The Transdural Course of Radicular Spinal Cord Veins--A Microangiographical and Microscopical Study

Spinal dural and epidural fistulas: role of cone beam CT in diagnosis and treatment

Understanding normal spinal arterial and venous anatomy, and spinal vascular disease, is impossible without flow-based methods. Development of practical spinal angiography led to site-specific categorization of spinal vascular conditions, defined by the 'seat of disease' in relation to the cord and its covers. This enabled identification of targets for highly successful surgical and endovascular treatments, and guided interpretation of later cross-sectional imaging.Spinal dural and epidural arteriovenous fistulas represent the most common types of spinal shunts. Although etiology is debated, anatomy provides excellent pathophysiologic correlation. A spectrum of fistulas, from foramen magnum to the sacrum, is now well-characterized.Most recently, use of cone beam CT angiography has yielded new insights into normal and pathologic anatomy, including venous outflow. It provides unrivaled visualization of the fistula and its relationship with spinal cord vessels, and is the first practical method to study normal and pathologic spinal veins in vivo-with multiple implications for both safety and efficacy of treatments. We advocate consistent use of cone beam CT imaging in modern spinal fistula evaluation.The role of open surgery is likely to remain undiminished, with increasing availability and use of hybrid operating rooms for practical intraoperative angiography enhancing safety and efficacy of complex surgery.

On the spinal venous sinus of Alligator mississippiensis

The epidural space of the American alligator (Alligator mississippiensis) is largely filled by a continuous venous sinus. This venous sinus extends throughout the trunk and tail of the alligator, and is continuous with the dural sinuses surrounding the brain. Segmental spinal veins (sl) link the spinal venous sinus (vs) to the somatic and visceral venous drainage. Some of these sl, like the caudal head vein along the occipital plate of the skull, are enlarged, suggesting more functional linkage. No evidence of venous valves or external venous sphincters was found associated with the vs; the relative scarcity of smooth muscle in the venous wall of the sinus suggests limited physiological regulation. The proatlas (pr), which develops between the occipital plate and C1 in crocodylians, is shaped like a neural arch and is fused to the dorsal surface of the vs. The present study suggests that the pr may function to propel venous blood around the brain and spinal cord. The vs effectively encloses the spinal dura, creating a tube-within-a-tube system with the (smaller volume) spinal cerebrospinal fluid (CSF). Changes in venous blood pressure, as are likely during locomotion, would impact dural compliance and CSF pressure waves propagating along the spinal cord.

Factors Associated with Rapidly Deteriorating Myelopathy in Patients with Spinal Arteriovenous Shunts

Spinal arteriovenous (AV) shunts are rare conditions that sometimes present with myelopathy symptoms. The progression of the symptoms is usually gradual; however, some cases show rapid deterioration. We retrospectively investigated the factors that induced the rapid deterioration of myelopathy symptoms in patients with spinal AV shunts. We treated 33 patients with myelopathy with spinal AV shunts at our institutions, eight of whom experienced rapid deterioration (within 24 hours: 24.2%). Of these, three were related to the body movement or particular postures associated with playing golf, 30 minutes of Japanese straight sitting, and massage care. One patient showed deterioration after embolization for a tracheal aneurysm. The remaining four patients received steroid pulse therapy (high-dose steroid infusion) shortly before the rapid deterioration. These symptoms stopped progressing after cessation of steroid use. While positional or physical factors contributing to myelopathy deterioration might exist, we could not identify specific factors in this study. Nevertheless, rapid deterioration was frequently observed after high-dose steroid use. We must take care not to administer high-dose steroids for myelopathy caused by spinal AV shunt disease.

Pathology and Protein Changes of the Spinal Dural Arteriovenous Fistula Arterial Draining Vein Under Sustained High Vascular Pressure

Object: Spinal dural arteriovenous fistula (SDAVF) is the most common spinal vascular shunt lesion. Although pathological changes in the SDAVF draining vein (SDAVF-DV) have been elucidated, protein changes remain enigmatic. We investigated the pathology and protein changes in the SDAVF-DV under sustained high vascular pressure.

