Prevention of postoperative paraplegia during thoracoabdominal aortic surgery1This article has been selected for the open discussion forum on the CTSNet Web site: http://www.ctsnet.org/discuss1

Patterns of collateral arteries to the spinal cord after thoraco-abdominal aortic aneurysm repair

OBJECTIVES

Our goal was to evaluate postoperative patterns of collateral arteries to the spinal cord during occlusion of the segmental arteries supplying the artery of Adamkiewicz (AKA).

METHODS

Between April 2011 and December 2022, a total of 179 patients underwent thoraco-abdominal aortic aneurysm repair; 141 had an identifiable AKA on preoperative multidetector computed tomography scans, 40 underwent thoraco-abdominal aortic aneurysm replacement (TAAR) and 101 underwent thoracic endovascular aortic repair (TEVAR). New postoperative collateral blood pathways invisible on preoperative contrast-enhanced computed tomography scans were identified in 42 patients (10 patients who had TAAR vs 32 patients who had TEVAR) who underwent preoperative and postoperative multidetector computed tomography scanning for AKA identification.

RESULTS

The thoracodorsal and segmental arteries were the main collateral pathways in both groups. Th9-initiated collaterals were the most common. Collaterals from the internal thoracic artery were observed in the TEVAR group but not in the TAAR group. One patient in the TEVAR group experienced postoperative paraparesis, which was not observed in the TAAR group. Postoperative paraplegia was more common in the non-Th9-origin group, but this difference was not significant.

CONCLUSIONS

Thoracodorsal and segmental arteries may be important collateral pathways after TEVAR and TAAR. For thoracodorsal arteries, preserving the thoracodorsal muscle during the approach would be crucial; for segmental arteries, minimizing the area to be replaced or covered would be paramount. An AKA not initiated at the Th9 level poses a high risk of postoperative paraplegia.

Regionally infused lidocaine can dose-dependently protect the ischemic spinal cord in rabbits and may be associated with the EAA changes

OBJECTIVE

In our previous study, we found that lidocaine, infused through the abdominal aorta, could protect the spinal cord against the ischemia-reperfusion (I/R) injury caused by aortic occlusion. However, whether lidocaine protective effects have dose-dependent properties and its underlying mechanisms still remain unclear. This study was designed to investigate whether regionally infused lidocaine could dose-dependently protect spinal cord against I/R injury in rabbits and its underlying mechanism.

METHODS

46 New Zealand white rabbits were randomized into six groups: Group NS (normal saline control); Group L10 (lidocaine 10 mg/kg); Group L20 (lidocaine 20 mg/kg); Group L40 (lidocaine 40 mg/kg); Group L80 (lidocaine 80 mg/kg) and Group Sham. In Group NS, Group L10, Group L20, Group L40 and Group L80, spinal cord ischemia was induced by infrarenal aortic occlusion for 30 min. The sham group did not receive spinal cord ischemia. During the occlusion, normal saline or lidocaine at different doses was infused continuously through a catheter into the clamped abdominal aorta respectively. Neurologic behavior functions were assessed according to the Tarlov scale system at the moments of 0, 6, 24 and 48 h after reperfusion. The neural injuries were evaluated by the histological examination and the count of normal α-motor neurons in the ventral horn. The levels of excitatory amino acids (EAAs) in the spinal cord, including glutamate (Glu) and aspartic acid (Asp), were analyzed by high performance liquid chromatography with fluorescence detection.

RESULTS

The Tarlov scales in the Group L20 and the Group L40 were significantly higher than those in the Group NS at 24 and 48 h after reperfusion (P < 0.05). 12.5 % animals in Group L40 and 25 % animals in Group L20 were paraplegic versus 75 % animals in Group NS at 48 h after reperfusion (P < 0.05). The median of normal α-motor neurons in the L20, L40 and L80 groups was 7.5, 9 and 5 respectively which was significantly higher than in the NS group (count 0, P < 0.05). The levels of L-ASP and L-Glu remarkably decreased in the Group L10 and the Group L40 compared to Group NS (P < 0.05).

CONCLUSIONS

These data revealed that regional administration of lidocaine through the abdominal aorta can provide dose-dependent protection on spinal cord I/R in rabbits. Inhibition of EAA release may be one of the underlying mechanisms.

