Spinal Cord Blood Supply Research Articles

Real-Time Monitoring of Mitochondrial NADH and Microcirculatory Blood Flow in the Spinal Cord

We developed a real-time, in vivo monitoring system for the evaluation of spinal cord viability in rats during spinal cord ischemia. The aim of the present study was to apply a real-time multiparametric monitoring system in a rat spinal cord model exposed to ischemia or mechanical compression. The evaluation of spinal cord integrity during spine surgeries is highly important, as it enhances the potential to prevent secondary irreversible damage to the spinal cord tissue. Mitochondrial NADH redox state is the most sensitive parameter for tissue oxygenation state and, together with microcirculatory blood flow, can estimate the metabolic status of the spinal cord tissue. We applied the Tissue Vitality Monitoring System (TVMS) that includes optical fibers for the simultaneous monitoring of the spinal cord blood flow (SCBF) using laser Doppler flowmetry, and the mitochondrial NADH fluorescence using the fluorometric technique. Additionally, systemic arterial blood pressure was measured. Two models involving the interruption of the spinal blood flow were tested: the occlusion of the abdominal aorta (ischemia) and spine mechanical compression. The results clearly demonstrated the link between the level of ischemia and the viability state of the spinal tissue. When SCBF decreased, in both experimental models, mitochondrial NADH was elevated, while reperfusion was associated with NADH oxidation. Nevertheless, during the recovery phase, even though SCBF significantly increased (became hyperemic), no further oxidation of NADH was observed. The monitoring of the mitochondrial function together with SCBF by the TVMS reflects the viability of the spinal cord tissue and, together with the conventional monitoring techniques, may help to evaluate the spine conditions, especially under surgical procedures involving the deterioration of the spinal cord blood supply.

Magnetic resonance angiography of collateral blood supply to spinal cord in thoracic and thoracoabdominal aortic aneurysm patients

Preservation of spinal cord blood supply during descending thoracic (TAA) and thoracoabdominal aortic aneurysm (TAAA) surgery is mandatory to prevent neurologic complications. Although collateral arteries have been identified occasionally and are considered crucial for maintaining spinal cord function in the individual patient, their critical functionality is poorly understood and very little experience exists with visualization. This study investigated whether the preoperative and postoperative presence or absence of collateral arteries detected by magnetic resonance angiography (MRA) is related to spinal cord function during the intraoperative exclusion of the segmental supply to the Adamkiewicz artery. Spinal cord MRA was used to localize the Adamkiewicz artery and its segmental supplier in 85 patients scheduled for open elective surgery for TAA or TAAA. The segmental artery to the Adamkiewicz artery was inside the cross-clamped aortic area in 55 patients, and spinal cord supply was consequently dependent on collateral supply. In these 55 patients the presence of collaterals originating from arteries outside the cross-clamped aortic segment was related to changes in the intraoperative motor-evoked potentials (MEPs) that occurred before corrective measures. Twenty-one patients returned for postoperative MRA. A highly significant (P < .0015) relation was found between the presence of collaterals and intraoperative spinal cord function. In 30 of 31 patients (97%) in whom collaterals were identified, MEPs remained stable. The collaterals in most patients originated caudally to the distal clamp (eg, from the pelvic arteries), which were perfused by means of extracorporeal circulation during cross-clamping. The MEPs declined in 9 of 24 patients (38%) in whom no collaterals were preoperatively visualized. Postoperatively, the 21 patients who had MRA, including 10 in whom preoperatively no collaterals were found, displayed a well-developed collateral network. Collateral arteries supplying the spinal cord can be systematically visualized using MRA. Spinal cord blood supply during open aortic surgery may crucially depend on collateral arteries. Preoperatively identified collateral supply was 97% predictive for stable intraoperative spinal cord function. Patients in whom no collaterals can be depicted preoperatively are at increased risk for spinal cord dysfunction.

