The anatomy of the spinal cord collateral circulation

Anterior spinal cord syndrome from a spinal epidural hematoma following removal of an epidural catheter

PURPOSE

Spinal epidural hematoma (SEH) is a rare yet significant complication associated with neuraxial anesthesia. Here, we present the case of a 74-yr-old male who underwent open repair of an abdominal aortic aneurysm. Following the removal of an epidural catheter, the patient developed anterior spinal cord syndrome due to an SEH despite having a normal coagulation profile.

CLINICAL FEATURES

This patient's neurologic presentation was marked by a loss of motor function while maintaining fine touch sensation distal to the spinal cord injury. Initial truncal computed tomography (CT) angiography failed to detect vascular compromise or diagnose the SEH. Subsequently, delayed magnetic resonance imaging (MRI) revealed a multilevel thoracic epidural hematoma, spinal cord infarction, and ischemia. Immediate surgical decompression was performed, but unfortunately, the patient had a poor outcome.

CONCLUSION

Anterior spinal cord syndrome (ASCS) represents an uncommon neurologic manifestation of SEH, which is typically characterized by a triad of back pain and sensory and motor deficits. Although the initial CT scan was necessary to diagnose the postvascular surgery complication, it did not immediately detect the SEH. In cases of ASCS subsequent to thoracic epidural placement and removal, MRI is the preferred imaging modality for precise diagnosis and assessment of the need for surgical intervention. Despite adherence to anticoagulation guidelines, patients undergoing neuraxial anesthesia may face an elevated risk of developing SEH. Health care professionals should remain vigilant in monitoring for neurologic abnormalities following epidural catheter insertion or removal, particularly in the context of vascular surgery.

Predictive value of preoperative platelet count and D-dimer levels for spinal cord injury following acute type a aortic dissection

BACKGROUND

This study aims to identify the risk factors contributing to spinal cord injury (SCI) following a type A acute aortic dissection (TA-AAD).

METHODS

This retrospective study was conducted at a single center and involved 481 patients who received frozen elephant trunk stent implantation for TA-AAD. Additionally, these patients underwent total arch replacement with deep hypothermic circulatory arrest. This study was performed at Fuwai Hospital between September 2016 and April 2020.

RESULTS

The resulting data of the multivariate logistic regression analysis demonstrated that preoperative platelet count (odds ratio [OR] = 0.774) and D-dimer levels (OR = 2.247) could serve as independent predictors for postoperative SCI in patients with TA-AAD.

CONCLUSION

The findings indicate that preoperative platelet count and D-dimer levels are independent risk factors for postoperative SCI in patients with TA-AAD. This study holds significant clinical implications regarding the prognosis and therapeutic responses for patients with TA-AAD.

Simultaneous upper and lower body perfusion using hypothermia during thoracoabdominal aortic surgery

BACKGROUND

In open thoracoabdominal aortic aneurysm (TAAA) repair, we have been performing vascular reconstruction under moderate to deep hypothermia and assisted circulation using simultaneous upper and lower body perfusion. This method is effective for protecting the spinal cord and the brain, heart, and abdominal organs and for avoiding lung damage.

METHODS

TAAA repair was performed under hypothermia at 20-28 °C in 18 cases (Crawford type I in 0 cases, type II in 5, type III in 3, type IV in 4, and Safi V in 6) between October 2014 and January 2023. Cardiopulmonary bypass was conducted by combined upper and lower body perfusion, with perfusion both via the femoral artery and either transapically or via the descending aorta or the left brachial artery.

RESULTS

The ischemic time for the artery of Adamkiewicz and the main segmental arteries was 40-124 min (75 ± 33 min). No spinal cord ischemic injury or brain or heart complications occurred. One patient with postoperative right renal artery occlusion and one with an infected aneurysm required tracheostomy, but the intubation time for the other 16 was 32 ± 33 h. The duration of postoperative intensive care unit stay was 6.5 ± 6.2 days, the length of hospital stay was 29 ± 15 days, and no in-hospital deaths occurred.

CONCLUSIONS

Simultaneous upper and lower body perfusion under moderate to deep hypothermia during thoracoabdominal aortic surgery may avoid not only spinal cord injury, but also cardiac and brain complications.

