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

A direct aorta to segmental artery bypass for prevention of spinal cord ischemia after endovascular aortic repair

Spinal cord ischemia remains a persistent challenge after endovascular aortic aneurysm repair. We present a novel direct aorta to segmental artery bypass before aneurysm repair in a 64-year-old woman presenting with an enlarging aneurysm following dissection. Through an eighth intercostal incision, a polyester graft was sewn into the aorta using pledgeted sutures. An entry needle was used to directly access the previously treated aortic segment, and the opening was stented and angioplasty was performed to create inflow. Anastomoses were performed to a prominent left T10 segmental artery with a harvested saphenous vein. The patient remained neurologically intact postoperatively and the 1-month follow-up angiography demonstrated bypass patency.

Teaching vascular anatomy: the anatomy we know, the anatomy we see or the anatomy we need?

PURPOSE

This article presents the evolution of the subject of vascular anatomy and discusses the associated clinical applicability.

METHODS

Clinically-driven surgical examples met in our everyday practice were used to depict characteristic anatomical paradoxes raised by the inconsistencies between classical anatomical perception, current imaging modalities and modern surgical techniques.

RESULTS

Consequent anatomy-driven modifications of medical devices comprise a characteristic example of the vivid, modern and meaningful role that anatomy can have on clinical decision-making and improvement of technical and clinical success. Clinical experience provides a feedback that shifts the focus of anatomic research towards new fields of interest, such as the role of arterial collateral networks as therapeutic targets. The clinical feedback brings into light queries and issues where traditional anatomical answers may be vague and inadequate to apply, thereby necessitating further research, refinement and reevaluation.

CONCLUSION

While the traditional teaching of vascular anatomy is based on information and illustrations derived from dissection and prosection courses, the development of modern imaging technologies applied in large numbers of living patients and application of minimally invasive techniques challenge our understanding of what should be perceived as fixed and permanent. Moreover, the recently introduced evidence-based philosophy in anatomy elaborate more robust data which not only update, validate and enrich the existing knowledge of anatomical variations but also enable subgroup analyses with respect to race, age and sex, identifying specific anatomic features associated with a significant impact on patient treatment.

Variations in the origin of the anterior spinal artery in a Colombian population sample

Based on most neuroanatomical descriptions, the anterior spinal artery (ASA) originates from two small vessels of the vertebral arteries, which are anastomosed just before forming the basilar artery. This study aimed to determine and quantify the possible variants of the origin of the ASA and its trajectory in samples of human brain stems. Male brain stems with the superior portion of the spinal cord until myelomera C3 of 23 adult human, and no evident morphological alterations were selected. The brain stems were collected for three years and fixed in a 10% formalin solution at the Anatomy Laboratory of the Universidad de Caldas (Colombia). Five samples (21.7%) had variations in the origin and trajectory of the anterior spinal artery. The variations in the origin of the ASA could generate morphofunctional advantages instead of leading to complications. That is the case when there are two anterior spinal arteries since it would increase tissue perfusion, thus protecting part of the spinal cord from ischemic pathologies. It is essential to consider the variations that may exist in the supply of the anterior region of the spinal cord for clinical and surgical assessments due to variations in its supplied territory.

Artery of Adamkiewicz

This article reviews the case of a 65-year-old patient with unstable L1 fracture after trauma. The fracture was treated via balloon kyphoplasty, shortly after which the patient developed shortness of breath and severe headache. Subsequent computed tomography (CT) of the head revealed subarachnoid hemorrhage. CT angiography did not reveal any intracranial aneurysms or arteriovenous malformations. A massive spinal subdural hematoma, which caused the patient to develop right leg paresis and hip joint weakness with grade 2-3, was found during magnetic resonance imaging (MRI). The hematoma was removed using multi-stage laminectomy Th5-L3. A follow-up MRI showed no pathological findings. Due to the unusual findings, spinal angiography was performed, revealing the artery of Adamkiewicz (A. radicularis magna, AKA) on the L1 level on the right side. Control CT showed a suboptimal insertion of the needle into the right pedicle, which caused the injury of the artery. AKA is present in the majority of the population, and surgical attention should be paid to avoid injury. Surgeons operating on the thoracolumbar spinal cord should have a thorough understanding of the anatomical features and surgical implications of this artery.