Cervical Spine: Case Presentation, Complications, and Their Prevention

Objective. A number of case presentations of catastrophic outcomes after cervical epidural injections have occurred after both interlaminar and transforaminal injection techniques. Practitioners in pain medicine need guidance to avoid these complications Design. A systematic search of the MEDLINE database, electronically available pain journals, and recent pain and spine meeting abstracts was searched for articles relevant to cervical spine interventional procedure complications. Results. A representative case of cervical radicular pain is presented to illustrate key differences of radicular pain presenting in the cervical area from those in the lumbar area Although cervical interlaminar epidural complications more likely involve direct neurological trauma to the spinal cord or spinal nerve, the mechanism for injury after transforaminal epidural corticosteroid injections is less clear. Many investigators hypothesize that particulate steroids may be the primary cause, in that these particles may occlude segmental medullary feeding arteries that reinforce the longitudinal anterior spinal artery supply to the spinal cord. Anatomical nomenclature of spinal cord blood supply and variants of normal are presented. Conclusions. Specific examples of potential injury avoidance strategies are discussed, including: 1) the use of nonparticulate steroid preparations; 2) needle bevel/size and other technical considerations; 3) preprocedural planning and sedation considerations; 4) test dosing with local anesthetics; and 5) imaging considerations, including the use of digital subtraction to better define angiographic patterns. Recommendations for the conduct of cervical epidural injection procedures are discussed.

Noninvasive Imaging of Spinal Cord Blood Supply

Noninvasive Imaging of Spinal Cord Blood Supply

Magnetic resonance angiography and neuromonitoring to assess spinal cord blood supply in thoracic and thoracoabdominal aortic aneurysm surgery

Magnetic resonance angiography and neuromonitoring to assess spinal cord blood supply in thoracic and thoracoabdominal aortic aneurysm surgery

Anatomy of Spinal Cord Blood Supply in the Pig

In a species as popular in research as the pig, little information is available concerning the blood supply and vascular anatomy of the spinal cord and comparability to humans. To visualize vessels contributing to the blood supply of the spinal cord, x-ray digital subtraction angiography and vascular casting by injection of a polymerizing solution of methylmethacrylate were used. The pig has larger internal thoracic arteries and subscapular arteries than the human, providing extensive collateral flow to the lower body, which offers blood supply to the spinal cord through the collaterals. The pig has a fine-caliber vessel plexus providing blood to the neck area, from which flow will reach both the spinal cord and the base of the brain. The segmental thoracic and lumbar arteries are relatively small in pigs, and they almost all originate as a single branch from the aorta and divide after 3 to 4 mm. The segmental vessels show a clear diminution after 2 to 3 cm at the level of the vertebral bodies. Pigs show major differences in the anatomy of the aortic bifurcation compared with humans. The median sacral artery in pigs is a large-caliber vessel, of a size almost comparable to the common iliac artery, with an isolated single dorsal branch leading to the spinal cord. Documenting the anatomic differences in spinal cord blood supply between pigs and humans will aid in the planning of future experimental studies and in determining the clinical relevance of such studies.

Magnetic resonance angiography and neuromonitoring to assess spinal cord blood supply in thoracic and thoracoabdominal aortic aneurysm surgery

Preoperative knowledge of the blood-supplying trajectory to the spinal cord is of interest, because spinal cord ischemia may occur during thoracic aortic aneurysm (TAA) and thoracoabdominal aortic aneurysm (TAAA) repair and possibly leads to paraplegia. The Adamkiewicz artery (AKA) is considered to be the most important blood supplier of the thoracolumbar spinal cord and has therefore been the focus in preoperative diagnostic imaging. However, in TAA(A) patients, the blood supply to the spinal cord may strongly depend on (intersegmental) collateral circulation, because many segmental arteries are occluded as a result of atherosclerosis. Therefore, the importance of preserving the segmental artery supplying the AKA (SA-AKA) is debated. Here it was investigated whether (1) the AKA and its segmental supplier can be imaged by using magnetic resonance (MR) angiography and (2) aortic cross-clamping of the SA-AKA influences intraoperative spinal cord function, monitored by motor evoked potentials (MEPs). Preoperative MR angiography was performed to localize the SA-AKA and the AKA in 60 patients (19 TAA, 7 TAAA I, 18 TAAA II, 9 TAAA III, and 7 TAAA IV). Spinal cord function was monitored during surgery by using MEPs. When MEPs indicated critical ischemia, the SA-AKA was selectively reattached. To test whether aortic cross-clamping of the SA-AKA was associated with MEP decline, the Fisher statistical exactness test was applied. The AKA and SA-AKA could be localized in all 60 (100%) patients between vertebral levels T8 and L2 (72% left sided). In 44 (73%) patients, the SA-AKA was cross-clamped, which led in 32% (14/44) of cases to MEP decline. Reattachment of the preoperatively localized SA-AKA re-established MEPs and, thus, spinal cord function in 12 of 14 cases. When the SA-AKA was outside the area cross-clamped, the MEPs always remained stable. A significant association (P < .01) was found between the location of the SA-AKA relative to the aortic cross-clamps and the MEPs. The AKA can be localized before surgery in 100% of TAA(A) patients by using MR angiography. Location of the SA-AKA outside the cross-clamped aortic area is attended with stable MEPs. Interestingly, it was found that in most patients in whom the SA-AKA was cross-clamped, MEPs were not affected, thus indicating sufficient collateral blood supply to maintain spinal cord integrity. Nevertheless, preoperative knowledge of SA-AKA location is of importance, because in 32% of patients, spinal cord function was dependent on this supplier. Revascularization of the SA-AKA can thereby reverse spinal cord dysfunction.