Blood pressure control with phenylephrine or dobutamine: a randomized controlled trial comparing effects on cerebral and paravertebral tissue oxygen saturation measured with near-infrared spectroscopy

Preserving haemodynamics is expected to positively affect tissue oxygen saturation. We hypothesized that maintaining mean arterial blood pressure (MAP) (using phenylephrine (PE) or dobutamine (Dobu)) would equally affect regional cerebral and paravertebral tissue saturation (rScO2 and rSpvO2, respectively). Thirty-four patients were randomly assigned to receive either PE or Dobu, in order to keep MAP within 20% of the preoperative value. Their effect on haemodynamics, rScO2 and rSpvO2 at thoracic level T3-T4, T9-T10 and lumbar level L1-L2 was calculated at different doses. Drug-induced haemodynamic effects differed between groups (∆MAP: -2%±21 and - 19%±17, ∆CI: -14.6%±14.6 and 24.1%±49.9, ∆HR: -21%±21 and 0%±16 for PE and Dobu, respectively). Both groups exhibited a significant decrease in rScO2, with a more pronounced decline in the PE group (-14.1%±16.1) compared to the Dobu group (-5.9%±10.6). There were no significant changes at the paravertebral level in either group, but a slight but statistically significant difference was detected between the two groups at T3-T4 and L1-L2. Current guidelines advocate maintaining adequate systemic blood pressures to prevent spinal cord ischaemia in specific procedures. However, it is still unknown which circulatory supportive drug is more beneficial for maintaining spinal cord perfusion. Our data indicates that, when used for maintenance of blood pressure within a 20% range of preoperative values, neither phenylephrine nor dobutamine affect paravertebral tissue saturation.

Collateral network concept in 2023

Extensive thoracoabdominal aortic aneurysm repair can cause spinal cord ischemia which significantly impacts survival and quality of life. Although this complication is uncommon, it is important to recognize the pathophysiology and preventative measures. In the 1990s, Dr. Griepp and colleagues proposed the existence of an extensive collateral network that supports spinal cord perfusion, "the collateral network concept". This includes an interconnecting complex of vessels in the intraspinal, paraspinous, and epidural spaces, and in the paravertebral muscles, involving the intercostal and lumbar segmental arteries as well as the subclavian and hypogastric (iliac) arteries. In this concept, as opposed to the one major segmental input model such as the Adamkiewicz artery, recognition of the importance of multiple inputs to the spinal circulation is paramount to maintaining the spinal blood flow and preventing spinal cord ischemia. In this article, we review the current evidence of the collateral concept and its application in aortic surgery.

Safety of cerebrospinal fluid drainage in descending and thoracoabdominal aortic replacement surgery

Background

Spinal cord injury (SCI) remains a significant morbidity of surgical repair of descending thoracic aortic aneurysms (DTAA) and thoracoabdominal aortic aneurysms (TAAA). We present our 17-year experience with cerebrospinal fluid drainage (CSFD) as a protective strategy during open surgical repair of descending and thoracoabdominal aortic disease.

Methods

We conducted a retrospective chart review of 132 patients who underwent open surgical repair of DTAA and TAAA and dissections with concurrent use of CSFD for spinal cord protection. Information regarding survival, postoperative course, and complications related to CSFD use were extracted from electronic health records (EHR) and analyzed.

Results

Mean patient age was 65.4±13.0 years, and 82 (62.1%) were male. A CSFD was successfully inserted in all patients. The mean hospital length of stay after surgery was 12.2±11.2 days, and in-hospital mortality was 7.6%. Postoperative transient paresis was observed in 5 patients (3.8%), and permanent paraplegia was seen in 4 (3.0%). CSFD related complications were reported in 25 patients (19%). Complications included persistent cerebrospinal fluid (CSF) leakage, blood-tinged CSF (with subdural hematoma reported in 3 patients) and spinal cutaneous fistula in 9 (7%), 14 (11%), and 1 (1%), respectively. Long term survival was 50.9% at 15 years.

Conclusions

CSFD is associated with minor complications, without major sequalae. It is a safe practice and likely contributes innocuously to decreased SCI in patients undergoing open repair of DTAA and TAAA.