Methods: Three SDAVF-DV samples were compared with superficial temporal artery (STA) and superficial temporal vein (STV) samples as controls. Vascular structure was revealed by hematoxylin and eosin (H&E) and Masson staining; and cell distribution, extracellular matrix, and inflammation infiltration were observed by immunohistochemistry. Label-free quantitative proteomics was performed, and the peptide mixture was fractionated and analyzed by liquid chromatography–tandem mass spectrometry (LC-MS/MS) to identify differentially expressed proteins. Bioinformatics analysis of the differentially expressed proteins was performed using Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein–protein interaction (PPI) networks.

Results: H&E and Masson staining showed an artery-like structure of the SDAVF-DV. Immunostaining showed that vWF+ cells were not continuous in the SDAVF-DV. Although α-SMA+ and AT1+ cells were more abundant in the STV than in the SDAVF-DV, piezo-1 expression was lower in the SDAVF-DV. The SDAVF-DV showed different distributions of elastin, COL I, and COL III. COL IV and COL VI were decreased in the SDAVF-DV, while CD45+ cells and COX-1 were increased compared with those in the controls. No differences in CD68 expression and COX-2 staining were observed between the SDAVF-DV and controls. Compared with the STA, 95 proteins were upregulated and 303 proteins were downregulated in the SDAVF-DV. The most differential GO terms in each category were the adenylate cyclase-modulating G protein-coupled receptor signaling pathway, U6 snRNP, and SH3 domain binding. The most differentially expressed KEGG protein pathway was focal adhesion. Compared with the STV, the SDAVF-DV had 158 upregulated proteins and 362 downregulated proteins. The most differential GO terms in each category were lamellipodium assembly, U6 snRNP, and SH3 domain binding; and the most differentially expressed KEGG protein pathway was dilated cardiomyopathy. PPI analysis revealed PPIs among the top 300 proteins.

Conclusions: The SDAVF-DV exhibits specific pathology and protein expression changes under sustained high vascular pressure. The results of the present study provide insights into the pathogenesis of SDAVF formation at the protein level as well as a scientific foundation for further exploration of the pathophysiological mechanism of the SDAVF.

Extraspinal Vascular Malformation with Retrograde Drainage through a Radicular Vein: Treatment with Percutaneous Transgluteal Embolization

BACKGROUND

Spinal arteriovenous fistulas have abnormal connections between spinal arteries and veins. Early diagnosis and management are essential for preventing permanent neurologic deficits. Although symptoms of myelopathy are commonly related to established types of spinal arteriovenous fistulas within the spine, extraspinal arteriovenous anomalies may also result in similar pathology and pose challenges to conventional endovascular treatment.

CASE DESCRIPTION

A 61-year-old man presented with progressive weakness and decreasing sensation in the lower extremities. He had a remote history of craniopharyngioma surgery and deep venous thrombosis. Examination showed decreased strength and reflexes in the lower extremities. Magnetic resonance imaging demonstrated T2 cord signal changes and flow voids within the spinal canal. Angiogram showed bilateral internal iliac artery arteriovenous malformations with retrograde flow into a radicular vein and venous congestion of the medullary veins. Percutaneous transgluteal puncture of the superior gluteal vein was performed, and the abnormal inflow to the radicular vein was obliterated with coiling and Onyx embolization. The patient had significant clinical improvement, and follow-up imaging demonstrated resolution of T2 cord signal changes and flow voids.

CONCLUSIONS

Extraspinal vascular malformations with vascular myelopathy are extremely rare. They include a broad spectrum of complex vascular disorders and often require alternate endovascular approaches.