Direct emergence of the dorsospinal artery from the aorta and spinal cord blood supply

Direct emergence of a dorsospinal artery from the aorta is a rare anatomic variant, of which a total of seven cases have been reported. This report offers an additional angiographic observation and reviews the literature. Two observations of common intercostal trunks documented during spinal angiography are described. In the first observation, the common intercostal trunk provided complete blood supply to two adjacent vertebral levels (T11 and T12). In other words, the trunk included an intercostal branch and a dorsospinal branch for each level. In the second observation, the common intercostal trunk provided an intercostal branch for each level (T9 and T10), but only one dorsospinal branch (T10). An isolated dorsospinal artery (DA) originated separately from the aorta at the T9 level, and provided a significant contribution to the anterior spinal axis. The two reported cases illustrate the concept of "complete" versus "incomplete" common intercostal trunks. In instances where an incomplete trunk is documented, a separate DA originating directly from the aorta must be looked for. A review of the literature indicates a tendency for isolated DAs to participate in the blood supply to the spinal cord.

Reversal of delayed-onset paraplegia with thrombectomy of an interposed graft for the intercostal artery after thoracic descending aortic aneurysm repair

A 78-year-old woman who had previously undergone prosthetic graft replacement of the total aortic arch was admitted to repair a chronic expanding type IIIb dissecting aneurysm. Firstly the patient's abdominal aorta was replaced with a prosthetic graft without any complications, then the thoracicdescending aorta was repaired five months later. Surgery for the thoracic descending aorta was performed with distal perfusion, cerebrospinal fluid drainage, somatosensory evoked potential (SEP) monitoring and reimplantation of three pairs of intercostal arteries. During surgery, SEP showed no significant changes, and the patient awoke without paraplegia three hours after the surgery. However, she developed bilateral complete paraplegia eight hours after the surgery. Reexploration demonstrated thrombo-occlusion of the sidearm graft for reimplantation of the Th10 intercostal artery. After thrombectomy of the sidearm graft, there was gradual neurological recovery and the patient was ambulatory when discharged. Quick treatment to restore the spinal cord blood supply promoted recovery from paraplegia.

BLOOD SAVING IN PEDIATRIC SPINAL SURGERY: LITERATURE REVIEW

The analysis of literature data on blood saving in pediatric spinal surgery is presented in the review. The advantages and shortcomings of each method are critically evaluated. It is marked that the highest efficiency is achieved by combination of several methods in one patient. Special attention is paid to the risk of reducing spinal cord blood supply and necessity of thorough monitoring of systemic hemodynamics and oxygen transport.