Frozen Elephant Trunk: Technical Overview and Our Experience with a Patient-Tailored Approach

Ever since the first hybrid prosthesis was used for a total aortic arch replacement, many other techniques have been developed to comply with the need for the treatment of a wide spectrum of patients and their clinical pictures. We hereby provide an overview of the most popular surgical techniques to perform a frozen elephant trunk, including our tailored approach revolving around the antegrade deployment of a Gore C-TAG endovascular stent graft sutured to a four-branched vascular prosthesis. This technique was applied to three cases of acute type A aortic dissection. Although our small series of patients consists of acute aortic dissections only, this technique could be applied to any other aortic arch pathology, such as chronic dissections or aneurysms. Moreover, we believe that, because of the individually tailored approach and widespread availability of the necessary materials, this technique can reveal itself useful in many different operative scenarios.

To Inadvertent Vascular Placement of an Intrathecal Catheter: A Case Report

Intrathecal drug delivery systems (IDDS) are a treatment option for patients with chronic nonmalignant pain and cancer pain. In this case report, we describe a patient in whom an intrathecal catheter was implanted into a blood vessel rather than into the subarachnoid cavity. A contrast agent was administered, and digital subtraction angiography (DSA) imaging suggested that the catheter was inserted into a blood vessel. The anterior spinal arteries and veins were verified on the ventral side of the spinal cord without interruption. To our knowledge, this is the first report of implantation of an IDDS catheter into a blood vessel.

Application of Controlled Hypotension During Surgery for Spinal Metastasis

With advances in tumor treatment, metastasis to bone is increasing, and surgery has become the only choice for most terminal patients. However, spinal surgery has a high risk and is prone to heavy bleeding. Controlled hypotension during surgery has outstanding advantages in reducing intraoperative bleeding and ensuring a clear field of vision, thus avoiding damage to important nerves and vessels. Antihypertensive drugs should be carefully selected after considering the patient's age, different diseases, etc, and a single or combined regimen can be used. Hypotension also inevitably leads to a decrease in perfusion of important organs, so the threshold of hypotension and the maintenance time of hypotension should be strictly limited, and the monitoring of important organs during the operation is particularly important. Information such as blood perfusion, blood oxygen saturation, cardiac output, and neurophysiological conduction potential changes should be obtained in a timely fashion, which will help to reduce the risk of hypotension. In short, when applying controlled hypotension, it is necessary to choose an appropriate threshold and duration, and appropriate monitoring should be conducted during the operation to ensure the safety of the patient.

Role of historical and procedural staging during elective fenestrated and branched endovascular treatment of extensive thoracoabdominal aortic aneurysms

OBJECTIVE

Procedural staging is often performed to reduce the incidence of spinal cord ischemia (SCI) during endovascular treatment of extensive thoracoabdominal aortic aneurysms (TAAAs). However, its role in the case of previous thoracic or infrarenal aortic repair (historical staging) has been controversial. In the present study, we evaluated the SCI rates when procedural staging was routinely used and studied its potential benefits when previous aortic repairs had already been performed.

METHODS

The data from patients treated electively with fenestrated/branched endovascular aortic repair for extent I, II, III, and V TAAAs were retrieved from a multicenter registry (four high-volume national teaching hospitals) and analyzed. The primary endpoint was the rate of SCI and its association with preoperative and postoperative variables, including historical staging, procedural staging, and an impaired collateral network (subclavian or hypogastric stenosis >75% per occlusion). Variables were defined in accordance with the Society for Vascular Surgery reporting standards. A logistic regression model with stepwise selection was used to identify the predictors of SCI.

RESULTS

A total of 240 patients (76% male; median age, 73 years) were analyzed. Of the 240 patients, 43 (18%) had presented with an impaired collateral network, 136 (57%) had had historical staging, and 157 (65%) had received procedural staging. Preoperative spinal fluid cerebrospinal drainage was performed in 130 patients (54%). Permanent grade 3 SCI was observed in 13 patients (5%) and was negatively affected by both an impaired collateral network (odds ratio [OR], 17.3; 95% confidence interval [CI], 1.7-176; P = .016) and the presence of bilateral iliac occlusive disease (OR, 10.1; 95% CI, 1.1-98.3; P = .046). Both historical (OR, 0.02; 95% CI, 0.001-0.46; P = .014) and procedural (OR, 0.01; 95% CI, 0.02-0.7; P = .019) staging mitigated the permanent SCI rates. The need for postoperative transfusions (OR, 1.4; 95% CI, 1.1-1.8; P = .014) and the occurrence of postoperative renal complications (OR, 6.5; 95% CI, 1.2-35.0; P < .001) were associated with the development of SCI. Among the patients with historical staging, no further benefit from procedural staging was observed (SCI with procedural staging, 1%; vs no staging, 2%; P = NS).

CONCLUSIONS

For patients with extensive TAAAs treated with fenestrated/branched endovascular aortic repair, both historical and planned procedural staging were associated with reduced permanent SCI rates. However, no additional benefit was observed when procedural staging was performed in patients with historical staging and an intact collateral network. The protective role of preoperative cerebrospinal fluid drainage placement requires further investigation.

