Prevention of spinal cord ischaemia during descending thoracic and thoracoabdominal aortic surgery

Ginsenoside Rd: A promising target for ischemia-reperfusion injury therapy (A mini review)

Ischemia-reperfusion injury (IRI) represents a prevalent pathological phenomenon. Traditional treatment approaches primarily aim at restoring blood supply to ischemic organs, disregarding the consequent damage caused by IRI. Belonging to the class of protopanaxadiol ginsenosides that are found in Panax ginseng, ginsenoside Rd (GSRd) demonstrates notable safety alongside a diverse range of biological functions. Its active components exhibit diverse pharmacological effects, encompassing anti-inflammatory, anti-tumor, neuroprotective, cardiovascular-protective, and immune-regulatory properties, making it a promising candidate for addressing multiple medical conditions. GSRd shields against I/R injury by employing crucial cellular mechanisms, including the attenuation of oxidative stress, reduction of inflammation, promotion of cell survival signaling pathways, and inhibition of apoptotic pathways. Additionally, GSRd regulates mitochondrial function, maintains calcium homeostasis, and modulates the expression of genes involved in I/R injury. This review seeks to consolidate the pharmacological mechanism of action of GSRd within the context of IRI. Our objective is to contribute to the advancement of GSRd-related pharmaceuticals and provide novel insights for clinicians involved in developing IRI treatment strategies.

Delayed Paraparesis: An Unusual Complication Following Coarctation of Aorta Repair

ABSTRACT

Paraparesis following cardiac surgery is a manifestation of spinal cord injury (SCI). It can occur in any aortic surgery from the aneurysm to the coarctation of the aorta (CoA) where the cross-clamp of the aorta is applied. Though the incidence of paraplegia is low, its occurrence affects the morbidity and mortality of the patient. There are only sporadic case reports on the development of paraplegia following recurrent and technically challenging repair of CoA. However, the spontaneous development of paraplegia has also been reported in cases of unoperated CoA. The present report describes the case of delayed SCI in which paraparesis developed 5 days post a coarctation repair. The risk factors and strategies to protect the spinal cord during aortic surgeries are emphasized.

miR-872-5p/FOXO3a/Wnt signaling feed-forward loop promotes proliferation of endogenous neural stem cells after spinal cord ischemia-reperfusion injury in rats

The activation of endogenous neural stem cells (NSCs) is considered an important mechanism of neural repair after mechanical spinal cord injury; however, whether endogenous NSC proliferation can also occur after spinal cord ischemia-reperfusion injury (SCIRI) remains unclear. In this study, we aimed to verify the existence of endogenous NSC proliferation after SCIRI and explore the underlying molecular mechanism. NSC proliferation was observed after SCIRI in vivo and oxygen-glucose deprivation and reperfusion (OGD/R) in vitro, accompanied by a decrease in forkhead box protein O 3a (FOXO3a) expression. This downward trend was regulated by the increased expression of microRNA-872-5p (miR-872-5p). miR-872-5p affected NSC proliferation by targeting FOXO3a to increase the expression of β-catenin and T-cell factor 4 (TCF4). In addition, TCF4 in turn acted as a transcription factor to increase the expression level of miR-872-5p, and knockdown of FOXO3a enhanced the binding of TCF4 to the miR-872-5p promoter. In conclusion, SCIRI in vivo and OGD/R in vitro stimulated the miR-872-5p/FOXO3a/β-catenin-TCF4 pathway, thereby promoting NSC proliferation. At the same time, FOXO3a affected TCF4 transcription factor activity and miR-872-5p expression, forming a positive feedback loop that promotes NSC proliferation.

Effects of Dexmedetomidine Administered Through Different Routes on Kidney Tissue in Rats with Spinal Cord Ischaemia–Reperfusion Injury

Background

Ischaemia–reperfusion (IR) injury, which can be encountered during surgical procedures involving the abdominal aorta, is a complex process that affects distant organs, such as the heart, liver, kidney, and lungs, as well as the lower extremities. In this study, we aimed to contribute to the limited literature by investigating the protective effect of dexmedetomidine, which was administered through different routes, on kidney tissue in rats with spinal cord IR injury.

Methods

A total of 30 rats were randomly divided into five groups: control (C group), IR (IR group), IR-intraperitoneal dexmedetomidine (IRIPD group), IR-intrathecal dexmedetomidine (IRITD group), and IR-intravenous dexmedetomidine (IRIVD group). The spinal cord IR model was established. Dexmedetomidine was administered at doses of 100 µg/kg intraperitoneally, 3 µg/kg intrathecally, and 9 µg/kg intravenously. Histopathologic parameters in kidney tissue samples taken at the end of the reperfusion period and biochemical parameters in serum were evaluated.

Results

When examined histopathologically, tubular dilatation was found to be significantly reduced in the IRIVD, IRITD, and IRIPD groups compared with the IR group (p = 0.012, all). Vascular vacuolization and hypertrophy were significantly decreased in the IRIVD, IRITD, and IRIPD groups compared with the IR group (p = 0.006, all). Tubular cell degeneration and necrosis were significantly reduced in the IRIVD, IRITD, and IRIPD groups compared with the IR group (p = 0.008, p = 0.08, and p = 0.030, respectively). Lymphocyte infiltration was significantly decreased in the IRIVD and IRITD groups compared with the IR group (p = 0.006 and p = 0.06, respectively).

Conclusion

It was observed that dexmedetomidine administered by different routes improved the damage caused by IR in kidney histopathology. We think that the renoprotective effects of dexmedetomidine administered intravenously and intrathecally before IR in rats are greater.

Effects of Ganoderma lucidum Polysaccharides on Different Pathways Involved in the Development of Spinal Cord Ischemia Reperfusion Injury: Biochemical, Histopathologic, and Ultrastructural Analysis in a Rat Model

OBJECTIVE

Inflammation and oxidative stress are 2 important factors in the emergence of paraplegia associated with spinal cord ischemia-reperfusion injury (SCIRI) after thoracoabdominal aortic surgery. Here it is aimed to investigate the effects of Ganoderma lucidum polysaccharide (GLPS) on SCIRI.

METHODS

Rats were randomly selected into 4 groups of 8 animals each: sham, ischemia, methylprednisolone, and GLPS. To research the impacts of various pathways that are efficacious in formation of SCIRI, tumor necrosis factor α, interleukin 1β, nitric oxide, superoxide dismutase levels, and catalase, glutathione peroxidase activities, malondialdehyde levels, and caspase-3 activity were measured in tissues taken from the spinal cord of rats in all groups killed 24 hours after ischemia reperfusion injury. The Basso, Beattie, and Bresnahan locomotor scale and inclined plane test were used for neurologic assessment before and after SCIRI. In addition, histologic and ultrastructural analyses of tissue samples in all groups were performed.