False lumen-dependent segmental arteries are associated with spinal cord injury in frozen elephant trunk procedure for acute type I aortic dissection

Objective

To investigate the association between false lumen (FL) dependency of segmental arteries (SAs) at T9-L3 levels and the risk of spinal cord injury (SCI) following total arch replacement and frozen elephant trunk (FET) implantation in the setting of acute DeBakey type I aortic dissection (AAD).

Methods

The study involved consecutive patients with AAD who underwent total arch replacement and FET implantation between 2020 and 2022. Primary outcome was postoperative SCI. The inverse probability of treatment weighting (IPTW) method was employed to minimize the impact of no-randomization bias. Antegrade placement of FET was followed by end-to-end anastomosis of a 4-branch arch graft at the proximal landing site of FET.

Results

A total of 146 patients were included (age, 50.5 ± 11.7 years, 115 male), of whom 35 (24%) had SAs at T9-L3 levels completely dependent on FL (FL-dependency group). There was no significant difference in early (30-day or in-hospital) mortality rates between FL-dependency (14.3%) and FL-independency (18.0%) groups (P = .80), however, the rate of SCI was significantly higher in the FL-Dependency group (34.3% vs 2.7%, P < .001). After adjustments, FL dependency was associated with a significantly increased risk of SCI (odds ratio, 13.1; 95% confidence interval, 4.2-41.0; P < .001), whereas it was not significantly associated with risks of early mortality or other major complications (P = .16-.98).

Conclusions

FL dependency of SAs at the T9-L3 levels was significantly associated with the development of SCI following FET implantation in AAD, warning against its uses on patients presenting with FL dependency of SAs at critical segments.

Isolated aneurysms of the spinal circulation: a systematic review of the literature

Aneurysms arising in the spinal circulation are rare and underreported. The objective of this study was to systematically review the English literature on different aspects of isolated spinal aneurysms using the PubMed, Ovid MEDLINE, and Google Scholar databases. Eighty-two papers reporting 107 individual patient cases were included. Most isolated spinal aneurysms have a fusiform morphology, and are most commonly found in the anterior spinal artery at the thoracic or cervical levels. Subarachnoid hemorrhage is the most common form of presentation, and sudden onset back pain is the most common initial symptom. The diagnosis of spinal aneurysms requires a high degree of clinical suspicion. Because of their small size, they can be missed on CT/MR angiography and spinal angiogram may be employed. Treatment of spinal aneurysms should be individualized on a case-by-case basis. Conservative management can be a valid option in spinal aneurysms where the risk of treatment is high. Surgical or endovascular intervention may be indicated in cases of significant or progressive neurologic decline due aneurysmal mass effect, or progressive growth of the aneurysm despite conservative treatment.

Utility of spinal angiography and arterial embolization in patients undergoing CT guided alcohol injection of aggressive vertebral hemangiomas

PURPOSE

The purpose of this study is to evaluate the role of spinal angiography and arterial embolization in avoiding spinal cord ischemia in patients undergoing CT-guided alcohol injection of aggressive vertebral hemangiomas.

METHODS

In this retrospective study, patients with vertebral hemangioma who underwent CT-guided direct alcohol injection between January 2007 and October 2018 were identified. Of 28 such patients, 26 had neurological deficits, and 2 had only back pain or radiculopathy. Direct alcohol injection without prior arterial embolization was done in 17 patients. Direct alcohol injection with prior arterial embolization was done in 11 patients. Clinical outcome was assessed immediately after the intervention and at follow-up.

RESULTS

Three patients, who underwent alcohol injection without trans-arterial embolization, had worsening of neurological deficits in the post procedure period due to spinal cord ischemia. No complications related to spinal cord ischemia were noted in the embolization group. There was no significant difference in the outcomes between the two groups if the three patients with complications are excluded (p = 0.34).

CONCLUSION

While CT-guided direct alcohol injection is effective in the management of symptomatic and aggressive vertebral hemangiomas, spinal angiography and trans-arterial embolization of the blood supply to the vertebral body hemangioma, prior to the direct transpedicular alcohol embolization of the lesion, improves the safety of the procedure.