Hemodynamic Patterns of Spinal Cord Perfusion in Thoracoabdominal Aortic Aneurysm Repair

Paraplegia in aortic surgery is due to its impact on spinal cord perfusion whose hemodynamic patterns (SCPHP) are not clearly defined. Detailed morphological analysis of vascular network and collateral network modifications within Monro-Kellie postulate due to the fixed theca confines was performed to identify SCPHP. SCPHP may begin with intraspinal "backflow" (I-BF), that is, hemorrhage from anterior and posterior spinal arteries, backward via the connected anterior and posterior radicular medullary arteries, through the increasing diameter and decreasing resistance of segmental arteries (SAs), off their aortic orifices outside vascular network at 0 operative field pressure. The I-BF blood bypasses both intra- and extraspinal capillary networks and causes depressurization (0 diastolic pressure) and full ischemia of dependent spinal cord. When the occlusion of those SAs orifices arrests I-BF, the hemodynamic pattern of intraspinal "steal" (I-S) may take place. The formerly I-BF blood, in fact, is now variably shared between the fraction maintained in its physiological intraspinal network and that keeping flowing as I-S through the extraspinal capillary network. I-S is, however, counteracted by the extraspinal "steal" from the connected mammary/paraspinous-independent extraspinal feeders, all physically competing for the same room left by the missed physiological SA direct aortic blood inflow. Steal phenomenon evolves within the 120-hour time frame of CNm, whose intraspinal anatomical changes may offer the physical basis within the Monro-Kelly postulate, respectively of the intraoperative and postoperative paraplegia. The current procedures could not prevent the unphysiological SCPHP but awareness of details of their various features may offer the basis for improvements tailored, to the adopted intra- and postoperative procedures.

Acute Myelopathy: Vascular and Infectious Diseases

Vascular and infectious causes are rare but important causes of spinal cord injury. High suspicion for these processes is necessary, as symptoms may progress over hours to days, resulting in delayed presentation and diagnosis and worse outcomes. History and clinical examination findings can assist with localization of the affected vascular territory and spinal level, which will assist with focusing spinal imaging. Open and/or endovascular surgical management depends on the associated vascular abnormality. Infectious myelopathy treatment consists of targeted antimicrobial therapy when possible, infectious source control, and again, close monitoring for systemic complications.

Selective Angiography to Detect Anterior Spinal Artery Stenosis in Thoracic Ossification of the Posterior Longitudinal Ligament

Study Design

Single-center prospective study.

Purpose

To investigate anterior spinal artery (ASA) status using preoperative selective angiography in patients undergoing surgery for thoracic ossification of the posterior longitudinal ligament (T-OPLL).

Overview of Literature

Surgery for T-OPLL has a high risk of neurological complications, which might be associated with insufficient spinal cord blood flow.

Methods

This study prospectively examined nine T-OPLL patients who underwent posterior thoracic decompression with kyphosis correction and instrumented fusion at Hamamatsu University School of Medicine between 2017 and 2019. All underwent preoperative selective angiography to detect and evaluate the Adamkiewicz artery and ASA. Intraoperative neuromonitoring and Doppler ultrasonography were performed to analyze neurological complications and spinal cord blood flow.

Results

All nine patients showed ASA stenosis in the area of T-OPLL. In all patients, the Adamkiewicz artery was located between T7 and L2 and the area of ASA stenosis corresponded to the level of T-OPLL and greatest spinal cord compression; intraoperative Doppler ultrasonography confirmed the ASA defect at the same spinal level. The number of spinal levels from the Adamkiewicz artery to the most compressive OPLL lesion was greater in the two patients who developed postoperative neurological deficit compared to those who did not (5.5 vs. 2.3, p=0.014).

Conclusions

This is the first study to report detection of ASA stenosis in patients with T-OPLL. Maintaining spinal cord blood flow is important in these patients to avoid neurological deterioration.

Spinal cord pathways

The spinal cord is the primary pathway of communication between the brain and peripheral nervous system. Knowledge of the spinal cord anatomy and recognition of typical common spinal cord syndromes are important as many of these diseases have a predilection for targeting specific areas or tracts within the spinal cord.

