways involving Nrf2 activation and downstream gene expression.

Reoperative Total Arch Repair Using a Trifurcated Graft and Selective Antegrade Cerebral Perfusion

BACKGROUND

This study reviews the outcomes of our reoperative total arch repair (TAR) technique using a trifurcated graft and selective antegrade cerebral perfusion (SACP).

METHODS

Fifty patients underwent reoperative TAR from January 2005 to September 2020, with either a one-stage (N=9), or two-stage repair (N=41). The two-stage technique includes minimal dissection of the mediastinal structures, an arch-first technique using a trifurcated graft, and construction of a classical elephant trunk via a partial transverse incision distally in the old-graft or in the aorta just distal to the old graft.

RESULTS

The median age was 63 years. Chronic dissection was the most frequent indication (88%) and 98% had undergone a previous proximal aortic repair at a median interval of 3.0 years. The median cardiopulmonary bypass, myocardial ischemic, SACP, and lower body circulatory arrest times were 226, 103, 97, and 98 minutes, respectively. The minimum nasopharyngeal and bladder temperature were 16.5 °C, and 20.0 °C. Operative mortality was 2% and the incidence of stroke, and spinal cord injury (SCI) were 2%, and 0%. Stage II repair was performed in 37 patients (open: 33 patients, endovascular: 4 patients), with two mortalities and no SCI. The median duration between stage I and II was 63 days. Survival and aortic event free rates at 3 years were 88.4 ±4.9%, and 89.8 ±5.0%.

CONCLUSIONS

We report a reoperative TAR technique that minimizes dissection of the cardiac structures, simplifies the distal anastomosis, and protects vital organs, such as the brain, heart, and spinal cord.

Decision analysis and personalized clinical tool for cerebrospinal fluid drains in thoracoabdominal aortic aneurysms repair

BACKGROUND AND AIM

The routine use of cerebrospinal fluid (CSF) drainage in patients undergoing operative repair of thoracoabdominal aneurysms (TAAA) has been associated with decreased rates of spinal cord ischemia. The use of CSF drains is not without consequence, however with complications including subarachnoid hemorrhage, epidural hematoma, meningitis, and, in 1% of cases, death. To date, a decision analysis tool to help clinicians decide when to use and not to use a CSF drain does not exist. In this analysis, we set out to develop a decision analysis tool for CSF drain placement in patients undergoing operative repair of TAAA.

METHODS

A Markov state-transition cohort model that compared TAAA repair with adjunctive CSF drain insertion to TAAA repair without drain insertion for the outcome of life expectancy was developed in TreeAge 2020. The cycle length was 1 month and the time horizon was 60 months.

RESULTS

The use of a CSF drain was associated with improved 5-year life expectancy (3.21 ± 0.10 vs. 3.09 ± 0.11 life-years gained). In the sensitivity analysis that varied the effectiveness of a CSF drain (odds ratio closer to 1 = less effective), the use of a CSF drain resulted in higher life expectancy in almost all scenarios.

CONCLUSIONS

The routine use of a CSF drain in patients undergoing TAAA repair is safe and effective, with few exceptions. This decision analysis tool can be used by clinicians to develop a personalized approach.

Interventions to improve perioperative neurologic outcomes

PURPOSE OF REVIEW

Few outcomes in surgery are as important to patients as that of their neurologic status. The purpose of this review is to discuss and categorize the most common perioperative neurologic complications. We will also discuss strategies to help prevent and mitigate these complications for our patients.

RECENT FINDINGS

There are several strategies the anesthesiologist can undertake to prevent or treat conditions, such as perioperative neurocognitive disorders, spinal cord ischemia, perioperative stroke, and postoperative visual loss.

SUMMARY

A thorough understanding of threats to patients' neurologic well-being is essential to excellent clinical practice.