Magnetic resonance angiographic localization of the artery of Adamkiewicz for spinal cord blood supply

Background The purpose of this study was to determine whether the artery of Adamkiewicz (ARM) can be detected by magnetic resonance angiography and to determine the usefulness of preoperative magnetic resonance angiography evaluation of the ARM. Methods Between April 2000 and December 2003, 120 patients underwent magnetic resonance angiography for detection of the ARM. The morphology of the anterior spinal artery at the ARM junction, as revealed by magnetic resonance angiography, in 99 patients in whom ARM was preoperatively detected was classified into the following three types: noncontinuation of the anterior spinal artery above the ARM junction (type A), continuation of the anterior spinal artery above and below the ARM junction (type B), and noncontinuation of the anterior spinal artery below the ARM junction (type C). Results The ARMs were detected in 99 (83%) of 120 patients, and from a total of 110 ARMs 105 (95%) originated from intercostal arteries branching from the left side and 94 (86%) originated between Th9 and Th11. Two ARMs were found in 11 (11%) of 99 patients in whom ARMs were detected. In 107 patients, who underwent magnetic resonance angiography to reveal the morphology of the anterior spinal artery at the ARM junction, the patterns of the anterior spinal artery were type A in 59 patients (55%), type B in 21 patients (20%), type C in 3 patients (3%) and not classified in 24 patients (22%). No spinal cord injury occurred in patients in whom the ARM had been preoperatively detected. Conclusions Preoperative detection of the ARM is possible by magnetic resonance angiography and is very useful for reducing the incidence of ischemic injury of the spinal cord.

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

ObjectiveThoracic and thoracoabdominal aortic repair are still complicated by spinal cord ischemia and paraplegia. The aim of the present article is to present the results of an anatomical study conducted by means of both postmortem injection of the vertebral artery and perfusion of the abdominal aorta. MethodsThe spinal cord blood supply was investigated in 51 Caucasian cadavers: in 40 cases a methylene blue solution was hand-injected into the vertebral artery, whereas in the remaining 11 cases the abdominal aorta was perfused with a methylene blue solution by means of a roller pump. The level and side of the arteria radicularis magna and the continuity of the anterior spinal artery were recorded. ResultsThe anterior spinal artery was a continuous vessel without interruptions along the spinal cord in all 51 cases. The arteria radicularis magna level was variable, ranging from T9 to L5. The arteria radicularis magna arose from a lumbar artery in 36 cases (70.5%) and it was left-sided in 32 cases (62.7%). ConclusionsThe anterior spinal artery constitutes an uninterrupted pathway between the vertebral arteries, the arteria radicularis magna, and the posterior intercostal and lumbar arteries. Moreover, the arteria radicularis magna arises from a lumbar artery in most of cases. Therefore, the sacrifice of the intercostal arteries during a thoracic aorta repair could be justified, at least from an anatomical standpoint. However, if an extended thoracoabdominal aortic repair is planned, it may be prudent to preserve the blood flow from the lumbar arteries.

Peculiarities of Cervical Spinal Cord Blood Supply

The peculiarities of cervical spinal cord blood supply were studied on 34 autopsied specimens. It was detected that both a. anterior spinalis, gone away from intracerebral zone of a. vertebralis and a. anterior radiculo-medullaris approaching the a. anterior spinalis system with C2-8 radicis played an equally important role in blood supply of the cervical spinal cord. The most significant importance had C5 left and C7 right a. radiculo-medullaris, that were noted in 65% of specimens. For cervical spinal cord the branching type of blood supply was more characteristic (67,7% of cases). In that type the number of a. radiculo-medullaris ranged from 2 to 8 (mean 4,4). That peculiarity significantly increases the probability of restoration of blood circulation in injury or other pathology of a. anterior spinalis.

Importance of extrasegmental vessels for spinal cord blood supply in a chronic porcine model.