RESULTS

SCIRI also caused marked increase in tissue tumor necrosis factor α, interleukin 1β, nitric oxide, malondialdehyde levels, and caspase-3 activity, because of inflammation, increased free radical generation, lipid peroxidation, and apoptosis, respectively. On the other hand, SCIRI caused significant reduction in tissue superoxide dismutase, glutathione peroxidase, and catalase activities. Pretreatment with GLPS likewise diminished the level of the spinal cord edema, inflammation, and tissue injury shown by pathologic and ultrastructural examination. Pretreatment with GLPS reversed all these biochemical changes and improved the altered neurologic status.

CONCLUSIONS

These outcomes propose that pretreatment with GLPS prevents progression of SCIRI by alleviating inflammation, oxidation, and apoptosis.

Point-of-care Ultrasound Diagnosis of Acute Abdominal Aortic Occlusion

Acute aortic occlusion is an emergent vascular condition not encountered routinely. Given its varied presentations, including neurovascular deficits and mimicking an acute abdomen, the diagnosis is often delayed causing increased morbidity and mortality. We present a case of acute abdominal aortic occlusion masquerading as sudden onset lower extremity pain and weakness in an 86-year-old female requiring emergent thrombectomy. This is only the second case report to discuss the use of point-of-care ultrasound to expedite diagnosis and management.1

Changes in long non-coding RNA transcriptomic profiles after ischemia-reperfusion injury in rat spinal cord

With the aim of exploring expression profiles and biological functions of long non-coding RNA (lncRNA) and mRNAs after spinal cord ischemia-reperfusion injury (SCII), differentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs) in rat spinal cords were identified following SCII through high-throughput RNA sequencing. In total, 1,455 lncRNAs and 6,707 mRNAs were observed to be differentially expressed (—Fold Change— ≥ 2 and P < 0.05) after SCII, including 761 up-regulated and 694 down-regulated lncRNAs, 3,772 up-regulated and 2,935 down-regulated mRNAs. Gene ontology and KEGG pathway analysis showed that the DElncRNAs and DEmRNAs were implicated in many different biological processes and pathways. Further, lncRNA-mRNA co-expression networks were built to explore the potential roles of these DElncRNAs. Our results demonstrate genome-wide lncRNA and mRNA expression patterns in spinal cords after SCII, which may play vital roles in post-SCII pathophysiological processes. These findings are important for future functional research on the lncRNAs involved in SCII and might be critical for providing new insight into identification of potential targets for SCII therapy.

Spinal cord injury following aortic arch replacement

PURPOSE

Postoperative spinal cord injury is a devastating complication after aortic arch replacement. The purpose of this study was to determine the predictors of this complication.

METHODS

A group of 254 consecutive patients undergoing aortic arch replacement via median sternotomy, with (n = 78) or without (n = 176) extended replacement of the upper descending aorta, were included in a risk analysis. The frozen elephant trunk technique was used in 46 patients. The patients' atherothrombotic lesions (extensive intimal thickening of > 4 mm) were identified from computed tomography images.

RESULTS

Complete paraplegia (n = 7) and incomplete paraparesis (n = 4) occurred immediately after the operation (permanent spinal cord injury rate, 1.97%; transient spinal cord injury rate, 2.36%). A multivariable logistic regression analysis identified the use of the frozen elephant trunk technique (odds ratio 36.3), previous repair of thoracoabdominal aorta or descending aorta (odds ratio 29.4), proximal atherothrombotic aorta (odds ratio 9.6), chronic obstructive lung disease (odds ratio 7.1) and old age (odds ratio 1.1) as predictors of spinal cord injury (p < 0.0001, area under curve 0.93).

CONCLUSIONS

Spinal cord injury occurs with a non-negligible incidence following aortic arch replacement. The full objective assessment of the morphology of the whole aorta and the recognition of the risk factors are mandatory.

Endovascular treatment of complex diseases of the thoracic aorta-10 years single centre experience

BACKGROUND

Introduction of invasive endovascular techniques constituted a real a breakthrough in the treatment of aortic aneurysm dissection and rupture. We assessed the effectiveness and safety of thoracic endovascular aortic repair (TEVAR) in patients with thoracic aortic pathologies.

METHODS

Between 2007 and 2017, 118 patients with thoracic aortic pathology underwent TEVAR. Among them, 20 (16.9%) patients required hybrid procedures. Stent grafts indication were thoracic aortic aneurysm in 46 (39.0%) patients, type B dissection in 68 (57.6%) patients and other indications in 4 (3.3%). Procedural success rate, in-hospital and late mortality and morbidity were evaluated.

RESULTS

The patients were followed-up for a mean of 55 months (range, 6-118 months). The technical success rate was 96%. Five patients died during the first 30 days after procedure (mortality 4.2%), four due to ischemic stroke followed by multi-organ failure and another one hemodynamically significant type I endoleak. Most of them were noted in the first years of our study. Five others died during post-discharged period. Four patients developed neurological complications, including stroke (n=2; 1.7%) and paraparesis (n=2; 1.7%). There were 6 (5.1%) primary (5 type I and 1 type II) and 3 (2.5%) secondary endoleaks (1 type I and 2 type III). Secondary interventions were required in 8 subjects. There was one case of stent collapse and two retrograde aortic dissection.

CONCLUSIONS

Treatment of descending aortic diseases by using stent graft implantation has become the method of choice, decreasing the risk of open surgery, especially in patients with severe clinical state and comorbidities. However, effectiveness and safety may be achieved by experience team.

Impact of preservation of the latissimus dorsi muscle through a left anteroaxillary thoracotomy on spinal cord protection in descending thoracic and thoraco-abdominal aortic operations†

OBJECTIVES

The presence of collateral network circulation to the spinal cord, which is reflected in the repair of a descending thoracic aortic aneurysm (dAo) and a thoraco-abdominal aortic aneurysm (TAAo), has been demonstrated in clinical and animal experimental data. The latissimus dorsi muscle (LDM) including the thoracodorsal artery might be one of the major sources of this collateral network. The objective of this study was to evaluate the impact on spinal cord safety of a left anteroaxillary thoracotomy with minimal muscle division including preservation of the LDM in surgery for dAo and TAAo.

METHODS

Sixty-nine patients [64 (23-85) years old; 56 men] who underwent surgical repair for dAo and TAAo were divided into 2 groups: 29 [65 (23-84) years old] with an anteroaxillary thoracotomy with LDM preservation (PL group) and 40 [61 (28-85) years old] with a lateral thoracotomy without LDM preservation (NL group).