Baicalein Attenuates Pyroptosis and Endoplasmic Reticulum Stress Following Spinal Cord Ischemia-Reperfusion Injury via Autophagy Enhancement

Background

Spinal cord ischemia-reperfusion injury (SCIRI) is the main complication after the repair of a complex thoracoabdominal aortic aneurysm. Many clinical treatments are not ideal due to the complex pathophysiological process of this injury. Baicalein (BA), a component derived from the roots of the herb Scutellaria baicalensis, may contribute to the successful treatment of ischemia/reperfusion injury.

Purpose

In the present study, the effects of BA on spinal cord ischemia-reperfusion injury and the underlying mechanisms were assessed.

Materials and Methods

Spinal cord ischemia was induced in C57BL/6 mice by blocking the aortic arch. Fifty-five mice were then randomly divided into four groups: Sham, SCIR+Vehicle, SCIR+BA, and SCIR+BA +3MA groups. At 0 and 24 h pre-SCIRI and at 24 h and 7 days post-SCIRI, evaluations with the Basso mouse scale (BMS) were performed. On postoperative 24 h, the spinal cord was harvested to assess pyroptosis, endoplasmic reticulum stress mediated apoptosis and autophagy.

Results

BA enhanced the functional recovery of spinal cord ischemia-reperfusion injury. In addition, BA attenuated pyroptosis, alleviated endoplasmic reticulum stress-mediated apoptosis, and activated autophagy. However, the effects of BA on the functional recovery of SCIRI, pyroptosis and endoplasmic reticulum stress-mediated apoptosis were reversed by the inhibition of autophagy.

Conclusions

In general, our findings revealed that BA enhances the functional recovery of spinal cord ischemia-reperfusion injury by dampening pyroptosis and alleviating endoplasmic reticulum stress-mediated apoptosis, which are mediated by the activation of autophagy.

Astaxanthin alleviates spinal cord ischemia-reperfusion injury via activation of PI3K/Akt/GSK-3β pathway in rats

BACKGROUND

Ischemia-reperfusion injury of the spinal cord (SCII) often leads to unalterable neurological deficits, which may be associated with apoptosis induced by oxidative stress and inflammation. Astaxanthin (AST) is a strong antioxidant and anti-inflammatory agent with multitarget neuroprotective effects. This study aimed to investigate the potential therapeutic effects of AST for SCII and the molecular mechanism.

METHODS

Rat models of SCII with abdominal aortic occlusion for 40 min were carried out to investigate the effects of AST on the recovery of SCII. Tarlov's scores were used to assess the neuronal function; HE and TUNEL staining were used to observe the pathological morphology of lesions. Neuron oxidative stress and inflammation were measured using commercial detection kits. Flow cytometry was conducted to assess the mitochondrial swelling degree. Besides, Western blot assay was used to detect the expression of PI3K/Akt/GSK-3β pathway-related proteins, as well as NOX2 and NLRP3 proteins.

RESULTS

The results demonstrated that AST pretreatment promoted the hind limb motor function recovery and alleviated the pathological damage induced by SCII. Moreover, AST significantly enhanced the antioxidative stress response and attenuated mitochondrial swelling. However, AST pretreatment hardly inhibited the levels of proinflammatory cytokines after SCII. Most importantly, AST activated p-Akt and p-GSK-3β expression levels. Meanwhile, cotreatment with LY294002 (a PI3K inhibitor) was found to abolish the above protective effects observed with the AST pretreatment.

CONCLUSION

Overall, these results suggest that AST pretreatment not only mitigates pathological tissue damage but also effectively improves neural functional recovery following SCII, primarily by alleviating oxidative stress but not inhibiting inflammation. A possible underlying molecular mechanism of AST may be mainly attributed to the activation of PI3K/Akt/GSK-3β pathway.