Direct Monitoring of Reconstructed Segmental Arterial Pressure during Deep Hypothermic Thoracoabdominal Aortic Aneurysm Surgery

Deep hypothermia in thoracoabdominal aortic aneurysm operations is considered extremely useful for ensuring sufficient time to reconstruct the segmental arteries feeding the spinal cord. However, because the amplitude of motor evoked potentials (MEPs) decrease or disappear during deep hypothermia, feasible methods for assessing spinal cord circulation have not yet been reported. Performing additional segmental arterial reconstructions that rely on MEPs is also impractical. In the present case, to ascertain spinal cord circulation under deep hypothermia, we intraoperatively measured the reconstructed segmental arterial pressure in real time and investigated whether sufficient spinal cord blood flow had been attained.

Transapical aortic perfusion using a deep hypothermic procedure during descending thoracic or thoracoabdominal aortic surgery

BACKGROUND

In descending thoracic aortic aneurysm (DTAA) or thoracoabdominal aortic aneurysm (TAAA) surgery, though proximal anastomosis using deep hypothermic circulatory arrest (DHCA) is often selected, there are issues surrounding brain and heart protection. In this study, the usefulness of concomitant upper body perfusion via transapical aortic cannulation during deep hypothermic surgery was examined.

METHODS

Between October 2014 and May 2019, 5 patients (Crawford extent II chronic dissection, N.=3; extent IV aneurysms, N.=1; DTAA, N.=1) underwent DTAA/TAAA repair under deep hypothermia using transapical aortic perfusion. A proximal anastomosis and artery of Adamkiewicz (AKA) reconstruction were performed under continuous perfusion of the upper and lower body at 20 °C.

RESULTS

The time from aortic cross-clamping to proximal anastomosis was 69±33 minutes, and it took 86±47 minutes to AKA reperfusion. There was no spinal cord ischemic injury or brain or heart complications. One patient required tracheostomy, and the average postoperative intubation time for the other patients was 57±52 hours. All patients were discharged, and the average postoperative hospital stay was 25.6±8.1 days.

CONCLUSIONS

Concomitant upper body perfusion by the transapical aortic approach contributes to avoidance of brain and heart complications and maintaining spinal cord circulation under deep hypothermic DTAA/TAAA surgery.

Hypoxic preconditioning increases the protective effect of bone marrow mesenchymal stem cells on spinal cord ischemia/reperfusion injury

Transplantation of bone marrow mesenchymal stem cells (BMSCs) protect against spinal cord ischemia/reperfusion injury (SCIRI). However, a large number of transplanted BMSCs often undergo apoptosis, which severely affects the treatment outcome. Previous studies have demonstrated that hypoxic preconditioning effectively increases the survival rate of BMSCs following transplantation, and increases their protective effect on injured tissues. However, there have been few reports regarding roles of hypoxic preconditioning in SCIRI. The present study isolated rat BMSCs and separately transplanted hypoxia‑ and non‑hypoxia‑preconditioned BMSCs into the spinal cord tissues of rats with SCIRI. The role of hypoxic preconditioning in the promotion of the protective effect of BMSCs on SCIRI was investigated using neurological function scores, Evans blue staining, hematoxylin and eosin staining and terminal deoxynucleotidyl transferase dUTP nick end labeling. In addition, reverse transcription‑quantitative polymerase chain reaction and western blotting were used to detect the expression levels of hypoxia‑inducible factor 1α (HIF‑1α), and to investigate its possible underlying mechanism of action. The results indicated that hypoxic preconditioning effectively increased the protective effects of BMSCs on neurological function, blood spinal cord barrier and tissue damage following SCIRI, and inhibited apoptosis. Furthermore, hypoxic preconditioned BMSCs upregulated the expression of HIF‑1α in spinal cord tissues. Therefore, hypoxic preconditioning effectively increased the protective effect of BMSCs on SCIRI and may be associated with upregulation of the expression of HIF‑1α. Hypoxic preconditioning may serve as an effective means of increasing the protective effect of BMSCs on SCIRI.

Effects of adenosine monophosphate-activated kinase in the ventral horn of rabbit spinal cord after transient ischemia

OBJECTIVE

To investigate the effect compound C, an adenosine monophosphate-activated kinase (AMPK) inhibitor, has on motor neurons of rabbit spinal cord after ischemia/reperfusion.

DESIGN

Compound C (30 mg/kg) was administered intraperitoneally to rabbits 30 minutes before ischemia and the animals were sacrificed at 15 minutes after ischemia/reperfusion to measure lactate levels and at 72 hours after ischemia/reperfusion for morphological study.

RESULTS

The administration of compound C did not produce any significant changes in physiological parameters such as pH, arterial blood gas (PaCO(2) and PaO(2)), and blood glucose in rabbit either at 10 minutes before ischemia or at 10 minutes after reperfusion. However, the administration of compound C did significantly ameliorate lactate acidosis at 15 minutes after reperfusion. In addition, the administration of compound C significantly improved the neurological scores of the rabbits and reduced the neuronal death seen in the ventral horn of their spinal cords at 72 hours after ischemia/reperfusion.