3D Digital Anatomic Angioarchitecture of the Rat Spinal Cord: A Synchrotron Radiation Micro-CT Study

Comprehensive analysis of 3D angioarchitecture within the intact rat spinal cord remains technically challenging due to its sophisticated anatomical properties. In this study, we aim to present a framework for ultrahigh-resolution digitalized mapping of the normal rat spinal cord angioarchitecture and to determine the physiological parameters using synchrotron radiation micro-CT (SRμCT). Male SD rats were used in this ex vivo study. After a proportional mixture of contrast agents perfusion, the intact spinal cord covered the cervical spinal from the upper of the 1st cervical vertebra to the 5th lumbar vertebra was harvested and cut into proper lengths within three distinct regions: Cervical 3–5 levels, Thoracic 10–12 levels, Lumbar 3–5 levels spinal cord and examined using SRμCT. This method enabled the replication of the complicated microvasculature network of the normal rat spinal cord at the ultrahigh-resolution level, allowing for the precise quantitative analysis of the vascular morphological difference among cervical, thoracic and lumbar spinal cord in a 3D manner. Apart from a series of delicate 3D digital anatomical maps of the rat spinal cord angioarchitecture ranging from the cervical and thoracic to the lumbar spinal cord were presented, the 3D reconstruction data of SRμCT made the 3D printing of the spinal cord targeted selected microvasculature reality, that possibly provided deep insight into the nature and role of spinal cord intricate angioarchitecture. Our data proposed a new approach to outline systematic visual and quantitative evaluations on the 3D arrangement of the entire hierarchical microvasculature of the normal rat spinal cord at ultrahigh resolution. The technique may have great potential and become useful for future research on the poorly understood nature and function of the neurovascular interaction, particularly to investigate their pathology changes in various models of neurovascular disease.

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.

Preoperative CT Angiography Informs Instrumentation in Anterior Spine Surgery for Idiopathic Scoliosis

The objective of this study is to evaluate whether the artery of Adamkiewicz localization with preoperative CT angiography influences anterior spinal instrumentation.

Methods

Children with idiopathic scoliosis who underwent anterior instrumentation and with a preoperative CT angiography were evaluated retrospectively. Data included curve type, artery of Adamkiewicz level/laterality, surgical approach laterality, number of instrumented levels and segmental vessels ligated, intraoperative neuromonitoring changes, and postoperative neural complications.

Results

Thirty-nine girls and eight boys (mean age 12 years [6.7 to 16.8 years]) were analyzed. Instrumented curves indicate 28 thoracic, 14 thoracolumbar, and seven double major. The artery of Adamkiewicz: T6 (left-1), T8 (left-1), T9 (left-4/right-2), T10 (left-11/right-4), T11 (left-4/right-4), T12 (left-1/right-2), L1 (left-2/right-1), and L2 (left-3/right-2). Four had bilateral dominant segmentals, whereas in nine patients, none was identified. T10 (32%) and left side (57%) were most frequent. On average, 7.1 (4 to 11) segmentals were ligated per case (total 355). Dominant vessels were ipsilateral to/within instrumentation levels in 30%.

Discussion

In children with idiopathic scoliosis who underwent anterior instrumentation, the artery of Adamkiewicz was identified on the left in >50% and at T10 in 32%. In one-third of the patients, the artery was within intended surgical levels and resulted in instrumentation modification.

Society for Vascular Surgery (SVS) and Society of Thoracic Surgeons (STS) Reporting Standards for Type B Aortic Dissections

This Society for Vascular Surgery/Society of Thoracic Surgeons (SVS/STS) document illustrates and defines the overall nomenclature associated with type B aortic dissection. The contents describe a new classification system for practical use and reporting that includes the aortic arch. Chronicity of aortic dissection is also defined along with nomenclature in patients with prior aortic repair and other aortic pathologic processes, such as intramural hematoma and penetrating atherosclerotic ulcer. Complicated vs uncomplicated dissections are clearly defined with a new high-risk grouping that will undoubtedly grow in reporting and controversy. Follow-up criteria are also discussed with nomenclature for false lumen status in addition to measurement criteria and definitions of aortic remodeling. Overall, the document provides a facile framework of language that will allow more granular discussions and reporting of aortic dissection in the future.

Artery of Adamkiewicz: a meta-analysis of anatomical characteristics

PURPOSE

The artery of Adamkiewicz (AKA) provides the major blood supply to the anterior thoracolumbar spinal cord and iatrogenic injury or inadequate reconstruction of this vessel during vascular and endovascular surgery can result in postoperative neurological deficit due to spinal cord ischemia. The aim of this study was to provide comprehensive data on the prevalence and anatomical characteristics of the AKA.

METHODS

An extensive search was conducted through the major electronic databases to identify eligible articles. Data extracted included study type, prevalence of the AKA, gender, number of AKA per patient, laterality, origin based on vertebral level, side of origin, morphometric data, and ethnicity subgroups.

RESULTS

A total of 60 studies (n = 5437 subjects) were included in the meta-analysis. Our main findings revealed that the AKA was present in 84.6% of the population, and patients most frequently had a single AKA (87.4%) on the left side (76.6%) originating between T8 and L1 (89%).