Our purpose was to investigate the interaction of the important components of spinal cord blood supply in the pig model to enable its use for future studies of spinal cord protection. Twenty-five juvenile pigs (20-22 kg) underwent serial intercostal (IC) or lumbar artery (LA) ligation until disappearance of motor evoked potentials (MEPs). Pigs underwent sequential craniocaudal IC/LA ligation alone (n=5); following clamping of both subclavian arteries (n=4), or clamping of the median sacral artery (MSA, n=4). Animals also underwent serial caudocranial clamping of LA/IC alone (n=4); preceded by clamping of the subclavian arteries (n=4), or of the MSA (n=4). Results were verified by Tarlov's scores and perioperative angiography. All animals with MEP loss suffered postoperative paraplegia. Groups were equivalent with regard to stable arterial pressures (64.6+/-3.1 degrees C) throughout the experiment, temperature (36+/-1.1 degrees C) and other physiological parameters. Mean number of clamped IC/LA before MEP loss for cranio-caudal clamping direction was 12.8+/-0.8 for segmental arteries isolated, 9+/-0.8 if both subclavian arteries were ligated previously and only 4.3+/-0.5 IC if the median sacral artery was clamped before. Mean number of clamped LA for caudo-cranial clamping direction was 5.8+/-0.9 for segmental lumbar arteries, 5.5+/-0.6 LA if both subclavian arteries were ligated previously and 3.5+/-0.6 if the median sacral artery was clamped before. This study confirms the importance of lumbar and MSA arteries to cord viability. It documents the interaction of the subclavian and MSA (roughly equivalent to the hypogastric arteries in humans) with segmental vessels in providing spinal cord blood supply. It also provides the physiologic basis for use of the pig model for studies of spinal cord protection in aortic surgery.

Spinal cord blood supply in patients with thoracoabdominal aortic aneurysms

Objective: In patients with thoracoabdominal aortic aneurysms (TAAAs), the blood supply to the spinal cord is highly variable and unpredictable because of obstructed intercostal and lumbar arteries. This study was performed for the prospective documentation of patent segmental arteries during TAAA repair and the assessment of their functional contribution to the spinal cord blood supply. Methods: TAAA repair was performed in 184 consecutive patients (68 with type I aneurysm, 91 with type II, and 25 with type III) according to a protocol that included left heart bypass grafting, cerebrospinal fluid drainage, and the monitoring of motor-evoked potentials (MEPs). Patent intercostal and lumbar arteries were documented, and all reattached, selectively grafted, and oversewn segmental arteries were noted. MEP amplitude that decreased to less than 25% of baseline was considered an indication of critical spinal cord ischemia and prompted spinal cord revascularization. Results: Adequate MEP levels were encountered in 183 of 184 patients. One patient had early paraplegia (absent MEPs), two patients had delayed paraplegia develop, and two patients had temporary paraparesis, which accounted for an overall neurologic deficit of 2.7%. The median total number of patent intercostal and lumbar arteries in type I, II, and III aneurysms was three, five, and five, respectively. In eight of 68 type I cases, no segmental arteries were seen between the fifth thoracic vertebrae (T5) and the first lumbar vertebrae (L1) and MEP levels remained adequate because of distal aortic perfusion. In 18 of 91 type II cases, the aortic segment T5 to L1 did not contain patent arteries, and in six of these patients, the segment L1 to L5 did not have lumbar arteries either. In the latter patients, MEP levels depended on the pelvic circulation provided with the left heart bypass graft. In the other 12 of 91 type II cases, the only patent arteries were the lumbar arteries between L3 and L5. The loss of MEPs could be corrected with the reattachment of these arteries. In seven of 25 type III cases, the MEP levels also depended on lumbar arteries L3 to L5 and in three of 25 cases, no segmental arteries were available and MEP levels recovered after the reperfusion of the pelvic circulation. With the combination of the findings of type II and III cases, spinal cord perfusion was directed by lower lumbar arteries in 16% of the cases (19 of 116) and pelvic circulation in 8% of the cases (nine of 116). Conclusion: In patients with TAAA, most intercostal and lumbar arteries are occluded and spinal cord perfusion depends on an eminent collateral network, which includes lumbar arteries and pelvic circulation. The monitoring of MEPs is a sensitive technique for the assessment of spinal cord ischemia and the identification of segmental arteries that critically contribute to spinal cord perfusion. Surgical strategies on the basis of this technique reduced the incidence rate of neurologic deficit to less than 3%. (J Vasc Surg 2002;35:30-7.)