CONCLUSIONS

Inhibition of AMPK can ameliorate the ischemia-induced neuronal death in the spinal cord via the reduction of early lactate acidosis.

Spinal cord injury following thoracic and thoracoabdominal aortic repairs

Objective

To discuss the currently available approaches to prevent spinal cord injury during thoracic and thoracoabdominal aortic repairs.

Methods

We carried out a PubMed search up to 2013 using the Medical Subject Headings: “aortic aneurysm/surgery” and “spinal cord ischemia”; “aortic aneurysm, thoracic/surgery” and “spinal cord ischemia”; “aneurysm/surgery” and “spinal cord ischemia/cerebrospinal fluid”; “aortic aneurysm/surgery” and “paraplegia”. All 190 original articles satisfying our inclusion criteria were analyzed for incidence, predictors, and other pertinent variables related to spinal cord injury, and we compared the results in recent publications with those in earlier reports.

Results

The mean age of the 38,491 patients was 65.3 ± 4.9 years. The overall incidence of paraplegia and/or paraparesis was 7.1% ± 6.1% (range 0%–32%). The incidence of spinal cord injury before 2000, from 2001 to 2007, and 2008–2013 was 9.0% ± 6.7%, 7.0% ± 6.1%, and 5.9% ± 5.2%, respectively ( p = 0.019). Various predictors of spinal cord injury were identified, extent of disease being the most common. Modification of surgical techniques, use of adjuncts, and better understanding of spinal cord perfusion physiology were attributed to the decrease in postoperative spinal cord injury in recent years.

Conclusions

Spinal cord injury after thoracic and thoracoabdominal aortic repair poses a real challenge to cardiovascular surgeons. However, with evolving surgical strategies, identification of predictors, and use of various adjuncts over the years, the incidence of spinal cord injury after thoracic/thoracoabdominal aortic repair has declined. Embracing a multimodality approach offers a good insight into combating this grave complication.

Minimally Invasive Segmental Artery Coil Embolization for Preconditioning of the Spinal Cord Collateral Network before One-Stage Descending and Thoracoabdominal Aneurysm Repair

Objective

Paraplegia remains the most devastating complication after thoracic and thoracoabdominal aortic aneurysm (TAA/A) repair. The collateral network (CN) concept of spinal cord perfusion suggests segmental artery (SA) occlusion to mobilize redundant intraspinal and paraspinal arterial sources and ultimately trigger arteriogenesis, leading to spinal cord blood flow restoration within 96 to 120 hours. This principle is used by the two-staged approach to TAA/A-repair—which has lead to an elimination of paraplegia in an experimental model. However, the clinical implementation of a two-staged surgical procedure is challenging, particularly in the absence of an appropriate vascular segment for a “staged” open anastomosis or an appropriate endovascular landing zone. Selective, transfemoral minimally invasive SA coil embolization (MISACE) could provide the solution for one-stage repair of extensive aortic pathologies by triggering arteriogenic CN preconditioning and thereby allowing for recruitment of otherwise redundant arterial collaterals to the spinal cord.

Methods

The feasibility of MISACE was explored in a single animal using an established piglet model. A 6F sheet was introduced via the femoral artery, and a 4F standard Judkins catheter was used for selective angiography and coil insertion. All thoracic and lumbar aortic SAs (15 pairs; Th4–L5) were successfully identified by dye injection. Pediatric platinum endovascular coils (Trufill Pushable Coils, 3 × 20 mm; Cordis, Waterloo, Belgium) were deployed to serially occlude the SA mimicking a CN preconditioning procedure.

Results

All intercostal (thoracic) and lumbar aortic SAs (Th4–L5) were successfully identified and occluded by coil embolization. Successful SA coil embolization was verified intraoperatively by selective dye injection on angiography. No intraoperative coil dislodgement occurred. Autopsy revealed complete occlusion of all embolized SAs enhanced by early local thrombus formation. Thrombotic material was found only distally to the coils. No SA dissection was observed at the aortic SA origins.

Conclusions

The MIS ACE technique allows for rapid serial endovascular occlusion of all thoracic and lumbar SAs. This new innovative approach bares the potential to CN preconditioning at the respective level of aortic pathology—to allow for adequate perioperative spinal cord blood supply—before conventional open or endovascular surgery. Selective, transarterial MISACE might lead to a dramatic reduction of ischemic spinal cord injury after open and endovascular TAA/A repair in the future.