RESULTS

Aortic repairs were performed at the dAo in 30 patients including 14 in the PL group vs 16 in the NL group and at the TAAo in 39 patients including 15 in the PL group vs 24 in the NL group. There were 2 (2.9%) 30-day deaths; 2 (7.9%) in the PL group vs none in the NL group (P = 0.173). No strokes occurred. In patients with a femoro-femoral partial cardiopulmonary bypass with mild hypothermia, the incidence of loss of signal of motor-evoked potentials (>50%) was significantly lower in the PL group; 5.6% vs 31.8% (P = 0.039). The frequency of signal reduction of the remaining motor-evoked potential after surgery was also significantly lower in the PL group: 3.7% vs 25% (P = 0.040). Subsequently, the rate of spinal cord complications were lower in the PL group: 3.4% vs 12.5% (P = 0.188).

CONCLUSIONS

The left anteroaxillary thoracotomy with minimal incision of the muscles including the LDM might have potential advantages for spinal cord protection via preserved intramuscular collateral circulations to the spinal cord in dAo/TAAo open repairs.

Spinal Cord Ischemia after Endovascular Aortic Repair of a Unilateral Iliac Artery Dissecting Aneurysm: A Case Report

PURPOSE

Spinal cord ischemia (SCI) is a rare complication of endovascular repair of abdominal aortic aneurysm that is attributed to the variable anatomy of the artery of Adamkiewicz, embolization of the collateral circulation, or hypoperfusion of cord structures secondary to hypotension.

CASE REPORT

A hypertensive 83-year-old male with chronic obstructive pulmonary disease presented with a 2.3-cm right iliac artery dissecting aneurysm. Paraplegia occurred on the first day after endovascular repair of iliac artery aneurysm. Postoperative magnetic resonance imaging showed multiple foci of spinal cord ischemia involvement from T10 to L1. Neither arterial pressure augmentation nor steroid therapy was effective. We hypothesized that the compromised blood flow from the artery of Adamkiewicz, combined with the transient hypotension and embolism, resulted in spinal cord infarction. The patient was eventually transferred to a nursing facility, with no improvement in his neurological status.

CONCLUSIONS

SCI after endovascular aortic repair is an extremely rare and unpredictable complication. Physicians should pay more attention to the patients with comorbidities of atherosclerosis, chronic obstructive pulmonary disease, or peripheral artery occlusive disease.

Dexmedetomidine attenuates spinal cord ischemia-reperfusion injury through both anti-inflammation and anti-apoptosis mechanisms in rabbits

Background

Dexmedetomidine (Dex) can improve neuronal viability and protect the spinal cord from ischemia–reperfusion (I/R) injury, but the underlying mechanisms are not fully understood. This study investigated the effects of dexmedetomidine on the toll-like receptor 4 (TLR4)-mediated nuclear factor κB (NF-κB) inflammatory system and caspase-3 dependent apoptosis induced by spinal cord ischemia–reperfusion injury.

Methods

Twenty-four rabbits were divided into three groups: I/R, Dex (10 µg/kg/h prior to ischemia until reperfusion), and Sham. Abdominal aortic occlusion was carried out for 30 min in the I/R and Dex groups. Hindlimb motor function was assessed using the Tarlov scoring system for gait evaluation. Motor neuron survival and apoptosis in the ventral grey matter were assessed by haematoxylin–eosin staining and terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labelling staining. The expression and localisation of ionised calcium-binding adaptor molecule 1, TLR4, NF-κB and caspase-3 were assessed by immunoreactivity analysis. The levels of interleukin 1β and tumour necrosis factor α were assessed using enzyme-linked immunosorbent assays.

Results

Perioperative treatment with dexmedetomidine was associated with a significant preservation of locomotor function following spinal cord ischemia–reperfusion injury with increased neuronal survival in the spinal cord compared to control. In addition, dexmedetomidine suppressed microglial activation, inhibited the TLR4-mediated NF-κB signalling pathway, and inhibited the caspase-3 dependent apoptosis.

Conclusions

Dexmedetomidine confers neuroprotection against spinal cord ischemia–reperfusion injury through suppression of spinal cord inflammation and neuronal apoptosis. A reduction in microglial activation and inhibition of both the TLR4-mediated NF-κB signalling pathway and caspase-3 dependent apoptosis are implicated.

A critical appraisal of 11th century treatise by Ibn Sina (Avicenna) on the anatomy of the vascular system: Comparison with modern anatomic descriptions

Ibn Sina (also known as Avicenna in the West) was the most famous physician and medical scientist of the medieval era. His book, the Canon of Medicine comprised a vast collection of medical information ranging from basic medical sciences to specialised medical fields. Herein, we present an analysis of the cardiovascular system, particularly giving an in-depth comparison of the structural and functional anatomy of the arteries and veins of the body as described by Avicenna in the Canon of Medicine and comparing them to modern extant anatomical literature.

S-100β and Antioxidant Capacity in Cerebrospinal Fluid during and after Thoracic Endovascular Aortic Repair

Background

Thoracic Endovascular Aortic Repair (TEVAR) has substantially decreased the mortality and major complications from aortic surgery. However, neurological complications such as spinal cord ischemia may still occur after TEVAR. S-100β is a biomarker of central nervous system injury, and oxidant injury plays an important role in neurological injury. In this pilot study, we examined the trends of S-100β and antioxidant capacity in the CSF during and after TEVAR.

Methods

We recruited 10 patients who underwent elective TEVAR. CSF samples were collected through a lumbar catheter at the following time points: before the start of surgery (T0) and immediately (T1) and 24 (T2) and 48 hours (T3) after the deployment of the aortic stent. S-100β and CSF antioxidant capacity were analyzed with the use of commercially available kits.

Results

We observed that the level of S-100β in all of the subjects at 24 hours after the deployment of the aortic stent (T2) increased. However, the levels of S-100β at T1 and T3 were comparable to the baseline value. The antioxidant capacity remained unchanged. No patient had a clinical neurologic complication.

Conclusions

Our observations may indicate biochemical/subclinical central nervous system injury attributable to the deployment of the aortic stent.