The antireflux mechanism - Angiographic anatomy and clinical implications

BACKGROUND

Early anatomists suspected that the radiculomedullary veins draining the spinal cord had valves preventing their retrograde filling with anatomical casting material. Modern investigations have discarded the presence of true valves and introduced instead the notion of a pseudo-valvular configuration for which the term antireflux mechanism was coined in the 1970s. The angiographic anatomy of the antireflux mechanism has not been well documented so far.

METHODS

This article discusses anatomical and clinical features of the antireflux mechanism with a series of 12 angiographic observations documenting the antireflux mechanism under normal and pathological circumstances.

RESULTS

The antireflux mechanism divides radiculomedullary veins into intradural and extradural segments. While the structure of the antireflux mechanism is not yet fully clarified, it includes at least a tight narrowing of the radiculomedullary vein at its point of passage through the thecal sac, which is angiographically detectable and likely protects the intradural venous system from transient or persistent surges in venous pressure (e.g. sneezing, pregnancy). This tight narrowing of the antireflux mechanism likely also represents an obstacle to normal anterograde flow, potentially leading to venous stagnation and thrombosis.

CONCLUSIONS

The antireflux mechanism includes at least a tight narrowing of the radiculomedullary vein, which likely influences the development and clinical expression of low-flow spinal arteriovenous fistulas and might impact the spinal venous drainage even in the absence of arteriovenous shunts.

Venous structures can mimic masses in the foramen magnum

Benign enhancing lesions at the foramen magnum is a recently described entity and believed to represent a varix or ganglion. These lesions are typically described as being single, located posterior to the intradural vertebral artery, and not attached to the dura. These 2 cases demonstrate previously undescribed variations in appearance of these lesions including contacting the posterior inferior cerebellar artery and lateral epidural plexus/dura, segmental dilatations, transverse and linear configuration, and visualization on an unenhanced CT head. These lesions most likely reflect bridging veins and are structures that clinicians should be aware of to avoid unnecessary follow-up or surgical intervention.

Primary conus medullaris arteriovenous shunt and secondary lumbo-sacral epidural arteriovenous fistula: One malformation can hide another

We report an anatomical-based association between conus medullaris pial arteriovenous shunt that drain caudally towards the lumbosacral area with very delayed onset of an acquired lumbar epidural shunt, draining secondarily towards intradural veins and responsible for a venous congestive myelopathy with identical clinical symptoms. These patients require close clinical and imaging follow-ups in order to propose adequate treatments before onset of irreversible neurological deficits. MRA should include the lumbo-sacral area in its field of view.

The clinical value of venous drainage in patients with spinal dural arteriovenous fistula

BACKGROUND

Spinal dural arteriovenous fistulas (sdAVF) with rapid deterioration are a known clinical phenomenon but have been rarely reported in the past. Clinical and radiologic features of these fistulas are analyzed for this study.

MATERIAL AND METHODS

We retrospectively reviewed our medical records for sdAVF patients who were treated in our center between 2006 and 2017. Our cohort was dichotomized in two groups; a) patients with acute/ subacute onset and rapid deterioration within a period of ≤6 months, b) patients with chronic progressive deterioration within a period of >6 months. MR findings at time of diagnosis were re-evaluated. All patients were treated microsurgically. Follow-up data were included.

RESULTS

Data of forty patients were available for this study. Rapid deterioration was observed in 13/40 (32.5%) patients. AL-score at time of diagnosis did not differ between both groups (3.2 ± 1.2 vs 3 ± 2, p = .78). Patients with rapid deterioration showed significantly more prominent arterialized perimedullay veins at time of diagnosis (p < .05). At the last follow-up (53 ± 3 months), patients with rapid deterioration improved up to one point on AL-scores (from 3.2 ± 1.4 to 2 ± 1.6) and those with chronic progressive deterioration were unchanged (from 3 ± 1.6 to 3 ± 1.7).

CONCLUSION

Patients with rapid deterioration in our group (32.5%) presented with a significantly more prominent appearance of the arterialized perimeduallry veins. This may reflect, in the earlier phase of the disease, a better compensation of the venous hypertension as well as the associated venous outlet disorder of the spinal cord. This may also explain the better outcome of these patients.