Ischemic preconditioning protects against spinal cord ischemia-reperfusion injury in rabbits by attenuating blood spinal cord barrier disruption

Ischemic preconditioning has been reported to protect against spinal cord ischemia-reperfusion (I-R) injury, but the underlying mechanisms are not fully understood. To investigate this, Japanese white rabbits underwent I-R (30 min aortic occlusion followed by reperfusion), ischemic preconditioning (three cycles of 5 min aortic occlusion plus 5 min reperfusion) followed by I-R, or sham surgery. At 4 and 24 h following reperfusion, neurological function was assessed using Tarlov scores, blood spinal cord barrier permeability was measured by Evan’s Blue extravasation, spinal cord edema was evaluated using the wet-dry method, and spinal cord expression of zonula occluden-1 (ZO-1), matrix metalloproteinase-9 (MMP-9), and tumor necrosis factor-α (TNF-α) were measured by Western blot and a real-time polymerase chain reaction. ZO-1 was also assessed using immunofluorescence. Spinal cord I-R injury reduced neurologic scores, and ischemic preconditioning treatment ameliorated this effect. Ischemic preconditioning inhibited I-R-induced increases in blood spinal cord barrier permeability and water content, increased ZO-1 mRNA and protein expression, and reduced MMP-9 and TNF-α mRNA and protein expression. These findings suggest that ischemic preconditioning attenuates the increase in blood spinal cord barrier permeability due to spinal cord I-R injury by preservation of tight junction protein ZO-1 and reducing MMP-9 and TNF-α expression.

Beneficial effects of hydrogen-rich saline against spinal cord ischemia-reperfusion injury in rabbits

Hydrogen-rich saline (HS) is reported to be a new therapeutic agent in ischemia-reperfusion (I/R)-induced organ damage. The present study was designed to investigate the beneficial effects of HS against spinal cord I/R injury and its associated mechanisms. Spinal cord ischemia was induced by infrarenal aortic occlusion for 20min in male New Zealand white rabbits. Different doses of HS were intravenously (i.v.) administered at 5min before or after the beginning of reperfusion. Moreover, the roles of mitochondrial ATP-sensitive potassium channels (mitoKATP), oxidative stress, inflammatory cytokines and apoptosis was assessed. Here, we found that I/R-challenged rabbits exhibited significant spinal cord injury characterized by the decreased numbers of normal motor neurons and hind-limb motor dysfunction, which was significantly ameliorated by 5mL/kg and 10mL/kg HS treatment before reperfusion or 10mL/kg HS treatment after reperfusion. However, the protective effects of HS treatment in spinal cord I/R injury were partially abolished by the selective mitoKATP channel blocker 5-hydroxydecanoate (5-HD). Moreover, we showed that the beneficial effects of 10mL/kg HS treatment against spinal cord I/R damage were associated with the decreased levels of oxidative products [8-iso-prostaglandin F2α (8-iso-PGF2α) and malondialdehyde (MDA)] and pro-inflammatory cytokines [tumor necrosis factor-alpha (TNF-α) and high-mobility group box 1 (HMGB1)], as well as the increased activities of antioxidant enzymes [superoxide dismutase (SOD) and catalase (CAT)] in serum at 6h, 12h, 24h, 48h and 72h after reperfusion and in spinal cord at 72h after reperfusion. Furthermore, HS treatment (10mL/kg) reduced caspase-3 activity in the spinal cord of this model. Thus, HS may be an effective therapeutic agent for spinal cord I/R injury via activation of mitoKATP channels as well as reduction of oxidative stress, inflammatory cytokines and apoptosis.

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.

Neuroprotective effects of adipose-derived stem cells against ischemic neuronal damage in the rabbit spinal cord

Transplantation of adipose-derived stem cells (ASCs) is one of the possible therapeutic tools for ischemic damage. In this study, we observed the effects of ASCs against ischemic damage in the ventral horn of L(5-6) levels in the rabbit spinal cord. ASCs were isolated from rabbits, and cell type was confirmed by flow cytometry analysis, labeling with CM-DiI dye and differentiation into adipocytes in adipogenesis differentiation medium. ASCs were administered intrathecally into recipient rabbits (2 × 10⁵) immediately after reperfusion following a 15-min aortic artery occlusion in the subrenal region. Transplantation of ASCs significantly improved functions of the hindlimb and morphology of the ventral horn of spinal cord although CM-DiI-labeled ASCs were not observed in the spinal cord parenchyma. In addition, transplantation of ASCs significantly increased brain-derived neurotrophic factor (BDNF) levels at 72h after ischemia/reperfusion. These results suggest that transplantation of ASCs prevents motor neurons from spinal ischemic damage and reactive gliosis by increasing neurotrophic factors such as BDNF in the spinal cord.

