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“Getting Untangled”: A Review of Arteriovenous Malformations of the Spine 2011

General Spine

Sri Preethi, Vagvala, MD
Meeta, Gajjar, MD, Non ASSR Member
Gleb, Gorelick, MD, Non ASSR Member
Surya, Nadimpalli, MD, Non ASSR Member

Poster

Purpose

Arteriovenous malformations of the spine are rare but clinically important entities. They require an accurate diagnosis as they can cause severe neurologic deterioration, potentially reversible myelopathy and even death if not recognized and treated appropriately. This educational exhibit will illustrate the various types of spinal arteriovenous malformations with emphasis on imaging and appropriate approaches to treatment.

Methods & Materials

1. Become familiar with the normal spinal cord vascular anatomy. 2. Review the anatomic and typical imaging features ( CT, MR, and spinal angiography) of each of the four types of spinal arteriovenous malformations. 3. Recognize the differences in epidemiology and clinical presentations of each of the four types of spinal arteriovenous malformations. 4. Review the current treatment options and prognosis.

Results

Arteriovenous malformations of the spine can be classified into four types: dural or peridural arteriovenous fistulas (Type I), spinal cord vascular malformations (Types II and III) and spinal cord arteriovenous fistulas (Type IV). MR is the imaging modality of first choice in suspected spinal vascular malformation and should be complemented by selective spinal angiography for proper categorization. Dural AVF (Type I) occurs when a fistula develops between an arterial feeder to the venous circulation in the dural root sleeve. Dilated pial veins along the cord surface on MRI is a helpful distinguishing feature. Therapy is aimed at occluding the draining vein by embolization or surgical approach. Prognosis is good with early diagnosis and treatment, potentially preventing irreversible cord infarction. Glomus AVM (Type II) consists of an intramedullary nidus, with feeding vessels draining into the coronal venous plexus. Compact segment of serpentine intramedullary flow voids on MRI can be a discriminating feature. It clinically presents with progressive myelopathy, often with periods of acute neurologic impairment, secondary to hemorrhage. Treatment involves initial embolization to reduce arterial steal and improve cord perfusion. Subsequent surgical removal of residual nidus is generally considered as recanalization can occur over time. Juvenile AVM (Type III) are large, complex lesions, both intra and extramedullary in location with possible extraspinal extension, often arising from different cord levels. Given their size and vascular complexity, complete resection is generally not possible and prognosis is poor. Perimedulary AVF (Type IV) occurs when fistulous connection is intradural but peri or extramedullary in location. Displacement of the spinal cord on MRI is a helpful distinguishing feature. Three subcategories have been recognized with appropriate different treatment approaches for each lesion.

Conclusion

Knowledge and recognization of the clinical and imaging features of spinal arteriovenous malformations is important in proper timely diagnosis and determination of appropriate treatment methods.

References/Financial Disclosures

1. Morris P. Practical neuroangiography. Philadelphia: Lippincott Williams & Wilkins; 2007: 373-378. 2. Krauss WE. Vascular anatomy of the spinal cord. Neurosurg Clin N Am. Jan 1999;10(1):9-15. 3. Krings T, Lasjaunias PL, Hans FJ, Mull M, Nijenhuis RJ, Alvarez H, Backes WH, Reinges MH, Rodesch G, Gilsbach JM, Thron AK. Imaging in spinal vascular disease. Neuroimaging Clin N Am. 2007 Feb;17(1):57-72. Review. 4. Krings T, Geibprasert S. Spinal dural arteriovenous fistulas. AJNR AM J Neuroradiol. 2009 Apr;30(4):639-48. Epub 2009 Feb 12. 5. Barrow DL. Intracranial Vascular Malformations. Park Ridge, Ill: American Association of Neurological Surgeons; 1990.