Salidroside Ameliorates Mitochondria-Dependent Neuronal Apoptosis after Spinal Cord Ischemia-Reperfusion Injury Partially through Inhibiting Oxidative Stress and Promoting Mitophagy

Ischemia-reperfusion injury is the second most common injury of the spinal cord and has the risk of neurological dysfunction and paralysis, which can seriously affect patient quality of life. Salidroside (Sal) is an active ingredient extracted from Herba Cistanche with a variety of biological attributes such as antioxidant, antiapoptotic, and neuroprotective activities. Moreover, Sal has shown a protective effect in ischemia-reperfusion injury of the liver, heart, and brain, but its effect in ischemia-reperfusion injury of the spinal cord has not been elucidated. Here, we demonstrated for the first time that Sal pretreatment can significantly improve functional recovery in mice after spinal cord ischemia-reperfusion injury and significantly inhibit the apoptosis of neurons both in vivo and in vitro. Neurons have a high metabolic rate, and consequently, mitochondria, as the main energy-supplying suborganelles, become the main injury site of spinal cord ischemia-reperfusion injury. Mitochondrial pathway-dependent neuronal apoptosis is increasingly confirmed by researchers; therefore, Sal's effect on mitochondria naturally attracted our attention. By means of a range of experiments both in vivo and in vitro, we found that Sal can reduce reactive oxygen species production through antioxidant stress to reduce mitochondrial permeability and mitochondrial damage, and it can also enhance the PINK1-Parkin signaling pathway and promote mitophagy to eliminate damaged mitochondria. In conclusion, our results show that Sal is beneficial to the protection of spinal cord neurons after ischemia-reperfusion injury, mainly by reducing apoptosis associated with the mitochondrial-dependent pathway, among which Sal's antioxidant and autophagy-promoting properties play an important role.

Previous thoracic aortic repair is not associated with adverse outcomes after thoracic endovascular aortic repair

BACKGROUND

As many as 20% of patients who have undergone previous thoracic aortic repair will require reintervention, which could entail thoracic endovascular aortic repair (TEVAR). A paucity of data is available on mortality and the incidence of spinal cord ischemia (SCI) and other postoperative complications associated with TEVAR after previous aortic repairs exclusive to the thoracic aorta. The aim of the present study was to assess the effect of previous thoracic aortic repair on the 30-day mortality and SCI outcomes for patients after TEVAR.

METHODS

The Society for Vascular Surgery Vascular Quality Initiative database was queried for all cases of TEVAR from 2012 to 2018. Patients were excluded if they had undergone previous abdominal aortic repair, the TEVAR had extended beyond aortic zone 5, or SCI data were missing. The 3 cohorts compared were TEVAR with previous ascending aortic or aortic arch repair (group 1), TEVAR with previous descending thoracic aortic repair (group 2), and TEVAR without previous repair (group 3). The primary outcomes of interest were 30-day mortality and SCI. The secondary outcomes included stroke, myocardial infarction, cardiac complications, respiratory complications, postoperative length of stay, and reintervention. The patient variables were compared using χ2 tests, analysis of variance, or Kruskal-Wallis tests, as appropriate. Logistic regression analysis was performed to identify the predictors of 30-day mortality and SCI.

RESULTS

A total of 4010 patients met the inclusion criteria, with 470 in group 1, 132 in group 2, and 3408 in group 3. The 30-day mortality was 4% (19 of 470) in group 1, 6% (8 of 132) in group 2, and 6% (213 of 3408) in group 3 (P = .17). The incidence of SCI was 3% (14 of 470) in group 1, 3% (4 of 132) in group 2, and 3.8% (128 of 3408) in group 3 (P = .65). Stroke, reintervention, myocardial infarction, and cardiac complications were not significantly different among the 3 groups. The incidence of respiratory complications was greatest for group 3 (11%; 360 of 3408) compared with groups 1 (9%; 44 of 470) and 2 (4%; 5 of 132; P = .034). Similarly, the postoperative length of stay was longest for group 3 (9.6 ± 19.4 days vs 8.2 ± 18.3 days for group 1 and 5.9 ± 8.6 days for group 2; P = .038). The independent predictors of 30-day mortality for all TEVAR patients included units of packed red blood cells transfused intraoperatively, urgent or emergent repairs, older age, increasing serum creatinine level, inability to perform self-care, total procedure time, occlusion of the left subclavian artery intraoperatively, distal endograft landing zone 5, and diabetes. The predictors of SCI included the total procedure time, urgent and emergent repairs, and increasing serum creatinine level.