Panax notoginsenoside produces neuroprotective effects in rat model of acute spinal cord ischemia-reperfusion injury

ETHNOPHARMACOLOGICAL RELEVANCE

Acute spinal cord ischemia-reperfusion injury (SCII) is associated with pathological changes, including inflammation, edema, and neuronal apoptosis. Panax notoginsenoside (PNS), an important traditional Chinese medicine, has shown a variety of beneficial effects, including homeostasis maintenance, anti-myocardial ischemia activities, and neuroprotective functions. However, whether it can produce neuroprotective effects in SCII and the underlying mechanisms remain largely elusive.

AIM OF THE STUDY

In the present study, we investigated the effects of PNS on neurological and histopathological changes after SCII as well as the underlying mechanisms.

MATERIALS AND METHODS

Sixty-four adult rats were randomly assigned into one of the four groups: the sham group, the ischemic group, the PNS group, and the Methylprednisolone group. A rat model of SCII was adopted from a commonly used protocol that was initially proposed by Zivin. Neurological function was evaluated with the Basso, Beattie and Bresnahan (BBB) locomotor rating scale. Histopathological changes were examined with hematoxylin and eosin staining as well as Nissl staining. Immunohistochemistry and Western blot were conducted to compare the changes in tumor necrosis factor-α, interleukin-1β, interleukin-10, aquaporin-4 (AQP-4), member 6 of the TNF receptor superfamily (Fas), and Fas ligand (FasL) in the spinal cord. Finally, neuronal apoptosis was measured by electron microscopy.

RESULTS

The BBB scores of the PNS-treated injured animals were significantly increased. The gross histopathological examination showed restored neuronal morphology and increased number of neurons after the PNS treatment. The PNS treatment decreased SCII-induced up-regulation of cytokine levels. In addition, PNS suppressed the increased expression of AQP-4 after SCII, suggesting an anti-edema effect. Finally, PNS treatment inhibited injury-induced apoptosis and reduced the expression levels of apoptosis-related proteins, Fas and FasL, confirming its anti-apoptosis effects against SCII.

CONCLUSION

The current findings suggest that PNS produces robust neuroprotective effects in spinal cord ischemia-reperfusion injury, and this role may be mediated by its anti-inflammation, anti-edema, and anti-apoptosis actions.

Neuroprotective effects of PEP-1-Cu,Zn-SOD against ischemic neuronal damage in the rabbit spinal cord

A rabbit model of spinal cord ischemia has been introduced as a good model to investigate the pathophysiology of ischemia-reperfusion (I-R)-induced paraplegia. In the present study, we observed the effects of Cu,Zn-superoxide dismutase (SOD1) against ischemic damage in the ventral horn of L(5-6) levels in the rabbit spinal cord. For this study, the expression vector PEP-1 was constructed, and this vector was fused with SOD1 to create a PEP-1-SOD1 fusion protein that easily penetrated the blood-brain barrier. Spinal cord ischemia was induced by transient occlusion of the abdominal aorta for 15 min. PEP-1-SOD1 (0.5 mg/kg) was intraperitoneally administered to rabbits 30 min before ischemic surgery. The administration of PEP-1-SOD1 significantly improved neurological scores compared to those in the PEP-1 (vehicle)-treated ischemia group. Also, in this group, the number of cresyl violet-positive cells at 72 h after I-R was much higher than that in the vehicle-treated ischemia group. Malondialdehyde levels were significantly decreased in the ischemic spinal cord of the PEP-1-SOD1-treated ischemia group compared to those in the vehicle-treated ischemia group. In contrast, the administration of PEP-1-SOD1 significantly ameliorated the ischemia-induced reduction of SOD and catalase levels in the ischemic spinal cord. These results suggest that PEP-1-SOD1 protects neurons from spinal ischemic damage by decreasing lipid peroxidation and maintaining SOD and catalase levels in the ischemic rabbit spinal cord.