Towards rapid intraoperative axial localization of spinal cord ischemia with epidural diffuse correlation monitoring

Spinal cord ischemia leads to iatrogenic injury in multiple surgical fields, and the ability to immediately identify onset and anatomic origin of ischemia is critical to its management. Current clinical monitoring, however, does not directly measure spinal cord blood flow, resulting in poor sensitivity/specificity, delayed alerts, and delayed intervention. We have developed an epidural device employing diffuse correlation spectroscopy (DCS) to monitor spinal cord ischemia continuously at multiple positions. We investigate the ability of this device to localize spinal cord ischemia in a porcine model and validate DCS versus Laser Doppler Flowmetry (LDF). Specifically, we demonstrate continuous (>0.1Hz) spatially resolved (3 locations) monitoring of spinal cord blood flow in a purely ischemic model with an epidural DCS probe. Changes in blood flow measured by DCS and LDF were highly correlated (r = 0.83). Spinal cord blood flow measured by DCS caudal to aortic occlusion decreased 62%. This monitor demonstrated a sensitivity of 0.87 and specificity of 0.91 for detection of a 25% decrease in flow. This technology may enable early identification and critically important localization of spinal cord ischemia.

Findings of Electrodiagnostic Studies in Moderate to Severe Lumbar Central Spinal Stenosis-Electrodiagnostic Studies in Lumbar Central Spinal Stenosis

Purpose: The purpose of this study was to investigate the findings of electrodiagnostic studies (nerve conduction study (NCS) and electromyography (EMG)) in patients with moderate and severe lumbar central spinal stenosis (LCSS). Methods: We retrospectively reviewed the medical records of Ulsan University Hospital and identified 32 consecutive patients (mean age = 66.9 ± 7.4 years; male:female = 8:24) with LCSS. Based on the results of T2 axial magnetic resonance imaging at the level of L4–5, patients were categorized as having severe (n = 14) or moderate LCSS (n = 18). Results from NCS and EMG were retrieved. Additionally, we included 15 age- and sex-matched volunteers without LCSS (mean age = 65.2 ± 8.0 years; male:female = 4:11) to serve as a control group. Results of NCS and EMG were compared between the three groups. Results: We found that, compared to normal subjects, patients with moderate or severe LCSS presented significantly lower distal amplitudes of the compound motor action potential of both peroneal and tibial nerves. Regarding EMG, positive sharp waves and fibrillation potentials were exclusively observed in patients with severe LCSS group (28.6%). Conclusion: Electrodiagnostic studies were significantly altered in patients with moderate and severe LCSS. Our results may be helpful to diagnose LCSS-induced radiculopathy and to differentiate it from other causes of peripheral nerve pathologies.

The Safety Profile of Intentional or Iatrogenic Sacrifice of the Artery of Adamkiewciz and Its Vicinity's Spinal Segmental Arteries: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

There is paucity of consensus on whether (1) the artery of Adamkiewicz (AoA) and (2) the number of contiguous segmental spinal arteries (SSAs) that can be safely ligated without causing spinal cord ischemia. The objective of this review is to determine the risk of motor neurological deficits from iatrogenic sacrifice of the (1) AoA and (2) its vicinity's SSAs.

METHODS

Systematic review of the spine and vascular surgery was carried out in accordance to PRISMA guidelines. Outcomes in terms of risk of postoperative motor neurological deficit with occlusion of the AoA, bilateral contiguous SSAs, or unilateral contiguous SSAs were analyzed.

RESULTS

Ten articles, all retrospective case series, were included. Three studies (total N = 50) demonstrated a postoperative neurological deficit risk of 4.0% when the AoA is occluded. When 1 to 6 pairs of SSAs (without knowledge of AoA location) were ligated, the postoperative neurological deficit risk was 0.6%, as compared with 5.4% when more than 6 bilateral pairs of SSAs were ligated (relative risk [RR] = 0.105, 95% CI 0.013-0.841, P = .0337). For unilateral ligation of SSAs of two to nine levels, the risk of postoperative neurological deficit does not exceed 1.3%.

CONCLUSION

The current best evidence indicates that (1) occlusion of the AoA and (2) occlusion of up to 6 pairs of SSAs is associated with a low risk of postoperative neurological deficit. This limited number of low quality studies restrict the ability to draw definitive conclusions. Ligation of AoA and SSAs should only be undertaken when absolutely required to mitigate the small but devastating risk of paralysis.