CONCLUSION

As an AKA is present in the majority of the population, caution should be taken during vascular and endovascular surgical procedures to avoid injury or ensure proper reconstruction. All surgeons operating in the thoracolumbar spinal cord should have a thorough understanding of the anatomical characteristics and surgical implications of an AKA.

A 3D subject-specific model of the spinal subarachnoid space with anatomically realistic ventral and dorsal spinal cord nerve rootlets

BACKGROUND

The spinal subarachnoid space (SSS) has a complex 3D fluid-filled geometry with multiple levels of anatomic complexity, the most salient features being the spinal cord and dorsal and ventral nerve rootlets. An accurate anthropomorphic representation of these features is needed for development of in vitro and numerical models of cerebrospinal fluid (CSF) dynamics that can be used to inform and optimize CSF-based therapeutics.

METHODS

A subject-specific 3D model of the SSS was constructed based on high-resolution anatomic MRI. An expert operator completed manual segmentation of the CSF space with detailed consideration of the anatomy. 31 pairs of semi-idealized dorsal and ventral nerve rootlets (NR) were added to the model based on anatomic reference to the magnetic resonance (MR) imaging and cadaveric measurements in the literature. Key design criteria for each NR pair included the radicular line, descending angle, number of NR, attachment location along the spinal cord and exit through the dura mater. Model simplification and smoothing was performed to produce a final model with minimum vertices while maintaining minimum error between the original segmentation and final design. Final model geometry and hydrodynamics were characterized in terms of axial distribution of Reynolds number, Womersley number, hydraulic diameter, cross-sectional area and perimeter.

RESULTS

The final model had a total of 139,901 vertices with a total CSF volume within the SSS of 97.3 cm³. Volume of the dura mater, spinal cord and NR was 123.1, 19.9 and 5.8 cm³. Surface area of these features was 318.52, 112.2 and 232.1 cm² respectively. Maximum Reynolds number was 174.9 and average Womersley number was 9.6, likely indicating presence of a laminar inertia-dominated oscillatory CSF flow field.

CONCLUSIONS

This study details an anatomically realistic anthropomorphic 3D model of the SSS based on high-resolution MR imaging of a healthy human adult female. The model is provided for re-use under the Creative Commons Attribution-ShareAlike 4.0 International license (CC BY-SA 4.0) and can be used as a tool for development of in vitro and numerical models of CSF dynamics for design and optimization of intrathecal therapeutics.

Spinal Cord Infarcts: Risk Factors, Management, and Prognosis

OPINION STATEMENT

There are no standard guidelines for treatment of spinal cord ischemia due to how rare it is and the diverse etiology and presentations involved. In addition, to date, there have been no large clinical trials examining ideal pharmacologic treatment options for spinal cord infarct. In our practice, we rely on hemodynamic augmentation initiated as soon as possible. Otherwise, treatment is usually geared towards the etiology of spinal cord ischemia. For instance, spinal cord ischemia occurring after aortic aneurysmal repair may improve with CSF drainage through a lumbar catheter in the periprocedural setting. Vertebral artery dissection should be treated with antithrombotics. If no clear etiology is found and there is evidence of atherosclerosis in other vascular beds, then management is focused on risk factor modification with blood pressure and glucose control, statins, and antithrombotics.

Predictors of Adamkiewicz artery and anterior spinal artery detection through computerized tomographic angiography

Background:

The detection of the Adamkiewicz artery and the anterior spinal artery has been associated with the ability to prevent adverse spinal cord outcomes after aortic surgical procedures. Yet, to our knowledge, no previous studies have attempted to use modern predictive models to identify the most important variables in determining artery detectability.

Aims:

To develop a model to predict the odds of visualizing the Adamkiewicz artery or anterior spinal artery in patients undergoing computerized tomographic angiography.

Methods:

We conducted a prospective, cross-sectional study. Outcomes of interest were the non-detection of the Adamkiewicz artery and anterior spinal artery, and their corresponding level of origin. Axial images were inspected in high definition in search of two dense spots characterizing the Adamkiewicz artery and anterior spinal artery. A multiplanar three-dimensional reconstruction was then performed using the OsiriX® software.

Results:

A total of 110 participants were part of this analysis. When evaluating risks for the Adamkiewicz artery being undetectable, significant factors could be classified into three broad categories: risk factors for arterial disease, established arterial disease, and obesity. Factors in the former category included metabolic syndrome, hypertension, and smoking status, while factors in the arterial disease included descending aortic aneurysm, mural thrombi, aortic aneurysm without a dissection, and aortic disease in general. In relation to anterior spinal artery not being detectable, significant risk factors included hypertension, smoking status, and metabolic syndrome, while those associated with arterial disease involved aortic disease and arterial thrombi. When evaluating the importance of individual clinical factors, the presence of higher body mass index was the single most important risk factor.