Signaling pathways involved in HSP32 induction by hyperbaric oxygen in rat spinal neurons

Spinal cord injury (SCI) is a debilitating disease, effective prevention measures are in desperate need. Our previous work found that hyperbaric oxygen (HBO) preconditioning significantly protected rats from SCI after stimulated diving, and in vitro study further testified that HBO protected primary cultured rat spinal neurons from oxidative insult and oxygen glucose deprivation injury via heat shock protein (HSP) 32 induction. In this study, underlying molecular mechanisms were further investigated. The results showed that a single exposure to HBO significantly increased intracellular levels of reactive oxygen species (ROS) and nitric oxide (NO) and activated MEK1/2, ERK1/2, p38 MAPK, CREB, Bach1 and Nrf2. The induction of HSP32 by HBO was significantly reversed by pretreatment neurons with ROS scavenger N-Acetyl-L-cysteine, p38 MAPK inhibitor or Nrf2 gene knockdown, enhanced by MEK1/2 inhibitors or gene knockdown but not by ERK1/2 inhibitor. CREB knockdown did not change the expression of HSP32 induced by HBO. N-Acetyl-L-cysteine significantly inhibited the activation of MEK1/2, ERK1/2, p38 MAPK, and Nrf2. Activation of Nrf2 was significantly inhibited by p38 MAPK inhibitor and the nuclear export of Bach1 was significantly enhanced by MEK1/2 inhibitor. The results demonstrated that HBO induces HSP32 expression through a ROS/p38 MAPK/Nrf2 pathway and the MEK1/2/Bach1 pathway contributes to negative regulation in the process. More importantly, as we know, this is the first study to delineate that ERK1/2 is not the only physiological substrates of MEK1/2.

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HBO induces HSP32 through ROS/p38 MAPK/Nrf2 pathway in rat spinal neurons.

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ROS but not RNS participates in HBO induced HSP32 expression.

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MEK1/2/Bach1 contributes to negative regulation in HBO induced HSP32 expression.

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MEK1/2 acts through pathways other than ERK1/2.

Hemiarch versus total aortic arch replacement in acute type A dissection: a systematic review and meta-analysis

BACKGROUND

Despite recent advances in aortic surgery, acute type A aortic dissection remains a surgical emergency associated with high mortality and morbidity. Appropriate management is crucial to achieve satisfactory outcomes but the optimal surgical approach is controversial. The present systematic review and meta-analysis sought to access cumulative data from comparative studies between hemiarch and total aortic arch replacement in patients with acute type A aortic dissection.

METHODS

A systematic review of the literature using six databases. Eligible studies include comparative studies on hemiarch versus total arch replacement reporting short, medium and long term outcomes. A meta-analysis was performed on eligible studies reporting outcome of interest to quantify the effects of hemiarch replacement on mortality and morbidity risk compared to total arch replacement.

RESULT

Fourteen retrospective studies met the inclusion criteria and 2,221 patients were included in the final analysis. Pooled analysis showed that hemiarch replacement was associated with a lower risk of post-operative renal dialysis [risk ratio (RR) =0.72; 95% confidence interval (CI): 0.56-0.94; P=0.02; I(2)=0%]. There was no significant difference in terms of in-hospital mortality between the two groups (RR =0.84; 95% CI: 0.65-1.09; P=0.20; I(2)=0%). Cardiopulmonary bypass, aortic cross clamp and circulatory arrest times were significantly longer in total arch replacement. During follow up, no significant difference was reported from current studies between the two operative approaches in terms of aortic re-intervention and freedom from aortic reoperation.

CONCLUSIONS

Within the context of publication bias by high volume aortic centres and non-randomized data sets, there was no difference in mortality outcomes between the two groups. This analysis serves to demonstrate that for those centers doing sufficient total aortic arch activity to allow for publication, excellent and equivalent outcomes are achievable. Conclusions on differences in longer term outcome data are required. We do not, however, advocate total arch as a primary approach by all centers and surgeons irrespective of patient characteristics, but rather, a tailored approach based on surgeon and center experience and patient presentation.

Feeding Arteries of the Spinal Cord at CT Angiography before and after Thoracic Aortic Endografting

Purpose:

To study the visualization of spinal cord feeding arteries in patients with complex thoracic aortic pathology undergoing endovascular aortic repair (EVAR) using an optimized protocol for multislice computed tomographic angiography (MSCTA).

Methods:

Eighteen consecutive patients (13 men; mean age 63 years, range 45–79) with aortic type B dissections (n=5), chronic expanding aortic dissections (n=5), thoracic aortic aneurysms (n=6), or penetrating aortic ulcers (n=2) underwent 16-slice CTA before and after (mean interval 9 days) EVAR. Pulse rate and neurological status were documented. Quantitative density measurements were taken at regions of interest (ROI) in the ascending thoracic aorta and at the level of the diaphragm. Two experienced radiologists qualitatively assessed the posterior intercostal arteries (PIA; fully visible, partially visible, non-visible), dorsal branches (DB; visible/non-visible), and artery of Adamkiewicz (AKA; visible/non-visible) on multiplanar reformations and maximum intensity projection reconstructions.

Results:

MSCTA was performed successfully in 17/18 patients before and after EVAR (1 patient was excluded after EVAR owing to rising creatinine levels). Before EVAR, MSCTA revealed 197/203 PIAs within the stented area, of which 179 were fully and 18 partially visible. No significant (p=0.37) difference was noted for overall PIA detection within the stented area on post-EVAR MSCTA (185/203 PIA), although only 124 were fully and 61 partially visible. Similar results were obtained for DB visualization. The AKA were seen in 10/17 patients pre EVAR and 9/17 post EVAR. In 2 patients, the AKA was localized within the stented aortic segment. ROI analysis revealed contrast densities of 427±89 HU and 398±84 HU on pre- and post-EVAR MSCTA, respectively. No neurological events were observed.

Conclusion:

The majority of posterior intercostal arteries and dorsal branches remain open after EVAR due to retrograde perfusion. High-resolution MSCTA permits accurate pre-and post-EVAR visualization of spinal cord feeding arteries in patients with thoracic aortic pathology.

Impact of Heat Shock Protein A 12B Overexpression on Spinal Astrocyte Survival Against Oxygen-Glucose-Serum Deprivation/Restoration in Primary Cultured Astrocytes

Heat shock protein A 12B (HSPA12B) is a newly discovered member of the heat shock protein 70 family. Preclinical evidence indicates that HSPA12B helps protect the brain from ischemic injury, although its specific function remains unclear. The aim of this study is to investigate whether HSPA12B overexpression can protect astrocytes from oxygen-glucose-serum deprivation/restoration (OGD/R) injury. We analyzed the effects of HSPA12B overexpression on spinal cord ischemia-reperfusion injury and spinal astrocyte survival. After ischemia-reperfusion injury, we found that HSPA12B overexpression decreased spinal cord water content and infarct volume. MTT assay showed that HSPA12B overexpression increased astrocyte survival after OGD/R treatment. Flow cytometry results showed a marked inhibition of OGD/R-induced astrocyte apoptosis. Western blot assay showed that HSPA12B overexpression significantly increased regulatory protein B-cell lymphocyte 2 (Bcl-2) levels, whereas it decreased expression of the Bax protein, which forms a heterodimer with Bcl-2. Measurements of the level of activation of caspase-3 by Caspase-Glo®3/7 Assay kit showed that HSPA12B overexpression markedly inhibited caspase-3 activation. Notably, we demonstrated that the effects of HSPA12B on spinal astrocyte survival depended on activation of the PI3K/Akt signal pathway. These findings indicate that HSPA12B protects against spinal cord ischemia-reperfusion injury and may represent a potential treatment target.

