Long term follow-up of endovascular management of spinal cord arteriovenous malformations with emphasis on particle embolization

Pediatric Spinal Vascular Abnormalities: Overview, Diagnosis, and Management

Hemangioblastomas are true benign vascular neoplasms arising from pluripotent mesenchymal stem cells that give rise to vascular endothelial cells and are most commonly found in the cerebellum, spinal cord, brainstem, and retina. These tumors may be isolated sporadic lesions or may be associated with hereditary genetic factors in the case of von Hippel-Lindau (VHL) syndrome. Spinal cord haemangioblastomas constitute 1.1% to 2.4% of all central nervous system tumors105, with the majority being single tumors that present in the fourth decade of life 106. In the pediatric population, sporadic spinal cord hemangioblastomas are exceedingly rare. The prevalence of spinal cord hemangioblastomas in children is increased among those with VHL syndrome. The thoracic cord is the most common site for spinal cord hemangioblastomas, followed by the cervical cord. Although these tumors are benign, they cause disabling symptoms due to spinal cord compression, syringomyelia, or hemorrhage from the tumor itself or from aneurysms that form on tumor-feeding arteries or intra-tumoral vessels.

Endovascular approach to posterior spinal cord AV shunts via the anterior spinal artery

Intradural spinal cord arteriovenous shunts are challenging vascular lesions with poor prognosis if left untreated. Therapeutic options include endovascular treatment, microsurgery or a combined approach. Surgical approaches are more complex if the lesions are located anteriorly and supplied by the anterior spinal artery (ASA). ASA can also vascularize shunts located on the posterior surface of the spinal cord either by transmedullary arteries, pial circumferential arteries or, if affecting the lower portions of the cord, by the anastomotic channels of the basket. Each of these vessels can be used for endovascular navigation to reach the shunts with good results if appropriate anatomical rules are followed. We describe here some technical considerations based on the anatomical analysis for the embolization of posterior spinal cord arteriovenous shunts vascularized by the anterior spinal artery.

Angiographic Index for the Treatment Efficacy and Functional Outcomes of Spinal Cord Arteriovenous Shunts: the Vertebral Blush Sign

BACKGROUND

The functional outcomes in spinal cord arteriovenous shunts (SCAVSs) are usually unpredictable from current assessments of treatment results. We aimed to investigate and propose a new index marker, the vertebral blush (VB) sign, for assessing the treatment efficacy of SCAVSs.

METHODS

This retrospective cohort study enrolled patients diagnosed with SCAVSs between June 2012 and May 2021. The VB sign was defined as the angiographic finding of reappearance or enhanced contrast staining of the vertebral bodies fed by shunt-related arteries observed after shunt occlusion. The primary outcome was the improvement in motor/sensory disturbances or sphincter impairments within 1 year after treatment. The secondary outcome was shunt recanalization. VB sign characteristics and associations with outcomes were analyzed.

RESULTS

Of 65 patients with SCAVSs, 57 were eligible for VB sign assessment; among these, there were 26 with the VB sign and 31 without the VB sign. Among vascular shunts perimedullary arteriovenous fistula showed the greatest difference in prevalence rate between those with and without the VB sign (33.3%, n = 9/27 versus 10.0%, n = 3/30; P = 0.031). On multivariable logistic regression analysis, SCAVSs with the VB sign had significantly more favorable outcomes than those without the VB sign (adjusted odds ratio, 5.61; 95% confidence interval, 1.48-21.23; P = 0.01). There was no relationship between the VB sign and secondary outcomes (P = 0.35).

CONCLUSION

The VB sign is independently associated with functional recovery after shunt occlusion and could be an assessment tool for the treatment efficacy of SCAVSs.

Recurrence Rates Following Treatment of Spinal Vascular Malformations: A Systematic Review and Meta-Analysis

BACKGROUND

Spinal vascular malformations (SVMs), including arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs), are a varied group of vascular lesions that can be subclassified according to localization, vascular structure, and hemodynamics. Early intervention is necessary to halt progression of disease and minimize irreversible dysfunction. We sought to characterize initial treatment success and recurrence rates following interventional treatment of various types of SVMs.

METHODS

A systematic review and meta-analysis were performed following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. SVMs were categorized into 4 groups: dural AVFs, perimedullary AVFs, intramedullary AVMs, and extradural-intradural AVMs (e.g., epidural, paraspinal). Initial occlusion, recurrence, and complication rates were compared using random-effects analysis.

RESULTS

There were 112 manuscripts included, with a total of 5626 patients with SVM. For treatment, 2735 patients underwent endovascular embolization, 2854 underwent surgical resection, and 37 underwent stereotactic radiosurgery. The initial treatment success and overall recurrence rates following surgical resection of all SVMs were 89.5% (95% CI: 80.5%-98.5%) and 2.3% (95% CI: 0.9%-3.7%), respectively. Those rates following endovascular embolization were 55.9% (95% CI: 30.3%-81.5%) and 27.7% (95% CI: 11.2%-44.2%), respectively. Higher rates of initial treatment success and lower rates of recurrence with surgery were observed in all subtypes compared to embolization. Overall complication rates were higher after embolization for each of the SVM categories.

CONCLUSIONS

Surgical resection of SVMs provided higher rates of initial complete occlusion and lower rates of recurrence than endovascular techniques. Attaining technical success through obliteration must still be weighed against clinical impact and natural history of the specific vascular malformation.

Spinal vascular malformations: Angiographic evaluation and endovascular management

Spinal vascular malformations (SVM) are classified based on their location (intramedullary, perimedullary, radicular, extradural) and flow pattern (high-flow, low-flow, no arteriovenous shunt). High-flow SVMs are generally congenital lesions diagnosed in children and young patients without gender predominance. They present with hemodynamic disturbances, mass effect, or hemorrhages, but may also be discovered incidentally. Low-flow SVMs tend to be acquired lesions presenting in older men with progressive myelopathy caused by spinal venous hypertension. They are rarely associated with vascular syndromes but may accompany prothrombotic conditions. The sensitivity and specificity of conventional MRI are excellent for high-flow SVMs but poor for low-flow lesions, which are frequently diagnosed with extensive delays reducing the potential for favorable outcomes. The sensitivity of advanced MRI techniques remains unclear, notably for the detection of low-flow shunts without flow voids on conventional MRI. Catheter angiography remains the gold standard modality for the evaluation of the spinal vasculature and its disorders. SVMs can be treated by surgical or endovascular means. Initially plagued by high recurrence rates due to inadequate embolization material, endovascular techniques represent nowadays a valid alternative to surgery, thanks notably to the introduction of liquid embolic agents.

Introduction to Diagnostic and Therapeutic Spinal Angiography

This article describes the basic principles of diagnostic and therapeutic spinal angiography as practiced by the author, including catheterization and radioprotection techniques, the selection of endovascular devices and embolization agents, and procedural complications.