Conclusion:

Arterial disease, established arterial disease, and increased body mass index are risk factors in the detection of Adamkiewicz artery and anterior spinal artery. Specific diagnostic protocols should be in place for patients with these underlying conditions, thus enhancing the likelihood of detection when the Adamkiewicz artery is indeed present.

Spinal cord ischemia in Scheuermann disease: A report of three cases

BACKGROUND

Neurological complications in Scheuermann's disease are rare but serious.

CASE REPORTS

We report three cases of severe neurological deficit due to medullar ischemia attributable to the compression of a radiculomedullar artery by thoracic (two cases) and lumbar (one case) disc herniations associated with Scheuermann's disease. They were not treated surgically because of the absence of direct spinal cord compression or definitive spinal cord ischemia. Those young patients still have severe neurological damage. An earlier management could have prevented them.

CONCLUSION

When doubting about any compressive sign, MRI should be performed with diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) sequences in emergency.

Extraforaminal needle tip position reduces risk of intravascular injection in CT-fluoroscopic lumbar transforaminal epidural steroid injections

BACKGROUND

Lumbar transforaminal epidural steroid injection is a common and effective tool for managing lumbar radicular pain, although accidental intravascular injection can rarely result in paralysis. The purpose of this study is to determine the safest needle tip position for computed tomography (CT)-guided lumbar transforaminal epidural steroid injections as determined by incidence of intravascular injection.

METHODS

Three radiologists, in consensus, reviewed procedural imaging for consecutive CT-fluoroscopic lumbar transforaminal epidural steroid injections performed during a 16-month period. Intravascular injections were identified and categorized by needle tip position, vessel type injected, intravascular injection volume and procedural phase containing the intravascular injection. Pearson chi-square and logistic regression testing were used to assess differences between groups, as appropriate.

RESULTS

Intravascular injections occurred in 9% (52/606) of injections. The intravascular injection rate was significantly lower (P<0.001) for extraforaminal needle position (0%, 0/109) compared to junctional (8%, 27/319) and foraminal (14%, 25/178) needle tip positions. Of the intravascular injections, 4% (2/52) were likely arterial, 35% (18/52) were likely venous, and 62% (32/52) were indeterminate for vessel type injected. 46% (24/52) of intravascular injections were large volume, 33% (17/52) were small volume, and 21% (11/52) were trace volume. 56% (29/52) of intravascular injections occurred with the contrast trial dose, 29% (15/52) with the steroid/analgesic cocktail, and 15% (8/52) with both.

CONCLUSIONS

An extraforaminal needle position for CT-fluoroscopic lumbar transforaminal epidural steroid injections decreases the risk of intravascular injection and therefore may be safer than other needle tip positions.

Confocal raman microspectral imaging of ex vivo human spinal cord tissue

Confocal Raman microspectral imaging (CRMI) provides a versatile tool to illustrate the biochemical nature and structure of biological tissue without introducing any external labels. In this work, a precise correlation was established between the biochemical profile and histological architecture of ex vivo human spinal cord tissue by using CRMI with 633nm excitation. After precisely linking the spectral features to the chemical constituents, much information about the molecular composition of both gray and white matter were revealed. Two-dimensional Raman images were generated by integrating the intensities of the characteristic Raman bands in the area of the intermediate column and ventral horn. K-mean cluster analysis was further applied to visualize the underlying morphological basis of spinal cord tissue by chemical component types and their distribution pattern. Lipid-rich white matter could be visually distinguished from gray matter considering a CH2 bending/scissoring band at 1445cm(-1) and an amide III band at 1250cm(-1). Meanwhile, the formation and distribution pattern of perineuronal nets (PNNs) in the scanning area was validated by the integration of saccharides (617cm(-1)) and amide III bands. Moreover, the heme profile indicated a higher degree of vascularization in gray matter. All of the results obtained testified to the possibility that gray matter could be more susceptible to spinal cord injury (SCI) because of capillary network distribution and glycosaminoglycans (GAGs) aggregation. These findings are important for interpreting the morphological specificity of human spinal cord tissue, and also for studying the molecular basis of SCI.

Lumbar artery injury from which the Adamkiewicz artery originated associated with lumbar spine injury: successfully treated by transcatheter arterial embolization

PURPOSE

Lumbar artery injury associated with lumbar spine injury can be a cause of shock leading to life-threatening condition. The Adamkiewicz artery often bifurcates from a lumbar spine or an intercostal artery at the thoracolumbar junction, where spine injury most commonly occurs. However, in emergency transcatheter arterial embolization for lumbar artery injury, hemostasis has priority and blood supply to the Adamkiewicz artery is not frequently confirmed. The aim of this report is to present the case of lumbar spine injury with lumbar artery injury from which the Adamkiewicz artery bifurcated.