CONCLUSIONS

TEVAR after previous thoracic aortic repair was not associated with an increased risk of SCI or 30-day mortality compared with TEVAR without previous aortic repair.

Incidence, predictors, and outcomes of spinal cord ischemia in elective complex endovascular aortic repair: An analysis of health insurance claims

OBJECTIVE

This study aimed to determine predictors and outcomes associated with spinal cord ischemia (SCI) after elective fenestrated or branched endovascular aneurysm repair (F/BEVAR) of thoracoabdominal aortic aneurysm (TAAA), abdominal aortic aneurysm (AAA), or aortic dissection.

METHODS

Health insurance claims data of Germany's third largest insurance provider, DAK-Gesundheit, were used to investigate SCI in elective F/BEVAR performed between 2008 and 2017. The International Classification of Diseases and German Operation and Procedure Classification System were used. We stratified the results into F/BEVAR with one or two (AAA) vs three or more (TAAA) fenestrations or branches.

RESULTS

A total of 877 patients (18.9% female; 5.8% with SCI) matching the inclusion criteria were identified during the study period. SCI occurred more often after F/BEVAR of TAAA vs AAA (10.7% vs 3.0%; P < .001). SCI was associated with female sex in the AAA group (odds ratio, 3.87; 95% confidence interval [CI], 1.25-11.15; P = .014) and with cardiac arrhythmias in the TAAA group (odds ratio, 2.98; 95% CI, 1.24-7.06; P = .013). Compared with patients without SCI, SCI patients were more likely to suffer from drug use disorders (eg, opioids, cannabinoids, sedatives) in the TAAA group (17.6% vs 2.1%; P < .05). After F/BEVAR of TAAA, the occurrence of SCI was associated with higher 90-day mortality (14.7% vs 1.1%; P < .05), longer postoperative hospital stay (22 vs 9 days; P < .05), and severe adverse events, such as acute respiratory insufficiency (44.1% vs 12.7%), acute renal failure (35.3% vs 11.3%), and pneumonia (29.4% vs 4.9%; all P < .05). In adjusted analyses, SCI was associated with worse long-term survival after F/BEVAR for TAAA (hazard ratio, 2.54; 95% CI, 1.37-4.73; P < .003).

CONCLUSIONS

Female AAA patients and TAAA patients with cardiac arrhythmias are at highest risk for development of SCI after F/BEVAR. The occurrence of this event was strongly associated with higher major complication rates and worse short-term and long-term survival. This emphasizes a need to further illuminate the value of spinal cord protection protocols in F/BEVAR.

The casual association of cervical spinal cord ischemia and axonal degeneration in second motor neuron following subarachnoid hemorrhage: Experimental study

AIM

Muscle abnormalities after spinal cord ischemia caused by subarachnoid hemorrhage (SAH) have not been explored for degenerative variations in the soma of second motor neurons of the spinal cord gray matter. This study aimed to investigate histopathological alterations in the gray matter and the role of peripheral nerves in SAH.

MATERIAL AND METHODS

Twenty-two rabbits were allocated in the control (Group I, n = 5), SHAM (Group II, n = 5), and research (Group III, n = 12) groups. Muscle weakness of the upper extremities innervated by radial nerves was evaluated at the initial day, and outcomes were recorded as control data. Re-measurements were done after injecting 0.5 ml of SF for SHAM and autolog artery blood inside craniocervical subarachnoid space for the study group. After 3 weeks, radial nerve roots, their ganglia, and segments of the spinal cord around C5-6 root entry zones were extracted bilaterally. Degenerated second motor neuron somas and the degenerated radial nerve motor axons at the intervertebral foramen were assessed.