Spinal cord blood supply in patients with thoracoabdominal aortic aneurysms

Spinal cord blood supply in patients with thoracoabdominal aortic aneurysms

Aspects of the spinal cord circulation as assessed by intrathecal oxygen tension monitoring during various arterial interruptions in the pig

Objective: We sought to study the effect of various modes of interruption of the spinal cord blood supply on intrathecal oxygenation. Methods: In 24 pigs intrathecal PO2, PCO2, and pH were continuously monitored with a multiparameter catheter (Paratrend 7, Biomedical Sensors; Diametrics Medical, Inc, St Paul, Minn) during and after aortic crossclamping or selective interruption of segmental arteries and proximal collateral circulation. Results: Proximal aortic clamping (n = 6) produced complete ischemia, whereas a second clamp close to the celiac trunk (n = 4) partly protected against spinal cord ischemia. This is explained by prevention of the steal phenomenon in the excluded part of the aorta. Adding clamps to the subclavian arteries (n = 6) created complete spinal ischemia as the collateral circulation was interrupted. In another group (n = 4) all segmental arteries below T5 were occluded with no reaction in the intrathecal variables. Additional selective clamping of supreme intercostal arteries (n = 4) showed the relative importance of the subclavian and vertebral collateral pathways. Conclusions: Continuous intrathecal PO2 was monitored during various modes of interruption of the spinal cord blood supply. This provided insight into the ischemia mechanisms and relative importance of the segmental contribution and proximal collateral pathways of the spinal cord circulation in pigs. A short literature review is given, and aspects of comparative anatomy are discussed. (J Thorac Cardiovasc Surg 2001;121:762-72)

Pharmacologic neuroprotection in experimental spinal cord ischemia: a systematic review.

Various surgical procedures may cause temporary interruption of spinal cord blood supply and may result in irreversible ischemic injury and neurological deficits. The cascade of events that leads to neuronal death following ischemia may be amenable to pharmacological manipulations that aim to increase the tolerable duration of ischemia. Many agents have been evaluated in experimental spinal cord ischemia (SCI). In order to investigate whether an agent is available that justifies clinical evaluation, the literature on pharmacological neuroprotection in experimental SCI was systematically reviewed to assess the neuroprotective efficacy of the various agents. In addition, the strength of the evidence for neuroprotection was investigated by analyzing the methodology. The authors used a systematic review to conduct this evaluation. The included studies were analyzed for neuroprotection and methodology. In order to be able to compare the various agents for neuroprotective efficacy, relative risks and confidence intervals were calculated from the data in the results sections. A total of 103 studies were included. Seventy-nine different agents were tested. Only 14 of the agents tested did not afford protection at all. A large variation was observed in the experimental models to produce SCI. This variation limited comparison of the individual agents. In 48 studies involving 31 single agents, the relative risks and confidence intervals could be calculated. An analysis of the methodology revealed poor temperature management and lack of statistical power in the majority of the 103 studies. The results suggest that numerous agents may protect the spinal cord from transient ischemia. However, poor temperature management and lack of statistical power severely weakened the evidence. Consequently, clinical evaluation of pharmacological neuroprotection in surgical procedures that carry a risk of ischemic spinal cord damage is not justified on the basis of this study.

Prevention of paraplegia in pigs by selective segmental artery perfusion during aortic cross-clamping

Purpose: During thoracoabdominal aortic aneurysm repair, a prolonged interruption of the spinal cord blood supply can result in irreversible spinal cord damage. The aim of this study was to investigate whether selective segmental artery perfusion during aortic clamping could prevent paraplegia in pigs. Methods: Specially designed segmental artery perfusion catheters, which could be attached to an extracorporeal bypass graft system, were used. In experiment I (n = 10), it was assessed whether selective segmental artery perfusion could reverse electrophysiologic evidence of spinal cord ischemia and maintain transcranial motor evoked potentials (tc-MEPs) during 60 minutes of aortic cross-clamping. The abdominal aorta, containing critical segmental arteries, was bypassed through use of an aortoaortic bypass graft system. After the disappearance of tc-MEPs, an aortotomy was followed by selective segmental artery perfusion. In experiment II (n = 10), the aim was to determine whether selective segmental artery perfusion could prevent paraplegia. In five animals (group A), aortic cross-clamping was followed by selective segmental artery perfusion; five control animals (group B) underwent segmental artery blockade only. Postoperative hind limb function and spinal cord histopathology were evaluated on the third postoperative day. Results: In experiment I, tc-MEPs disappeared within 3.7 ± 3.7 minutes after cross-clamping and returned in all animals in 8.5 ± 5.3 minutes after selective perfusion. During the study period, tc-MEP amplitudes recovered to a median of 49% (range, 28%-113%) of baseline values. Total bypass graft flow was 880 ± 294 mL/min, of which 184 ± 54 mL/min was directed to the selective perfusion catheters. The flow in individual catheters was 52 ± 13 mL/min. In experiment II, all perfused animals demonstrated normal hind limb function, whereas four of five control animals were paraplegic on day 3 (P =.04) In the perfused animals, histopathologic examination showed either no spinal cord damage or eosinophilic neurons only, whereas in paraplegic controls there was infarction in large areas of the cord (P <.0001). Conclusion: In pigs, selective segmental artery perfusion can provide sufficient spinal cord blood flow to prevent paraplegia resulting from 60 minutes of aortic clamping, as shown by clinical outcomes and histopathologic examination. (J Vasc Surg 2000;32:160-70.)