METHODS

Retrospective description of a case.

RESULTS

A 58-year-old man was pinned under about 300-kg steel container that fell on his back. He was transported to our hospital presented with hemorrhagic shock. Contrast-enhanced computed tomography demonstrated L1-2 flexion-distraction injury and the left psoas major muscle swelling with extravasation of contrast medium, which suspected lumbar artery injury. Emergency angiography demonstrated the bilateral 2nd lumbar artery injury. Likewise, the Adamkiewicz artery originated from the distal part of the left 2nd lumbar artery. Fortunately, selective angiography of the left 1st lumbar artery depicted collateral circulation to the Adamkiewicz artery. Embolization of the bilateral 2nd lumbar artery was performed and massive hemorrhage was controlled successfully without spinal cord ischemia.

CONCLUSIONS

Close attention must be paid to lumbar artery injury in the management of patients with lumbar spine injury. Once lumbar artery injury is found, transcatheter arterial embolization can be the choice of the treatment with careful attention to the Adamkiewicz artery.

The lumbar arteries and veins: Quantification of variable anatomical positioning with application to retroperitoneal surgery

The lumbar arteries and veins are segmentally arranged vessels in the abdomen that supply the vertebrae and posterior abdominal/paravertebral muscles. Recent studies have indicated that these vessels have a tendency to vary from the classical description of bilateral pairing. The objective of this study was to more accurately characterize the anatomy of the lumbar vessels through the dissection of 22 cadaveric specimens and examination of 41 patients' computed tomography angiography scans. The positions of the lumbar vessels were measured in reference to the bifurcation/confluence of the common iliac arteries/veins. In 22 cadaveric specimens, the course of the lumbar veins was dissected to the psoas major muscle to characterize venous tributaries. Our results indicate that the lumbar veins were rarely paired, segmentally diverged closer to the iliocaval confluence, and preferentially drained into the left side of the IVC. Several types of lumbar veins were additionally characterized based on their consistent coursing patterns. In contrast, the lumbar arteries exhibited pairing, and these successive pairs were found to be equally spaced along the length of the infrarenal abdominal aorta. In specimens where the median sacral artery and 4th lumbar artery pair arose from a trifurcating common trunk, the positions of the 3rd and 4th lumbar arteries were significantly inferior (P < 0.05) compared to those with independent median sacral arteries. Clinically, proper management of the anatomical patterns described in this study may be pivotal in reducing the incidence of intraoperative damage to the lumbar vessels, and may help in the treatment of vascular diseases.

Basic vascular neuroanatomy of the brain and spine: what the general interventional radiologist needs to know

This article is intended to provide a review of clinically relevant neurovascular anatomy. A solid understanding of the vascular anatomy of the brain and spine are essential for the safe and effective performance of neurointerventional radiology. Key concepts to master include collateral pathways and anastomoses between the external and internal carotid circulation, the Circle of Willis as a route to otherwise inaccessible intracranial vascular distributions, and the origin of spinal arterial blood supply. These concepts will be highlighted using clinical angiographic examples with discussion of relevant embryology and pathology as needed.

Evaluation of preoperative computed tomography angiography in association with conventional angiography versus computed tomography angiography only, in the endovascular treatment of aortic diseases

Objective To evaluate the association of conventional angiography (AG) with computed tomography angiography (CTA) as compared with CTA only, preoperatively, in the treatment of aortic diseases. Materials and Methods Retrospective study involving patients submitted to endovascular treatment of aortic diseases, in the period from January 2009 to July 2010, with use of preoperative CTA + conventional AG or CTA only. The patients were divided into two groups, namely: G1 – thoracic aortic diseases; and G2 – abdominal aortic diseases. G1 was subdivided into 1A (preoperative AG + CTA) and 1B (preoperative CTA). G2 was subdivided into 2C (CTA + AG) and 2D (CTA only). Results The authors evaluated 156 patients. In subgroups 1A and 1B, the rate of technical success was, respectively, 100% and 94.7% (p = 1.0); and the rate of therapeutic success was, respectively, 81% and 58% (p = 0.13). A higher number of complications were observed in subgroup 1B (p = 0.057). The accuracy in the calculation of the prosthesis was higher in subgroup 1A (p = 0.065). In their turn, the rate of technical success in subgroups 2C and 2D was, respectively, 92.3% and 98.6% (p = 0.17). The rate of therapeutic success was 73% and 98.6% (p = 0.79). Conclusion Preoperative conventional AG should be reserved for cases where CTA cannot provide all the information in the planning of a therapeutic intervention.