RESULTS

The average degenerated soma intensity/mm³ at the C5-6 levels in the spinal cord was 2 ± 1/mm³, 13 ± 4/mm³, and 56 ± 10/mm³ for Groups I, II, and Group III. The average degenerated axon intensity of radial nerves was 3 ± 1/mm², 34 ± 9/mm², and 234 ± 78/mm² for Groups I, II, and III.

CONCLUSION

Gray matter ischemia in the spinal cord may lead to axonal deterioration on equal levels at the peripheral nerves with advanced SAH. Detected or undetected spinal SAH should be considered an important factor on the etiology of second motor neuron diseases.

Anti-Inflammatory Effect of Lycopene on Experimental Spinal Cord Ischemia Injury via Cyclooxygenase-2 Suppression

OBJECTIVE

Spinal cord ischemia/reperfusion injury (SCII) is a devastating complication following thoracoabdominal aortic surgeries, often leading to severe neurological deficits. We sought to examine the effects of lycopene, a naturally existing carotenoid with anti-inflammatory properties, in the treatment against SCII.

METHODS

Rats were assigned into four treatment groups: Sham (sham operation), SCII (SCII-induction), LY25, and LY50 (lycopene treatment at 25 or 50 mg/kg following SCII induction, respectively).

RESULTS

Lycopene treatment improved the recovery of neurological functions following SCII and suppressed the neuronal cell death and neuroinflammation at 14 days after SCII. Furthermore, Western blot assay revealed that lycopene treatment attenuated the SCII-induced increase in the protein levels of cyclooxygenase-2 (COX-2), nuclear factor-κB, and activate protein-1, as well as the reduction of heme oxygenase-1.

CONCLUSION

Lycopene exerted neuroprotective functions in SCII and inhibited SCII-elicited neuroinflammation via COX-2 suppression.

Erythropoietin's Beta Common Receptor Mediates Neuroprotection in Spinal Cord Neurons

BACKGROUND

Paraplegia from spinal cord ischemia-reperfusion (SCIR) remains an elusive and devastating complication of complex aortic operations. Erythropoietin (EPO) attenuates this injury in models of SCIR. Upregulation of the EPO beta common receptor (βcR) is associated with reduced damage in models of neural injury. The purpose of this study was to examine whether EPO-mediated neuroprotection was dependent on βcR expression. We hypothesized that spinal cord neurons subjected to oxygen-glucose deprivation would mimic SCIR injury in aortic surgery and EPO treatment attenuates this injury in a βcR-dependent fashion.

METHODS

Lentiviral vectors with βcR knockdown sequences were tested on neuron cell cultures. The virus with greatest βcR knockdown was selected. Spinal cord neurons from perinatal wild-type mice were harvested and cultured to maturity. They were treated with knockdown or nonsense virus and transduced cells were selected. Three groups (βcR knockdown virus, nonsense control virus, no virus control; n = 8 each) were subjected to 1 hour of oxygen-glucose deprivation. Viability was assessed. βcR expression was quantified by immunoblot.

RESULTS

EPO preserved neuronal viability after oxygen-glucose deprivation (0.82 ± 0.04 versus 0.61 ± 0.01; p < 0.01). Additionally, EPO-mediated neuron preservation was similar in the nonsense virus and control mice (0.82 ± 0.04 versus 0.80 ± 0.05; p = 0.77). EPO neuron preservation was lost in βcR knockdown mice compared with nonsense control mice (0.46 ± 0.03 versus 0.80 ± 0.05; p < 0.01).

CONCLUSIONS

EPO attenuates neuronal loss after oxygen-glucose deprivation in a βcR-dependent fashion. This receptor holds immense clinical promise as a target for pharmacotherapies treating spinal cord ischemic injury.