Which type of conditioning method protects the spinal cord from the ischemia–reperfusion injury in 24 hours?

Objective

This study was designed to test the effects of different types of preconditioning and postconditioning methods on spinal cord protection following aortic clamping.

Methods

The animals (rabbits) were divided into sham-operated, ischemic preconditioning, remote ischemic preconditioning, simultaneous aortic and ischemic remote preconditioning, and ischemic postconditioning groups. After neurological evaluations, ultrastructural analysis and immunohistochemical staining for caspase-3 were evaluated after 24 h following ischemia.

Results

The neurological outcomes of the remote ischemic preconditioning (4.2 ± 0.4) and ischemic postconditioning (4.6 ± 0.8) groups were significantly improved when compared with the ischemia group (2.2 ± 04). The immunohistochemical analysis revealed that the lowest percentage of apoptosis was in-group ischemic preconditioning at 12.5 ± 30.6%. In the comparison of intracellular edema in an ultrastructural analysis, the ischemic preconditioning and ischemic postconditioning groups had significantly lower values than the ischemia group.

Conclusion

The conditioning methods attenuate ischemia–reperfusion injury for spinal cord injury. Ischemic and remote preconditioning and also postconditioning methods are simple to perform and inexpensive.

Impact of vasculature damage on the outcome of spinal cord injury: a novel collagenase-induced model may give new insights into the mechanisms involved

The deleterious effect of vasculature damage on the outcome of spinal cord injury has long been recognized, and numerous clinical studies have shown that the presence of hemorrhage into the spinal cord is directly associated with a poorer neurological outcome. Vascular damage leads to decreased blood flow to the cord and the release of potentially toxic blood-borne components. Here we consider the mechanisms that may be contributing to hemorrhage-induced damage and discuss the utility of a new model of spinal cord hemorrhage, which was urgently required as most of our current understanding has been extrapolated from intracerebral hemorrhage studies.

Mn porphyrin-based SOD mimic, MnTnHex-2-PyP(5+), and non-SOD mimic, MnTBAP(3-), suppressed rat spinal cord ischemia/reperfusion injury via NF-κB pathways

Herein we have demonstrated that both superoxide dismutase (SOD) mimic, cationic Mn(III) meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin (MnTnHex-2-PyP(5+)), and non-SOD mimic, anionic Mn(III) meso-tetrakis(4-carboxylatophenyl)porphyrin (MnTBAP(3-)), protect against oxidative stress caused by spinal cord ischemia/reperfusion via suppression of nuclear factor kappa B (NF-κB) pro-inflammatory pathways. Earlier reports showed that Mn(III) N-alkylpyridylporphyrins were able to prevent the DNA binding of NF-κB in an aqueous system, whereas MnTBAP(3-) was not. Here, for the first time, in a complex in vivo system-animal model of spinal cord injury-a similar impact of MnTBAP(3-), at a dose identical to that of MnTnHex-2-PyP(5+), was demonstrated in NF-κB downregulation. Rats were treated subcutaneously at 1.5 mg/kg starting at 30 min before ischemia/reperfusion, and then every 12 h afterward for either 48 h or 7 days. The anti-inflammatory effects of both Mn porphyrins (MnPs) were demonstrated in the spinal cord tissue at both 48 h and 7 days. The downregulation of NF-κB, a major pro-inflammatory signaling protein regulating astrocyte activation, was detected and found to correlate well with the suppression of astrogliosis (as glial fibrillary acidic protein) by both MnPs. The markers of oxidative stress, lipid peroxidation and protein carbonyl formation, were significantly reduced by MnPs. The favorable impact of both MnPs on motor neurons (Tarlov score and inclined plane test) was assessed. No major changes in glutathione peroxidase- and SOD-like activities were demonstrated, which implies that none of the MnPs acted as SOD mimic. Increasing amount of data on the reactivity of MnTBAP(3-) with reactive nitrogen species (RNS) (.NO/HNO/ONOO(-)) suggests that RNS/MnTBAP(3-)-driven modification of NF-κB protein cysteines may be involved in its therapeutic effects. This differs from the therapeutic efficacy of MnTnHex-2-PyP(5+) which presumably occurs via reactive oxygen species and relates to NF-κB thiol oxidation; the role of RNS cannot be excluded.

Anterior spinal artery syndrome: reversible paraplegia after minimally invasive spine surgery

Background Context. Percutaneous balloon kyphoplasty is an established minimally invasive technique to treat painful vertebral compression fractures, especially in the context of osteoporosis with a minor complication rate. Purpose. To describe the heparin anticoagulation treatment of paraplegia following balloon kyphoplasty. Study Design. We report the first case of an anterior spinal artery syndrome with a postoperative reversible paraplegia following a minimally invasive spine surgery (balloon kyphoplasty) without cement leakage. Methods. A 75-year-old female patient underwent balloon kyphoplasty for a fresh fracture of the first vertebra. Results. Postoperatively, the patient developed an acute anterior spinal artery syndrome with motor paraplegia of the lower extremities as well as loss of pain and temperature sensation with retained proprioception and vibratory sensation. Complete recovery occurred six hours after bolus therapy with 15.000 IU low-molecular heparin. Conclusion. Spine surgeons should consider vascular complications in patients with incomplete spinal cord syndromes after balloon kyphoplasty, not only after more invasive spine surgery. High-dose low-molecular heparin might help to reperfuse the Adamkiewicz artery.

Open surgical repair for chronic type B aortic dissection: a systematic review

BACKGROUND

The treatment of chronic type B aortic dissection (CBAD) remains complicated. Thoracic endovascular aortic repair (TEVAR) has supplanted open surgical repair (OSR) as the preferred surgical treatment for CBAD. Despite TEVAR's superior short-term results, much less is understood about its long-term outcomes. As much of the understanding of OSR originates from historical report, contemporary series, with modern surgical techniques and technologies, may present an alternative to TEVAR. The present systematic review will assess the short- and long-term outcomes of historic and contemporary series of OSR for CBAD.