Intraforaminal location of thoracolumbar anterior medullary arteries

BACKGROUND

Transforaminal epidural steroid injection (TFESI) is a widely utilized interventional pain technique for radicular pain. Although the six o'clock position of the pedicle in the so-called "safe triangle" has been used as a target location, there have been a number of reported catastrophic complications of this procedure, including paraplegia. The mechanism of this has been attributed to the intravascular injection of steroids. The goal of this study was to examine the intraforaminal location of thoracolumbar medullary arteries which would help guide pain physicians in developing safer techniques and guidelines.

METHODS

Twenty-four (24) embalmed cadavers were dissected and examined for the presence and distribution of thoracolumbar anterior medullary arteries. Access to the anterior surface of the spinal cord was made via anterior corpectomy from C2 to S5. Each medullary artery's course was determined by dissection from its origin, the anterior spinal artery, through the intervertebral foramen. The foramen was subsequently opened in the coronal plane, and the intraforaminal location of the artery, its diameter, and its relation to other foraminal structures were examined and measured.

RESULTS

In the thoracolumbar foramina (T4-L2), 39 anterior medullary arteries were found, including 23 great medullary arteries (Adamkiewicz artery). One Adamkiewicz artery was found to be located in the left S2 foramen and was not included in the statistical analysis. Of the analyzed 39 anterior medullary arteries, 29 (74%) were located in the upper 1/3 of the foramen, 9 (23%) were located in the middle, and 1 (3%) artery was located in the lower 1/3. In relation to the dorsal root ganglion--ventral root complex, 21 (54%) arteries were located anterosuperiorly, 16 (41%) anteriorly, and 2 (5%) anteroinferiorly. The average intraforaminal artery diameter was 1.20 mm (0.84-1.91 mm). At thoracolumbar levels, the artery is almost always (92% ± 15%) located anterosuperior to the nerve. At typical thoracic levels, it is less often anterosuperior (38% ± 19%), but more often anterior to the nerve.

CONCLUSIONS

At thoracolumbar levels, if needles were to encounter an artery, they are most likely to do so if placed anterosuperior to the nerve. Encountering an artery anterosuperior to the nerve is less likely at typical thoracic levels, but the likelihood is far from negligible. Pain physicians should be cognizant of this when considering optimal needle placement during transforaminal epidural steroid injections.

Anterior surgery for adolescent idiopathic scoliosis

Anterior open scoliosis surgery using the dual rod system is a safe and rather effective procedure for the correction of scoliosis (50-60 %). Thoracic hypokyphosis and rib hump correction with open anterior rather than posterior instrumentation appear to be the better approaches, although the latter is somewhat controversial with current posterior vertebral column derotation devices. In patients with Risser grade 0, hyperkyphosis and adding-on may occur with anterior thoracic spine instrumentation. Anterior thoracoscopic instrumentation provides a similar correction (65 %) with good cosmetic outcomes, but it is associated with a rather high risk of instrumentation (pull-out, pseudoarthrosis) and pulmonary complications. Approximately 80 % of patients with adolescent idiopathic scoliosis (AIS) curves of >70° have restrictive lung disease or smaller than normal lung volumes. AIS patients undergoing anterior thoracotomy or anteroposterior surgery will demonstrate a significant decrease in percentage of predicted lung volumes during follow-up. The thoracoabdominal approach and thoracoscopic approach without thoracoplasty do not produce similar changes in detrimental lung volume. In patients with severe AIS (>90°), posterior-only surgery with TPS provides similar radiographic correction of the deformity (44 %) with better pulmonary function outcomes than anteroposterior surgery. Vascular spinal cord malfunction after segmental vessel ligation during anterior scoliosis surgery has been reported. Based on the current literature, the main indication for open anterior scoliosis instrumentation is Lenke 5C thoracolumbar or lumbar AIS curve with anterior instrumentation typically between T11 and L3.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Neurological complications of thoracic endovascular aortic repair

Thoracic endovascular aortic repair (TEVAR) has decreased the morbidity and mortality associated with open surgical repair of descending thoracic aortic diseases, but important complications unique to the procedure remain. Spinal cord ischemia and infarction is a recognized complication caused by endovascular coverage or injury to spinal cord collateral vessels. Stroke is a consequence of thromboembolism or coverage of aortic arch branch vessels with insufficient collateral circulation. Understanding the risk factors and the pathophysiology of neurological complications of TEVAR are important for the successful anesthetic and surgical management and treatment of patients undergoing endovascular procedures involving the thoracic aorta.