Beneficial effects of hydrogen gas against spinal cord ischemia-reperfusion injury in rabbits

Recently, hydrogen gas (H₂) is reported to be a new therapeutic agent in organ damage induced by ischemia-reperfusion (I/R). The present study was designed to investigate the beneficial effects of H₂ against spinal cord I/R injury and its associated mechanisms. Spinal cord ischemia was induced by infrarenal aortic occlusion for 20 min in male New Zealand white rabbits. Treatment with 1%, 2% or 4% H₂ inhalation was given from 10 min before reperfusion to 60 min after reperfusion (total 70 min). Here, we found that I/R-challenged animals showed significant spinal cord damage characterized by the decreased numbers of normal motor neurons and hind-limb motor dysfunction, which was significantly improved by 2% and 4 % H₂ treatment. Furthermore, we found that the beneficial effects of H₂ treatment against spinal cord I/R injury were associated with the decreased levels of oxidative products [8-iso-prostaglandin F2α (8-iso-PGF2α) and malondialdehyde (MDA)] and pro-inflammatory cytokines [tumor necrosis factor-alpha (TNF-α) and high-mobility group box 1 (HMGB1)], as well as increased activities of antioxidant enzymes [superoxide dismutase (SOD) and catalase (CAT)] in serum and spinal cord. In addition, H₂ treatment reduced motor neuron apoptosis in the spinal cord of this model. Thus, H₂ inhalation may be an effective therapeutic strategy for spinal cord I/R damage.

Citicoline and postconditioning provides neuroprotection in a rat model of ischemic spinal cord injury

BACKGROUND

Ischemic spinal cord injury is a chain of events caused by the reduction and/or cessation of spinal cord blood flow, which results in neuronal degeneration and loss. Ischemic postconditioning is defined as a series of intermittent interruptions of blood flow in the early phase of reperfusion and has been shown to reduce the infarct size in cerebral ischemia. Our study aimed to characterize the relationship between the neuronal injury-decreasing effects of citicoline and ischemic postconditioning, which were proven to be effective against the apoptotic process.

METHOD

Spinal cord ischemia was produced in rats using an intrathoracic approach to implement the synchronous arcus aorta and subclavian artery clipping method. In our study, 42 male Sprague-Dawley rats (309 +/- 27 g) were used. Animals were divided into sham operated, spinal ischemia, citicoline, postconditioning, and postconditioning citicoline groups. Postconditioning was generated by six cycles of 1 min occlusion/5 min reperfusion. A 600 mmol/kg dose of citicoline was given intraperitoneally before ischemia in the citicoline and postconditioning citicoline groups. All rats were sacrificed 96 h after reperfusion. For immunohistochemical analysis, bcl-2, caspase 3, caspase 9, and bax immune staining were performed. Caspase 3, caspase 9, bax, and bcl-2 were used as apoptotic and antiapoptotic markers, respectively.

FINDINGS

The blood pressure values obtained at the onset of reperfusion were significantly lower than the preischemic values. A difference in immunohistochemical scoring was detected between the caspase 3, caspase 9, bax, and bcl-2 groups. When comparisons between the ischemia (groups 2, 3, 4, and 5) and sham groups (group 1) were performed, a significant increase in caspase 3, caspase 9, bax, and bcl-2 was detected. When comparing the subgroups, the average score of caspase 9 was found to be significantly higher in ischemia group 2. The average score of bcl-2 was also found to be significantly higher in postconditioning and citicoline group 5.

CONCLUSIONS

It is thus thought that combining citicoline with postconditioning provides protection by inhibiting the caspase pathway and by increasing the antiapoptotic proteins.

Cyclosporin A Has a Protective Effect with Induced Upregulation of Hsp70 and nNOS on Severe Spinal Cord Ischemic Injury in Rabbits

The purpose of this study is to ascertain the neuroprotective effect of cyclosporin A on the 25-min surgical ischemia model in the spinal cords of rabbits with neuropathological correlation and histoimmunochemical analyses measuring HSP70 and neuronal NOS (nNOS). New Zealand white rabbits were randomly divided into four groups (each n = 8): the C2, C7, Cs2, and Cs7 groups. The C2 and C7 groups underwent a 25-min surgical aortic cross-clamp without intervention and were sacrificed respectively on day 2 and on day 7 postoperatively. The Cs2 and Cs7 groups received cyclosporin A (25 mg/kg) intravenously 15 min after the 25-min cross-clamp and were sacrificed respectively on day 2 and day 7 postoperatively. Neurologic functions were evaluated on postoperative days 2 and 7 using the Tarlov scoring system. Then the rabbits were sacrificed for histopathologic observation. HSP 70 and nNOS stains with TUNEL assay were done for the C2 and Cs2 groups. All rabbits survived the experimental procedure. Tarlov's score for the Cs7 group (2.75 +/- 0.89) was significantly higher than that of the C7 group (1.25 +/- 1.39) (p < .05). Tarlov's score of the Cs7 group was also statistically higher on day 7 than on day 2 (p < .05). Strong correlation between the neurological and histological scorings was found. The TUNEL assay showed that the mean number of positive cells in the C2 group was 17.5 +/- 22.6 and in the Cs2 group was 12.5 +/- 11.1, but there was no statistically significant difference between the groups. There was more expression of HSP70 and nNOS in the cyclosporin groups than in the ischemia groups. In conclusion, this study demonstrates that cyclosporin A reduces neurological injury in the rabbit model of 25-min spinal cord ischemia. The neuroprotective effect of cyclosporin A against ischemia seems to be related to overexpressions of nNOS and HSP70.