Arteriogenesis of the Spinal Cord-The Network Challenge

Spinal cord ischemia (SCI) is a clinical complication following aortic repair that significantly impairs the quality and expectancy of life. Despite some strategies, like cerebrospinal fluid drainage, the occurrence of neurological symptoms, such as paraplegia and paraparesis, remains unpredictable. Beside the major blood supply through conduit arteries, a huge collateral network protects the central nervous system from ischemia—the paraspinous and the intraspinal compartment. The intraspinal arcades maintain perfusion pressure following a sudden inflow interruption, whereas the paraspinal system first needs to undergo arteriogenesis to ensure sufficient blood supply after an acute ischemic insult. The so-called steal phenomenon can even worsen the postoperative situation by causing the hypoperfusion of the spine when, shortly after thoracoabdominal aortic aneurysm (TAAA) surgery, muscles connected with the network divert blood and cause additional stress. Vessels are a conglomeration of different cell types involved in adapting to stress, like endothelial cells, smooth muscle cells, and pericytes. This adaption to stress is subdivided in three phases—initiation, growth, and the maturation phase. In fields of endovascular aortic aneurysm repair, pre-operative selective segmental artery occlusion may enable the development of a sufficient collateral network by stimulating collateral vessel growth, which, again, may prevent spinal cord ischemia. Among others, the major signaling pathways include the phosphoinositide 3 kinase (PI3K) pathway/the antiapoptotic kinase (AKT) pathway/the endothelial nitric oxide synthase (eNOS) pathway, the Erk1, the delta-like ligand (DII), the jagged (Jag)/NOTCH pathway, and the midkine regulatory cytokine signaling pathways.

Characteristics of Spontaneous Spinal Cord Infarction and Proposed Diagnostic Criteria

Importance

Spinal cord infarction (SCI) is often disabling, and the diagnosis can be challenging without an inciting event (eg, aortic surgery). Patients with a spontaneous SCI are often misdiagnosed as having transverse myelitis. Diagnostic criteria for SCI are lacking, hindering clinical care and research.

Objective

To describe the characteristics of spontaneous SCI and propose diagnostic criteria.

Design, Setting, and Participants

An institution-based search tool was used to identify patients evaluated at Mayo Clinic, Rochester, Minnesota, from January 1997 to December 2017 with a spontaneous SCI. Patients provided written consent to use their records for research. Participants were 18 years and older with a diagnosis of spontaneous SCI (n = 133), and controls were selected from a database of alternative myelopathy etiologies for validation of the proposed diagnostic criteria (n = 280).

Main Outcomes and Measures

A descriptive analysis of SCI was performed and used to propose diagnostic criteria, and the criteria were validated.

Results

Of 133 included patients with a spontaneous SCI, the median (interquartile range) age at presentation was 60 (52-69) years, and 101 (76%) had vascular risk factors. Rapid onset of severe deficits reaching nadir within 12 hours was typical (102 [77%]); some had a stuttering decline (31 [23%]). Sensory loss occurred in 126 patients (95%), selectively affecting pain/temperature in 49 (39%). Initial magnetic resonance imaging (MRI) spine results were normal in 30 patients (24%). Characteristic MRI T2-hyperintense patterns included owl eyes (82 [65%]) and pencil-like hyperintensity (50 [40%]); gadolinium enhancement (37 of 96 [39%]) was often linear and located in the anterior gray matter. Confirmatory MRI findings included diffusion-weighted imaging/apparent diffusion coefficient restriction (19 of 29 [67%]), adjacent dissection/occlusion (16 of 82 [20%]), and vertebral body infarction (11 [9%]). Cerebrospinal fluid showed mild inflammation in 7 of 89 patients (8%). Diagnostic criteria was proposed for definite, probable, and possible SCI of periprocedural and spontaneous onset. In the validation cohort (n = 280), 9 patients (3%) met criteria for possible SCI, and none met criteria for probable SCI.

Conclusions and Relevance

This large series of spontaneous SCIs provides clinical, laboratory, and MRI clues to SCI diagnosis. The diagnostic criteria proposed here will aid clinicians in making the correct diagnosis and ideally improve future care for patients with SCI. The validation of these criteria supports their utility in the evaluation of acute myelopathy.

Treatment Outcomes and Risk Factors for In-Hospital Mortality in Patients with Acute Aortic Occlusion

Purpose

The aims of the present study are to determine the outcomes after acute aortic occlusion (AAO) and analyze the risk factors for in-hospital mortality.