Spinal Epidural Arteriovenous Fistula with Perimedullary Venous Reflux: Clinical and Neuroradiologic Features of an Underestimated Vascular Disorder

BACKGROUND AND PURPOSE

The purpose of this study was to discuss the clinical and radiologic characteristics of spinal epidural arteriovenous fistulas (SEAVF) and demonstrate their specific angiomorphology in a single-center series.

MATERIALS AND METHODS

Thirteen consecutive patients were diagnosed with SEAVF at RWTH Aachen University Hospital between 2006 and 2018 and were included in this study. All patients had MR imaging and DSA before treatment; 10 of these 13 patients received contrast-enhanced MRA (CE-MRA).

RESULTS

The mean patient age was 72 ± 8 years. Paraparesis was present in 12 (92%) patients. Sphincter dysfunction and sensory symptoms were observed in 7 (54%) and 6 (46%) patients, respectively. The mean duration of symptoms was 6 ± 8 months. Congestive myelopathy on MR imaging was present in all patients. Prominent arterialized perimedullary veins were demonstrated in only 3 cases. CE-MRA revealed arterialized perimedullary veins and an arterialized epidural pouch in 9/10 (90%) patients, mostly located ventrolaterally. DSA demonstrated a multisegmental extension of the arterialized ventrolateral epidural pouch in 6 (46%) cases. An intradural radicular drainage vein was localized distant from the original fistula point in 3 (23%) patients.

CONCLUSIONS

Congestive myelopathy with an acute/subacute clinical course was the dominant finding in spinal epidural arteriovenous fistulas. CE-MRA is a powerful diagnostic tool for identifying arterialized perimedullary veins as well as an arterialized epidural pouch. While arterialized perimedullary veins frequently present with only mild enlargement and elongation in spinal epidural arteriovenous fistulas, the arterialized epidural pouch is frequently located ventrolaterally and may extend over several vertebral levels. DSA remains the criterion standard to precisely visualize a spinal epidural arteriovenous fistula and its intradural radicular drainage vein, which may be located distant from the fistulous point.

Concomitant conus medullaris arteriovenous shunts and sacral dural arteriovenous fistulas: pathophysiological links related to the venous drainage of the lesions in a series of five cases

Background

Spinal cord arteriovenous shunts (scAVSs) are a group of lesions located in the spinal cord itself or in the surrounding structures. The most common scAVSs are spinal dural arteriovenous fistulas (sDAVFs), which are acquired lesions. The pathogenesis of sDAVFs involves thrombosis and venous hypertension as trigger factors. Intradural scAVSs such as spinal cord arteriovenous nidus type malformations (AVMs) and pial arteriovenous fistulas are less common than sDAVFs and are considered to have a so-called ‘congenital’ origin. The association between different concomitant scAVSs is very rare and the association of sDAVFs with intradural scAVSs has been described in only a few case reports.

Methods

We describe a case series of five patients presenting with a conus medullaris AVS associated with a lower lumbar or sacral DAVF.

Results

Three of our patients were <30 years old at presentation. In four of these five cases the intradural scAVS drained caudally, engorging the epidural plexus in the same location as the sDAVF. In only one case, who presented with thrombosis of the drainage of the main compartment of a conus medullaris pial AVF, was the location of the DAVF opposite to the location of the residual drainage.

Conclusion

We discuss the pathophysiological link between scAVS and sDAVF on the basis of the rarity of the DAVF, the uncommon association between scAVS and sDAVF, the presence of sDAVF in young patients, and the venous hypertension created by the venous drainage towards the sacral area responsible for angiogenesis creating the dural shunt.