Contemporary Analysis of Descending Thoracic and Thoracoabdominal Aneurysm Repair

Background— Endovascular repair of thoracic aneurysm has demonstrated low risks of mortality and spinal cord ischemia (SCI), but few large series have been published on endovascular thoracoabdominal aneurysm repair, and reports suffer from a lack of accurate comparison with similar open surgical procedures.

Methods and Results— A consecutive cohort of patients with thoracic and thoracoabdominal aneurysms treated electively with endovascular repair (ER) or surgical repair (SR) techniques between 2001 and 2006 were analyzed. The association between repair technique and SCI was evaluated with univariable analysis. Adjustments for potential confounders and for the propensity to receive ER or SR were also performed in multivariable analysis. A total of 724 patients (352 ER, 372 SR) underwent repair. The mean age was 67 years, and 65% were male. ER patients were on average 9 years older ( P <0.001), had more comorbid conditions, and more frequently had prior distal repair ( P <0.001) or underwent a type I or IV repair. SR patients more commonly had chronic dissection or required type II or type III repairs ( P <0.001). Mortality at 30 days (5.7% ER versus 8.3% SR, P =0.2) and 12 months (15.6% ER versus 15.9% SR, P =0.9) was similar. A borderline difference in SCI was found between repair techniques: 4.3% of ER and 7.5% of SR patients ( P =0.08) had SCI. In patients with ER, prior distal aortic operation was associated with the development of SCI in univariable analysis (odds ratio 4.1, 95% confidence interval 1.4 to 11.7). Multivariable analysis showed that the type of required repair (type I, II, III, or IV) was the primary factor associated with the development of SCI in ER and SR patients.

Conclusion— No significant difference in the incidence of mortality or SCI was found between ER and SR techniques. The strongest factor associated with SCI remains the extent of the disease. Further studies are indicated to compare ER with patients considered eligible for SR.

Spinal cord ischemia may be reduced via a novel technique of intercostal artery revascularization during open thoracoabdominal aneurysm repair

OBJECTIVE

To describe a novel technique for maximal reimplantation of intercostal arteries during thoracoabdominal aortic aneurysm repair.

METHODS

Eight patients underwent thoracoabdominal aortic aneurysm (TAAA) repair with this new technique from 2005 to 2006. Follow-up ranged from 6 to 14 months. All patients had a previous type B dissection with subsequent aneurysmal degeneration into an extent I TAAA. Aneurysm repair was performed through a thoracoabdominal incision and circulatory arrest in seven and left atrial-left femoral (LA-FA) bypass in one. The grafts extended from the distal arch at the subclavian artery to the visceral and renal arteries. An 8 mm graft was then extended from the proximal to the distal graft with a spatulation of the graft allowing a side-to-side anastomosis of the graft to the posterior aortic wall incorporating multiple pairs of intercostal arteries. Intraoperative electroencephalogram (EEG) and somatosensory evoked potentials (SSEP) were monitored during each operation.

RESULTS

All patients were ambulatory at the time of admission. One patient had suffered a previous spinal cord infarction from the original dissection and had residual unilateral leg weakness prior to the TAAA repair. There was an average of seven pairs of patent intercostal arteries upon opening the aorta. We reimplanted an average of five pairs of vessels. There were no perioperative complications. No patients sustained transient or permanent paraplegia in the postoperative or follow-up period. The one patient with preoperative leg weakness had reported subjective increased strength in the affected leg after the operation. In four cases, normalization of SSEP waveforms did not occur until after reimplantation of the intercostal arteries despite full return of EEG waveforms, restoration of lower extremity perfusion, and rewarming of the patient. Follow-up CT scan angiogram demonstrated that all reconstructions were patent through the follow-up period.

CONCLUSIONS

Paraplegia is an extremely morbid complication associated with TAAA repair. We describe a technique that allows reimplantation of almost all intercostal arteries as one patch circumventing the need for selective reimplantation. Furthermore, our technique ensures continued patency of this patch graft as the outflow resistance is decreased by creating a continuous flow loop. Although this is a small case series, we had no incidence of acute or delayed paraplegia in this high risk group. Our technique of intercostal reimplantation is applicable to all open TAAA repair at high-risk for paraplegia and may be an important adjunct in preventing spinal cord ischemia.