METHODS

Electronic searches were performed using six databases from their inception to March 2014. Relevant studies with OSRs for chronic type B dissection were identified. Data were extracted by two independent reviewers and analyzed according to predefined clinical endpoints. Studies were sub-classified into the pre-endovascular (historic series) and endovascular era (contemporary series) depending on whether the majority of cases were performed after 1999.

RESULTS

Nineteen studies were identified for inclusion for quantitative analysis. Pooled short-term mortality was 11.1% overall, and 7.5% in the nine contemporary studies. Stroke, spinal cord ischemia, renal dysfunction, and reoperation for bleeding were 5.9%, 4.9%, 8.1%, and 8.1%, respectively, for the contemporary series. Absolute late reintervention was identified in 13.3% of patients overall, and in 11.3% of patients in the contemporary series. Aggregated survival at 1-, 3-, 5-, and 10-years of all patients were 82.1%, 74.1%, 66.3%, and 50.8%, respectively.

CONCLUSIONS

OSR for chronic type B dissection in the contemporary era offers acceptable results. Management approaches should be considered carefully, taking into account both short-term and long-term complications. More research is required to clarify specific indications for OSR and TEVAR in chronic type B dissections.

Nrf2 activation in astrocytes contributes to spinal cord ischemic tolerance induced by hyperbaric oxygen preconditioning

In this study, we investigated whether nuclear factor erythroid 2-related factor 2 (Nrf2) activation in astrocytes contributes to the neuroprotection induced by a single hyperbaric oxygen preconditioning (HBO-PC) against spinal cord ischemia/reperfusion (SCIR) injury. In vivo: At 24 h after a single HBO-PC at 2.5 atmospheres absolute for 90 min, the male ICR mice underwent SCIR injury by aortic cross-clamping surgery and observed for 48 h. HBO-PC significantly improved hindlimb motor function, reduced secondary spinal cord edema, ameliorated the reactivity of spinal motor-evoked potentials, and slowed down the process of apoptosis to exert neuroprotective effects against SCIR injury. At 12 h or 24 h after HBO-PC without aortic cross-clamping surgery, Western blot, enzyme-linked immunosorbent assay, realtime-polymerase chain reaction and double-immunofluorescence staining were used to detect the Nrf2 activity of spinal cord tissue, such as mRNA level, protein content, DNA binding activity, and the expression of downstream gene, such as glutamate-cysteine ligase, γ-glutamyltransferase, multidrug resistance protein 1, which are key proteins for intracellular glutathione synthesis and transit. The Nrf2 activity and downstream genes expression were all enhanced in normal spinal cord with HBO-PC. Glutathione content of spinal cord tissue with HBO-PC significantly increased at all time points after SCIR injury. Moreover, Nrf2 overexpression mainly occurs in astrocytes. In vitro: At 24 h after HBO-PC, the primary spinal astrocyte-neuron co-cultures from ICR mouse pups were subjected to oxygen-glucose deprivation (OGD) for 90 min to simulate the ischemia-reperfusion injury. HBO-PC significantly increased the survival rate of neurons and the glutathione content in culture medium, which was mainly released from asctrocytes. Moreover, the Nrf2 activity and downstream genes expression induced by HBO-PC were mainly enhanced in astrocytes, but not in neurons. In conclusion, our findings demonstrated that spinal cord ischemic tolerance induced by HBO-PC may be mainly related to Nrf2 activation in astrocytes.

Osthole attenuates spinal cord ischemia-reperfusion injury through mitochondrial biogenesis-independent inhibition of mitochondrial dysfunction in rats

BACKGROUND

Osthole, the main bioactive compounds isolated from the traditional Chinese medical herb broad Cnidium monnieri (L.) cusson, has been shown to exert spectrum of pharmacologic activities. The aim of this study was to investigate the potential neuroprotective effects of osthole against spinal cord ischemia-reperfusion injury in rats.

MATERIALS AND METHODS

Osthole was administrated at the concentration of 0.1, 1, 10, 50, or 200 mg/kg (intraperitoneally) 1 h before spinal cord ischemia. The effects on spinal cord injury were measured by spinal cord water content, infarct volume, hematoxylin and eosin staining, and neurologic assessment. Mitochondria were purified from injured spinal cord tissue to determine mitochondrial function.

RESULTS

We found that treatment with osthole (10 and 50 mg/kg) significantly decreased spinal cord water content and infarct volume, preserved normal motor neurons, and improved neurologic functions. These protective effects can be also observed even if the treatment was delayed to 4 h after reperfusion. Osthole treatment preserved mitochondrial membrane potential level, reduced reactive oxygen species production, increased adenosine triphosphate generation, and inhibited cytochrome c release in mitochondrial samples. Moreover, osthole increased mitochondria respiratory chain complex activities in spinal cord tissue, with no effect on mitochondrial DNA content and the expression of mitochondrial-specific transcription factors.

CONCLUSIONS

All these findings demonstrate the neuroprotective effect of osthole in spinal cord ischemia-reperfusion injury model and suggest that oshtole-induced neuroprotection was mediated by mitochondrial biogenesis-independent inhibition of mitochondrial dysfunction.

Efficacy of iloprost and montelukast combination on spinal cord ischemia/reperfusion injury in a rat model

Background

The thoracic or thoracoabdominal aortic aneurysm surgery may cause spinal cord ischemia because of aortic cross-clamping and may result in severe postoperative complications caused by spinal cord injury. Ischemia/reperfusion injury may directly or indirectly be responsible for these complications. In this study we sought to determine whether combination of iloprost and montelukast can reduce the ischemia/reperfusion injury of spinal cord in a rat model.

Methods

Medulla spinalis tissue concentrations of interleukin-6 (IL-6), myeloperoxidase (MPO) and heat shock protein 70 (HSP-70) were determined in 3 groups of Spraque Dawley rats: control group (operation with cross clamping and intraperitoneal administration of 0.9% saline, n = 7), sham group (operation without cross clamping, n = 7), and study group (operation with cross-clamping and intraperitoneal administration of iloprost (25 ng/kg) and montelukast (1 mg/kg), n = 7). The abdominal aorta was clamped for 45 minutes, with a proximal (just below the left renal artery) and a distal (just above the aortic bifurcation) clip in control and study groups. Hindlimb motor functions were evaluated at 6, 12, 24, and 48 hours using the Motor Deficit Index score. All rats were sacrificed 48 hours after the procedure and spinal cord tissue levels of myeloperoxidase, interleukin-6, and heat shock protein (HSP-70) were evaluated as markers of oxidative stress and inflammation. Histopathological analyses of spinal cord were also performed.