Epidural cooling for spinal cord protection during thoracoabdominal aneurysm repair: A five-year experience

Purpose: We developed and applied a method for providing regional spinal cord hypothermia with epidural cooling (EC) during thoracoabdominal aneurysm (TAA) repair. Preliminary results indicated significant reduction in spinal cord ischemic complications (SCI), compared with historical controls, and a 5-year experience with EC was reviewed.Methods: From July 1993 to September 1998, 170 patients with thoracic aneurysms (n = 14; 8.2%) or TAAs (types I and II, n = 83 [49%]; type III, n = 66 [39%]; type IV, n = 7 [4.1%]) were treated with EC. An earlier aneurysm resection was noted in 44% of patients, an emergent operation was noted in 20% of patients, and an aortic dissection was noted in 16% of patients. The EC was successful (mean cerebrospinal fluid [CSF] temperature at cross-clamp, 26.4 ± 3°C) in 97% of cases, with all 170 patients included in an intention-to-treat analysis. The operation was performed with a clamp/sew technique (98% patients) and selective (T9 to L1 region) reimplantation of intercostal vessels. Clinical and EC variables were examined for association with operative mortality and SCI by means of the Fischer exact test, and those variables with a P value less than .1 were included in multivariate logistic regression analysis.Results: The operative mortality rate was 9.5% and was weakly associated (P = .07) with SCI; postoperative cardiac complications (odds ratio [OR], 35.3; 95% CI, 5.3 to 233; P < .001) and renal failure (OR, 32.2; 95% CI, 6.6 to 157; P < .001) were the only independent predictors of postoperative death. SCI of any severity occurred in 7% of cases (type I/II, 10 of 83 [12%]; all other types, 2 of 87 [2.3%]), versus a predicted (Acher model) incidence of 18.5% for this cohort (P= .003). Half the deficits were minor, with good functional recovery, and devastating paraplegia occurred in three patients (2.0%). Independent correlates of SCI included types I and II TAA (OR, 8.0; 95% CI, 1.4 to 46.3; P = .021), nonelective operation (OR, 8.3, 95% CI, 1.8 to 37.7; P = .006), oversewn T9 to L2 intercostal vessels (OR, 6.1; 95% CI, 1.3 to 28.8; P = .023), and postoperative renal failure (OR, 23.6; 95% CI, 4.4 to 126; P < .001). These same clinical variables of nonelective operations (OR, 7.7; 95% CI, 1.4 to 41.4; P = .017), oversewn T9 to L2 intercostal arteries (OR, 9.7; 95% CI, 1.5 to 61.2; P = .016), and postoperative renal failure (OR, 20.8; 95% CI, 3.0 to 142.1; P = .002) were independent predictors of SCI in the subgroup analysis of high-risk patients, ie, patients with type I/II TAA.Conclusion: EC has been effective in reducing immediate, devastating, total paraplegia after TAA repair. A strategy that combines the neuroprotective effect of regional cord hypothermia, avoiding the sacrifice of potential spinal cord blood supply, and postoperative adjuncts (eg, avoidance of hypotension, CSF drainage) appears necessary to minimize SCI after TAA repair.