Coincidence of spinal canal stenosis and thoracoabdominal aortic aneurysm

We report a case in which a thoracoabdominal aneurysm was present in association with previously unknown critical spinal canal stenosis. In spite of using left heart bypass, systemic hypothermia, and controlled cerebrospinal fluid drainage for spinal cord protection, the patient developed paraplegia following aortic aneurysm repair. Computed tomography scan revealed critical stenosis of the spinal canal that was thought to be sufficient to produce spinal cord compression syndromes including paraplegia.

Combined Use of Adamkiewicz Artery Demonstration and Motor-Evoked Potentials in Descending and Thoracoabdominal Repair

BACKGROUND

We retrospectively reviewed the outcome of distal descending aortic and thoracoabdominal aortic repair with preoperative identification of the Adamkiewicz artery by magnetic resonance angiography and intraoperative monitoring of transcranial motor-evoked potentials.

METHODS

We began combined use of demonstration of the Adamkiewicz artery and intraoperative recording of motor-evoked potentials for prevention of spinal cord complications in descending and thoracoabdominal aortic aneurysm repair in 1998. Ninety-two consecutive patients were studied, with descending aneurysm in 53 and thoracoabdominal aneurysm in 39 patients. The repair was performed through a left thoracic or thoracoabdominal incision, using partial cardiopulmonary bypass to prevent spinal cord injury. Magnetic resonance angiography revealed the Adamkiewicz artery in 70.7% of cases. During surgery, spinal cord ischemia was monitored using motor-evoked potentials. Anastomoses were performed using a segmental clamp technique to reduce spinal cord ischemic time. Based on the findings of magnetic resonance angiography and motor-evoked potentials, the Adamkiewicz artery and other relevant intercostals and lumbar arteries were revascularized or preserved, or both.

RESULTS

The mean durations of partial cardiopulmonary bypass, cross-clamping, and surgery, respectively, were 144.4 +/- 232.2, 106.0 +/- 65.5, and 411.8 +/- 170.7 minutes. Three hospital deaths (3.3%) occurred in patients with a thoracoabdominal aortic aneurysm. Motor-evoked potentials changed in 9 patients (9.8%), in 8 (88.9%) of whom they were eventually restored. Although paraplegia developed in 1 patient (1.1%) with a mycotic descending aneurysm, the other patients survived without spinal cord injury.

CONCLUSIONS

Combined visualization of the Adamkiewicz artery and determination of motor-evoked potentials are useful in preventing spinal cord injury in descending and thoracoabdominal aortic repair.

Chronic descending aortic dissections

Aortic dissection involving the descending aorta has a predictable and often debilitating course of progressive dilatation that occurs once patients survive the acute phase of the disease. Important factors that impact the rate and degree of dilatation include the persistence of a false lumen channel (and the amount of thrombus), the control of hypertension, and the presence of an underlying connective tissue disorder. The mainstay of management of chronic descending aortic dissections is antihypertensive therapy including beta-blockade until the dissected aorta becomes significantly aneurysmal. Surgical management is recommended at that point. Multiple advances have been made that have improved the results of operative repair of aneurysmal descending aortic dissections including circulation management methodologies, CSF drainage, neurocerebral monitoring, and more recently, endovascular therapies. The presentation, diagnosis and management of chronic descending aortic dissections are discussed.

Simultaneous Endovascular Exclusion of Thoracic Aortic Aneurysm with Open Abdominal Aortic Aneurysm Repair

BACKGROUND

The treatment of aneurysms at multiple sites within the aorta is problematic.

METHODS

Between March 2002 and June 2003 in the Department of General, Vascular and Transplant Surgery, Medical University of Warsaw six patients with coexisting abdominal and descending thoracic aortic aneurysms underwent simultaneous open abdominal aortic aneurysm (AAA) repair and endoluminal thoracic aortic aneurysm (TAA) repair. The indication for a combined procedure was a diagnosed descending TAA and AAA with no significant risk factors for open aortic surgery or technical contraindications for endovascular treatment of TAA.

RESULTS

One patient died in the peri-operative period while the other five patients all recovered well after surgery and were discharged with both aneurysms excluded.

CONCLUSION

Endovascular treatment of TAA combined with a simultaneous open AAA repair is an efficient and relatively safe treatment modality in patients with TAA and AAA disqualified from endovascular repair. The fact that thoracotomy is not a necessity significantly lowers the complication rate in these patients.