Results

The tissue level of HSP-70 was found to be similar among the 3 groups, however, MPO was highest and IL-6 receptor level was lowest in the control group (p = 0.007 and p = 0.005; respectively). In histopathological examination, there was no significant difference among the groups with respect to the neuronal cell degeneration, edema, or inflammation, but vascular congestion was found to be significantly more prominent in the control group than in the sham or in the study group (p = 0.05). Motor deficit index scores at 24 and 48 hours after ischemia were significantly lower in the study group than in the control group.

Conclusion

This study suggests that combined use of iloprost and montelukast may reduce ischemic damage in transient spinal cord ischemia and may provide better neurological outcome.

Post-conditioning by xenon reduces ischaemia-reperfusion injury of the spinal cord in rats

BACKGROUND

The neuroprotective effects of xenon post-conditioning following spinal cord injury remain unknown. We monitored the effect of xenon post-conditioning on the spinal cord following ischaemia-reperfusion injury and determined its mechanism of action.

METHODS

Spinal cord ischaemia was induced following balloon occlusion of the thoracic aorta in male Sprague-Dawley rats. Rats were divided into three groups (n = 30 in each group). The control group underwent ischaemia-reperfusion injury and immediately inhaled 50% (v/v) nitrogen at the time of reperfusion for 60 min continuously. The xenon-post-conditioning group underwent the same surgical procedure and immediately inhaled 50% (v/v) xenon at the time of reperfusion for 60 min continuously. The sham operation group underwent the same surgical procedure without aortic catheter occlusion and inhaled the same gas as that in control rats. Neurologic function was assessed using the Basso, Beattie, and Bresnahan score at 4, 24, and 48 h after reperfusion. Histological changes were observed using Nissl staining, the ultrastructure of the spinal cord was examined using transmission electron microscopy, and apoptosis was monitored using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling.

RESULTS

Compared with the control group, the xenon-post-conditioning group showed improved neurologic outcomes (11.3 ± 1.6 vs. 15.7 ± 3.1, respectively) and had more morphologically normal neurons (6 ± 2 vs. 12 ± 3) at 48 h after reperfusion. Moreover, apoptotic cell death in xenon-treated rats was reduced when compared with control rats (18.29 ± 3.06 vs. 27.34 ± 3.63, P < 0.05, respectively).

CONCLUSIONS

Xenon post-conditioning exerts a neuroprotective effect on the spinal cord following ischaemia-reperfusion injury via its anti-apoptotic role.

[Spinal angiography : Anatomy, technique and indications]

Spinal angiography is a diagnostic modality requiring detailed knowledge of spinal vascular anatomy. The cervical spinal cord is supplied by the vertebral arteries while segmental arteries which are preserved from fetal anatomy, supply the thoracic and lumbar regions. As spinal angiography carries the risk of paraplegia the indications have to be considered very carefully. Nevertheless, spinal angiography should be performed if there is reason to suspect a spinal vascular malformation from magnetic resonance imaging (MRI).

The effect of distal aortic pressure on spinal cord perfusion in rats

BACKGROUND

Aortic cross clamping is associated with spinal cord ischemia. This study used a rat spinal cord ischemia model to investigate the effect of distal aortic pressure on spinal cord perfusion.

MATERIALS AND METHODS

Male Sprague-Dawley rats (n=12) were divided into three groups. In group A (n=4), the aorta was not occluded. In groups B (n=4) and C (n=4), the aorta was occluded. In group B the distal aortic pressures dropped to around 20 mmHg. In group C, the distal aortic pressure was decreased to near zero. The carotid artery and tail artery were cannulated to monitor the proximal aortic pressure and the distal aortic pressure. Fluorescent microspheres were used to measure the regional blood flow in the spinal cord.

RESULTS

After aortic occlusion, blood flow to the cervical spinal cord showed no significant difference among the three groups. In groups B and C, the thoracic and lumbar spinal cord and renal blood flow decreased. No microspheres were detected in the thoracic and lumbar spinal cord of group C.

CONCLUSION

The spinal cord blood flow is dependent on the distal aortic pressure after thoracic aortic occlusion.

Simultaneous Evaluation of the Whole Aorta and Artery of Adamkiewicz by MDCT

Recent technical advancement has allowed simultaneous visualization of the artery of Adamkiewicz and whole aorta by multidetector-row-CT (MDCT). Although we could visualize the artery of Adamkiewicz in a high percentage of patients with thoracoabdominal aortic diseases, CT scanning with an adequate protocol and careful post-processing are necessary for accurate evaluation. Noninvasive evaluation of the artery of Adamkiewicz is useful in planning surgery. Preoperative evaluation of the intercostal arterial level from which the artery of Adamkiewicz originates is reportedly important for preventing postoperative spinal cord ischemia. Although, the usefulness of preoperative information on the artery of Adamkiewicz is still controversial, preoperative identification of the artery of Adamkiewicz by imaging has gradually spread since our first report, and has been included in preoperative evaluation items at many institutions, revealing its contribution to improvement in surgical results. (*English Translation of J Jpn Coll Angiol, 2004, 44: 693-699.).

Rapid ischemic preconditioning with a short reperfusion time prevents delayed paraplegia in a rabbit model

BACKGROUND

Surgery for thoracic and thoracoabdominal aortic aneurysms can be complicated by a significant incidence of neurogenic deficits due to spinal cord ischemia. In this study, we investigated whether ischemic preconditioning (IPC) improves neurologic outcome in a rabbit model.

METHODS

Forty rabbits underwent infrarenal aortic occlusion. The IPC group (n = 20) had 10 minutes of aortic occlusion to induce spinal cord ischemia, 40 minutes of reperfusion, and 30 minutes of ischemia, whereas the control group (n = 20) had only 30 minutes of ischemia. Tarlov scoring (0, paraplegia; 4, normal) was used to evaluate neurologic functions 7 days later, and spinal cord segments (L4-L6) were stained with hematoxylin and eosin for histologic evaluation.

RESULTS

Complete paraplegia (grade 0) occurred in 15 (75%) of the 20 control animals, whereas in the IPC group, 13 (65%) of 20 animals were completely normal (grade 4) (P < .05).

CONCLUSION

IPC is beneficial for protecting against neurologic damage after transient aortic occlusion in a rabbit model; however, the protective mechanisms are not clear.