Spinal cord injury as a complication of thoracic endovascular aneurysm repair

OBJECTIVE

Spinal cord ischemia (SCI) is a devastating complication of thoracic aortic aneurysm repair in the era of thoracic endovascular aneurysm repair (TEVAR). This review aims to clarify the causes of SCI during TEVAR and to propose ways that it may be prevented.

METHODS AND RESULTS

We performed an extensive literature search of SCI during TEVAR. Based on the existing literature, we examined the anatomy of the anterior spinal cord artery, which supplies blood to the anterior aspect of the spinal cord, and discuss reported effective ways to prevent SCI during TEVAR, including augmentation of arterial blood pressure and drainage of cerebrospinal fluid.

CONCLUSION

After reviewing the mechanism of SCI during TEVAR, we evaluated promising preventative measures.

Spinal Cord Neurons Isolation and Culture from Neonatal Mice

We present a protocol for the isolation and culture of spinal cord neurons. The neurons are obtained from neonatal C57BL/6 mice and are isolated on postnatal day 1-3. A mouse litter, usually 4-10 pups born from one breeding pair, is gathered for one experiment, and spinal cords are collected individually from each mouse after euthanasia with isoflurane. The spinal column is dissected out and then the spinal cord is released from the column. The spinal cords are then minced to increase the surface area of delivery for an enzymatic protease that allows for the neurons and other cells to be released from the tissue. Trituration is then used to release the cells into solution. This solution is subsequently fractionated in a density gradient to separate the various cells in solution, allowing for neurons to be isolated. Approximately 1-2.5 x 10⁶ neurons can be isolated from one litter group. The neurons are then seeded onto wells coated with adhesive factors that allow for proper growth and maturation. The neurons take approximately 7 days to reach maturity in the growth and culture medium and can be used thereafter for treatment and analysis.

Nicotinamide Adenine Dinucleotide Protects against Spinal Cord Ischemia Reperfusion Injury-Induced Apoptosis by Blocking Autophagy

The role of autophagy, neuroprotective mechanisms of nicotinamide adenine dinucleotide (NAD⁺), and their relationship in spinal cord ischemic reperfusion injury (SCIR) was assessed. Forty-eight Sprague-Dawley rats were divided into four groups: sham, ischemia reperfusion (I/R), 10 mg/kg NAD⁺, and 75 mg/kg NAD⁺. Western blotting, immunofluorescence, and immunohistochemistry were used to assess autophagy and apoptosis. Basso, Beattie, and Bresnahan (BBB) scores were used to assess neurological function. Expression levels of Beclin-1, Atg12-Atg5, LC3B-II, cleaved caspase 3, and Bax were upregulated in the I/R group and downregulated in the 75 mg/kg NAD⁺ group; p-mTOR, p-AKT, p62, and Bcl-2 were downregulated in the I/R group and upregulated in the 75 mg/kg NAD⁺ group. Numbers of LC3B-positive, caspase 3-positive, Bax-positive, and TUNEL-positive cells were significantly increased in the I/R group and decreased in the 75 mg/kg NAD⁺ group. The mean integrated option density of Bax increased and that of Nissl decreased in the I/R group, and it decreased and increased, respectively, in the 75 mg/kg NAD⁺ group. BBB scores significantly increased in the 75 mg/kg NAD⁺ group relative to the I/R group. No difference was observed between I/R and 10 mg/kg NAD⁺ groups for these indicators. Therefore, excessive and sustained autophagy aggravates SCIR; administration of NAD⁺ alleviates injury.