Materials and Methods

We retrospectively analyzed 24 patients who were diagnosed with AAO from 2002 to 2017 in our registered data. Demographic and radiologic characteristics of AAOs were retrospectively collected. Perioperative treatment outcomes including in-hospital mortality were also assessed and the risk factors of in-hospital mortality were analyzed.

Results

The median symptom duration was 21 hours. Five patients had complete paraplegia and 10 patients (41.7%) were initially evaluated for central nervous system disorders instead of acute arterial occlusion. The etiology was determined to be aortoiliac thrombosis in 17 patients (70.8%) and embolic occlusion in 7. Surgical revascularization was performed in 23 patients, and one patient did not receive any treatment. The overall in-hospital mortality was 34.8% (8/23) and 30-day mortality was 26.1%. In the univariate analysis, age (P=0.040), preoperative renal insufficiency (serum creatinine over 1.5 mg/dL at the time of presentation) (P=0.008), postoperative acute kidney injury (need for dialysis or an increase in serum creatinine of >50.0% within 48 hours) (P=0.006), combined external iliac artery occlusion (P=0.019) and combined bilateral internal iliac artery occlusion (P=0.039) were associated with in-hospital mortality.

Conclusion

A substantial number of AAO patients were initially evaluated for a central nervous system lesion, which led to a delay in diagnosis. Thus, vascular examinations should always be performed in every patient presenting with lower limb neurologic deficits. Age, perioperative renal function, and combined iliac artery occlusion were associated with the prognosis of AAOs.

Fiber-optic Monitoring of Spinal Cord Hemodynamics in Experimental Aortic Occlusion

BACKGROUND

Spinal cord ischemia occurs frequently during thoracic aneurysm repair. Current methods based on electrophysiology techniques to detect ischemia are indirect, non-specific, and temporally slow. In this article, the authors report the testing of a spinal cord blood flow and oxygenation monitor, based on diffuse correlation and optical spectroscopies, during aortic occlusion in a sheep model.

METHODS

Testing was carried out in 16 Dorset sheep. Sensitivity in detecting spinal cord blood flow and oxygenation changes during aortic occlusion, pharmacologically induced hypotension and hypertension, and physiologically induced hypoxia/hypercarbia was assessed. Accuracy of the diffuse correlation spectroscopy measurements was determined via comparison with microsphere blood flow measurements. Precision was assessed through repeated measurements in response to pharmacologic interventions.

RESULTS

The fiber-optic probe can be placed percutaneously and is capable of continuously measuring spinal cord blood flow and oxygenation preoperatively, intraoperatively, and postoperatively. The device is sensitive to spinal cord blood flow and oxygenation changes associated with aortic occlusion, immediately detecting a decrease in blood flow (-65 ± 32%; n = 32) and blood oxygenation (-17 ± 13%, n = 11) in 100% of trials. Comparison of spinal cord blood flow measurements by the device with microsphere measurements led to a correlation of R = 0.49, P < 0.01, and the within-sheep coefficient of variation was 9.69%. Finally, diffuse correlation spectroscopy is temporally more sensitive to ischemic interventions than motor-evoked potentials.

CONCLUSION

The first-generation spinal fiber-optic monitoring device offers a novel and potentially important step forward in the monitoring of spinal cord ischemia.

Thoracoabdominal aortic aneurysm repair: current endovascular perspectives

Thoracoabdominal aneurysms account for roughly 3% of identified aneurysms annually in the United States. Advancements in endovascular techniques and devices have broadened their application to these complex surgical problems. This paper will focus on the current state of endovascular thoracoabdominal aneurysm repair, including specific considerations in patient selection, operative planning, and perioperative complications. Both total endovascular and hybrid options will be considered.

Liverpool Aortic Surgery Symposium V: New Frontiers in Aortic Disease and Surgery

Aortic aneurysm disease is a complex condition that requires a multidisciplinary approach in management. The innovation and collaboration among vascular surgery, cardiothoracic surgery, interventional radiology, and other related specialties is essential for progress in the management of aortic aneurysms. The Fifth Liverpool Aortic Surgery Symposium that was held in May 2013 aimed at bringing national and international experts from across the United Kingdom and the globe to deliver their thoughts, applications, and advances in aortic and vascular surgery. In this report, we present a selected short synopsis of the key topics presented at this symposium.