Reduction of spinal cord ischemia/reperfusion injury with simvastatin in rats

BACKGROUND

Surgery of the thoracic or thoracoabdominal aorta may cause spinal cord ischemia and subsequent paraplegia. However, conventional strategies for preventing paraplegia due to spinal cord ischemia provide insufficient protection and cause additional side effects. We hypothesized that simvastatin, a drug recently shown to be neuroprotective against brain ischemia/reperfusion, would be neuroprotective in a rat spinal cord ischemia/reperfusion model.

METHODS

Rats were randomly assigned to simvastatin, vehicle, or sham-surgery (sham) groups (n = 6 per group). Simvastatin (10 mg/kg) or vehicle was administered subcutaneously once daily for 7 days before aortic balloon occlusion, and once at 24 hours after reperfusion. Spinal cord ischemia was induced by balloon inflation of a 2F Fogarty catheter in the thoracic aorta, and the proximal mean arterial blood pressure was maintained at 40 mm Hg for 12 minutes. The sham group received the same operation without inflation of the balloon. Ischemic injury was assessed by hindlimb motor function using the Motor Deficit Index score at 6 to 48 hours after ischemic reperfusion, and histological assessment of the spinal cord was performed 48 hours after reperfusion.

RESULTS

The Motor Deficit Index scores at 24 and 48 hours after reperfusion were significantly improved in the simvastatin group compared with the vehicle group (P = 0.021 and P = 0.023, respectively). Furthermore, there were significantly more normal motor neurons in the simvastatin group than in the vehicle group (P = 0.037). The percentage area of white matter vacuolation was significantly smaller in the simvastatin group than in the vehicle group (P = 0.030).

CONCLUSIONS

Simvastatin treatment can attenuate hindlimb motor dysfunction and histopathological changes in spinal cord ischemia/reperfusion injury in rats.

Redefining tissue engineering for nanomedicine in ophthalmology

Working at the nanoscale means to completely rethink how to approach engineering in the body in general and in the eye in particular. In nanomedicine, tissue engineering is the ability to influence an environment either by adding, subtracting or manipulating that environment to allow it to be more conducive for its purpose. The goal is to function at the optimum state, or to return to that optimum state. Additive tissue engineering replaces cells or tissue, or tries to get something to grow that is no longer there. Arrestive tissue engineering tries to stop aberrant growth which, if left uncontrolled, would result in a decrease in function. Nano delivery of therapeutics can perform both additive and arrestive functions influencing the environment either way, depending on the targeting. By manipulating the environment at the nanoscale, the rate and distribution of healing can be controlled. It infers that potential applications of nanomedicine in ophthalmology include procedures, such as corneal endothelial cell transplantation, single retinal ganglion cell repair, check of retinal ganglion cell viability, building of nanofibre scaffolds, such as self-assembling peptides, to create a scaffold-like tissue-bridging structure to provide a framework for axonal regeneration in the case of optic nerve reconnection or eye transplantation, and ocular drug delivery. Examples of potential arrestive therapies include gene-related treatment modalities to inhibit intraocular neovascularization and to block retinal cell apoptosis. Looking towards the future, this review focuses on how nanoscale tissue engineering can be and is being used to influence that local environment.

Does interruption of the artery of Adamkiewicz during total en bloc spondylectomy affect neurologic function?

STUDY DESIGN

A retrospective review of patients with interruption of the artery of Adamkiewicz during total en bloc spondylectomy (TES).

OBJECTIVE

To assess neurologic function after interruption of the artery of Adamkiewicz in TES.

SUMMARY OF BACKGROUND DATA

The most important feeding artery of the thoracolumbar spinal cord is the great anterior radiculomedullary artery, also called the artery of Adamkiewicz. The artery of Adamkiewicz supplies the lower two-thirds of the spinal cord via the anterior spinal artery. It is naturally believed among spine surgeons that interruption of the artery of Adamkiewicz during surgeries is absolutely contraindicated. However, it is necessary to sacrifice the artery of Adamkiewicz during TES, when the tumor, by chance, exists at the level of the artery of Adamkiewicz.

METHODS

Between 1990 and 2009, we have performed 180 cases of TES. All cases except for few emergency cases received preoperative embolization. The artery of Adamkiewicz was verified by angiography of the segmental arteries. There were 15 patients in which the artery of Adamkiewicz was found at the levels of resected vertebrae. Interruption of the artery was performed during surgery in these 15 cases. Neurologic function was analyzed retrospectively.

RESULTS

Of the 15 patients, the Frankel grade before surgery was C in 1, D in 5, and E in 9. At follow-up, the Frankel grade was D in 1 and E in 14. There were no cases of neurologic deterioration or paralysis after TES.

CONCLUSION

On the basis of our results of TES on up to 3 vertebrae, interruption of the artery of Adamkiewicz for TES does not adversely affect neurologic function. We advocate strongly that our surgeons are allowed to sacrifice up to 3 pairs of segmental arteries, even including the artery of Adamkiewicz, if necessary.

Excessively high systemic blood pressure in the early phase of reperfusion exacerbates early-onset paraplegia in rabbit aortic surgery

OBJECTIVE

We have demonstrated that therapeutic augmentation of systemic blood pressure during spinal cord ischemia plays an important role in minimizing spinal cord injury in both experimental and clinical aortic surgery. However, there remain concerns that excessively high blood pressure during spinal cord reperfusion may aggravate the reperfusion injury. The purpose of this study is to investigate the effect of high blood pressure during spinal cord reperfusion on postoperative neurologic outcomes after aortic surgery in rabbits.

METHODS

Experiments were performed using a rabbit spinal cord ischemia-reperfusion model in 2 randomly divided groups: (1) In the HR group, the mean blood pressure was maintained at a high level (121 +/- 1.3 mm Hg) during reperfusion with intravenously administered phenylephrine; and (2) in the CR group, the mean blood pressure was not medically controlled (75 +/- 9.1 mm Hg) during reperfusion. Neurologic and histologic assessments and evaluation of early reperfusion injury were performed.

RESULTS

In the HR group, slow and incomplete recovery of transcranial motor-evoked potentials (P = .02) and low neurologic scores (P < .005) were observed during spinal cord reperfusion compared with the CR group. At 48 hours of reperfusion, there were significantly fewer viable neuron cells, more apoptosis, and more perivascular edema with gray matter vacuolation in the HR group (P < .001 for each). At 3 hours, myeloperoxidase activity (P = .0021), vascular permeability (P = .0012), and superoxide generation (P < .0001) were significantly increased in the HR group.

CONCLUSION

Excessively high blood pressure in the early phase of spinal cord reperfusion increased reperfusion injury in the spinal cord, leading to exacerbation of early-onset paraplegia. Avoidance of spinal cord reperfusion with high blood pressure may be one management strategy in thoracoabdominal aortic surgery.