Methane ameliorates spinal cord ischemia-reperfusion injury in rats: Antioxidant, anti-inflammatory and anti-apoptotic activity mediated by Nrf2 activation

Methane is reported to have antioxidant, anti-inflammatory and anti-apoptotic properties. We investigated the potential neuroprotective effects of methane-rich saline (MS) on spinal cord ischemia-reperfusion injury and determined that its therapeutic benefits are associated with the activation of nuclear factor erythroid 2-related factor 2 (Nrf2). Rats received 9min of spinal cord ischemia induced by occlusion of the descending thoracic aorta plus systemic hypotension followed by a single MS treatment (10ml/kg, ip) and 72h reperfusion. MS treatment attenuated motor sensory deficits and produced high concentrations of methane in spinal cords during reperfusion, which increased Nrf2 expression and transcriptional activity in neurons, microglia and astrocytes in the ventral, intermediate and dorsal gray matter of lumbar segments. Heme oxygenase-1, superoxide dismutase, catalase and glutathione were upregulated; and glutathione disulfide, superoxide, hydrogen peroxide, malondialdehyde, 8-hydroxy-2-deoxyguanosine and 3-nitrotyrosine were downregulated in MS-treated spinal cords. MS treatment reduced neuronal apoptosis in gray matter zones, which was consistent with the suppression of cytochrome c release to the cytosol from the mitochondria and the activation of caspase-9 and -3. Throughout the gray matter, the activation of microglia and astrocytes was inhibited; the nuclear accumulation of phosphorylated nuclear factor-kappa B p65 was reduced; and tumor necrosis factor α, interleukin 1β, chemokine (C-X-C motif) ligand 1, intercellular adhesion molecule 1 and myeloperoxidase were decreased. MS treatment attenuated blood-spinal cord barrier dysfunction by preventing the expression and activity of matrix metallopeptidase-9 and disrupting tight junction proteins. Consecutive intrathecal injection of specific siRNAs targeting Nrf2 at 24-h intervals 3 days before ischemia reduced the beneficial effects of MS. Our data indicate that MS treatment prevents IR-induced spinal cord damage via antioxidant, anti-inflammatory and anti-apoptotic activities that involve the activation of Nrf2 signaling. Thus, methane may serve as a novel promising therapeutic agent for treating ischemic spinal cord injury.

Protective effect of nicotinamide adenine dinucleotide (NAD+) against spinal cord ischemia-reperfusion injury via reducing oxidative stress-induced neuronal apoptosis

As previous studies demonstrate that oxidative stress and apoptosis play crucial roles in ischemic pathogenesis and nicotinamide adenine dinucleotide (NAD⁺) treatment attenuates oxidative stress-induced cell death among primary neurons and astrocytes as well as significantly reduce cerebral ischemic injury in rats. We used a spinal cord ischemia injury (SCII) model in rats to verify our hypothesis that NAD⁺ could ameliorate oxidative stress-induced neuronal apoptosis. Adult male rats were subjected to transient spinal cord ischemia for 60min, and different doses of NAD⁺ were administered intraperitoneally immediately after the start of reperfusion. Neurological function was determined by Basso, Beattie, Bresnahan (BBB) scores. The oxidative stress level was assessed by superoxide dismutase (SOD) activity and malondialdehyde (MDA) content. The degree of apoptosis was analyzed by deoxyuridinetriphosphate nick-end labeling (TUNEL) staining and protein levels of cleaved caspase-3 and AIF (apoptosis inducing factor). The results showed that NAD⁺ at 50 or 100mg/kg significantly decreased the oxidative stress level and neuronal apoptosis in the spinal cord of ischemia-reperfusion rats compared with saline, as accompanied with the decreased oxidative stress, NAD⁺ administration significantly restrained the neuronal apoptosis after ischemia injury while improved the neurological and motor function. These findings suggested that NAD⁺ might protect against spinal cord ischemia-reperfusion via reducing oxidative stress-induced neuronal apoptosis.