Clinical and Radiologic Characteristics of Deep Lumbosacral Dural Arteriovenous Fistulas

BACKGROUND AND PURPOSE

Spinal dural arteriovenous fistulas located in the deep lumbosacral region are rare and the most difficult to diagnose among spinal dural arteriovenous fistulas located elsewhere in the spinal dura. Specific clinical and radiologic features of these fistulas are still inadequately reported and are the subject of this study.

MATERIALS AND METHODS

We retrospectively evaluated all data of patients with spinal dural arteriovenous fistulas treated and/or diagnosed in our institution between 1990 and 2017. Twenty patients with deep lumbosacral spinal dural arteriovenous fistulas were included in this study.

RESULTS

The most common neurologic findings at the time of admission were paraparesis (85%), sphincter dysfunction (70%), and sensory disturbances (20%). Medullary T2 hyperintensity and contrast enhancement were present in most cases. The filum vein and/or lumbar veins were dilated in 19/20 (95%) patients. Time-resolved contrast-enhanced dynamic MRA indicated a spinal dural arteriovenous fistula at or below the L5 vertebral level in 7/8 (88%) patients who received time-resolved contrast-enhanced dynamic MRA before DSA. A bilateral arterial supply of the fistula was detected via DSA in 5 (25%) patients.

CONCLUSIONS

Clinical symptoms caused by deep lumbosacral spinal dural arteriovenous fistulas are comparable with those of spinal dural arteriovenous fistulas at other locations. Medullary congestion in association with an enlargement of the filum vein or other lumbar radicular veins is a characteristic finding in these patients. Spinal time-resolved contrast-enhanced dynamic MRA facilitates the detection of the drainage vein and helps to localize deep lumbosacral-located fistulas with a high sensitivity before DSA. Definite detection of these fistulas remains challenging and requires sufficient visualization of the fistula-supplying arteries and draining veins by conventional spinal angiography.

Arterial Hypertension Is Associated with Symptomatic Spinal Dural Arteriovenous Fistulas

OBJECTIVE

To determine possible systemic factors that may induce or be associated with the pathogenesis and pathologic course of spinal dural arteriovenous fistulas (SDAVFs), the most common type of arteriovenous disorder of the spinal cord and its meninges.

METHODS

We assessed the role of possible systemic (vascular) risk factors (arterial hypertension, diabetes mellitus, fat metabolism disorders, and nicotine dependence) by comparing the prevalence of these risk factors in an SDAVF cohort of 59 patients with the prevalence in the general population.

RESULTS

Age-corrected prevalence of arterial hypertension in the SDAVF cohort was significantly higher than in the general population (P < 0.001). Prevalence of diabetes mellitus (P = 0.150.), nicotine dependence (P = 0.561), adiposity (P = 0.217), and fat metabolism disorders (P = 0.125) did not differ from prevalence of comparable cohorts in the general population.

CONCLUSIONS

Our results and data from the literature suggest that arterial hypertension may play an important role in the development of SDAVF-related symptoms or the development of SDAVFs in the presence of other predisposing factors.

Endovascular treatment of spinal arteriovenous malformations

Spinal arteriovenous malformations (AVMs) are a rare but treatable cause of myelopathy and spinal cord hemorrhage. The clinical presentation and ideal treatment of these lesions vary widely, primarily due to differences in anatomic and angioarchitectural features. Six well-defined types of fistula have been defined: (1) intradural dorsal AVM; (2) intramedullary AVM; (3) extradural-intradural AVM; (4) intradural ventral AVF; (5) extradural/epidural AVF; and (6) conus medullaris AVM. Each of these lesions have unique clinical presentations and variable natural histories and endovascular treatment options. The principles of endovascular treatment include: (1) a complete understanding of the angioarchitecture and anatomic features of the lesion, including identification of radiculomedullary arteries; (2) careful spinal angiography; (3) identification of treatment goals prior to the procedure (i.e., complete occlusion versus partial occlusion aimed at altering natural history); (4) selection of proper embolic agent; and (5) careful follow-up in both the immediate postoperative setting and long term.