Spinal Cord Inflammation: Molecular Imaging after Thoracic Aortic Ischemia Reperfusion Injury

Purpose To evaluate whether noninvasive molecular imaging technologies targeting myeloperoxidase (MPO) can reveal early inflammation associated with spinal cord injury after thoracic aortic ischemia-reperfusion (TAR) in mice. Materials and Methods The study was approved by the institutional animal care and use committee. C57BL6 mice that were 8-10 weeks old underwent TAR (n = 55) or sham (n = 26) surgery. Magnetic resonance (MR) imaging (n = 6) or single photon emission computed tomography (SPECT)/computed tomography (CT) (n = 15) studies targeting MPO activity were performed after intravenous injection of MPO sensors (bis-5-hydroxytryptamide-tetraazacyclododecane [HT]-diethyneletriaminepentaacetic acid [DTPA]-gadolinium or indium 111-bis-5-HT-DTPA, respectively). Immunohistochemistry and flow cytometry were used to identify myeloid cells and neuronal loss. Proinflammatory cytokines, keratinocyte chemoattractant (KC), and interleukin 6 (IL-6) were measured with enzyme-linked immunosorbent assay. Statistical analyses were performed by using nonparametric tests and the Pearson correlation coefficient. P < .05 was considered to indicate a significant difference. Results Myeloid cells infiltrated into the injured cord at 6 and 24 hours after TAR. MR imaging confirmed the presence of ischemic lesions associated with mild MPO-mediated enhancement in the thoracolumbar spine at 24 hours compared with the sham procedure. SPECT/CT imaging of MPO activity showed marked MPO-sensor retention at 6 hours (P = .003) that continued to increase at 24 hours after TAR (P = .0001). The number of motor neurons decreased substantially at 24 hours after TAR (P < .01), which correlated inversely with in vivo inflammatory changes detected at molecular imaging (r = 0.64, P = .0099). MPO was primarily secreted by neutrophils, followed by lymphocyte antigen 6 complex^high monocytes and/or macrophages. There were corresponding increased levels of proinflammatory cytokines KC (P = .0001) and IL-6 (P = .0001) that mirrored changes in MPO activity. Conclusion MPO is a suitable imaging biomarker for identifying and tracking inflammatory damage in the spinal cord after TAR in a mouse model. ^© RSNA, 2016 Online supplemental material is available for this article.

Neuroprotective effects of thymoquinone against spinal cord ischemia-reperfusion injury by attenuation of inflammation, oxidative stress, and apoptosis

OBJECTIVE

Ischemia-reperfusion (I/R) injury of the spinal cord following thoracoabdominal aortic surgery remains the most devastating complication, with a life-changing impact on the patient. Thymoquinone (TQ), the main constituent of the volatile oil from Nigella sativa seeds, is reported to possess strong antioxidant, antiinflammatory, and antiapoptotic properties. This study investigated the effects of TQ administration following I/R injury to the spinal cord.

METHODS

Thirty-two rats were randomly allocated into 4 groups. Group 1 underwent only laparotomy. For Group 2, aortic clip occlusion was introduced to produce I/R injury. Group 3 was given 30 mg/kg of methylprednisolone intraperitoneally immediately after the I/R injury. Group 4 was given 10 mg/kg of TQ intraperitoneally for 7 days before induction of spinal cord I/R injury, and administration was continued until the animal was euthanized. Locomotor function (Basso, Beattie, and Bresnahan scale and inclined plane test) was assessed at 24 hours postischemia. Spinal cord tissue samples were harvested to analyze tissue concentrations of malondialdehyde, nitric oxide, tumor necrosis factor–α, interleukin-1, superoxide dismutase, glutathione-peroxidase, catalase, and caspase-3. In addition, histological and ultrastructural evaluations were performed.

RESULTS

Thymoquinone treatment improved neurological outcome, which was supported by decreased levels of oxidative products (malondialdehyde and nitric oxide) and proinflammatory cytokines (tumor necrosis factor–α and interleukin-1), increased activities of antioxidant enzymes (superoxide dismutase, glutathione-peroxidase, and catalase), as well as reduction of motor neuron apoptosis. Light microscopy and electron microscopy results also showed preservation of tissue structure in the treatment group.

CONCLUSIONS

As shown by functional, biochemical, histological, and ultrastructural analysis, TQ exhibits an important protective effect against I/R injury of the spinal cord.