Spinal AVM¶

Definition¶

Spinal arteriovenous malformations (AVMs) are true vascular malformations with a nidus (tangle of abnormal vessels) within or on the surface of the spinal cord. They are classified as glomus (compact nidus, Type II) or juvenile (diffuse, Type III). Unlike dural AVFs, spinal AVMs typically present in younger patients and can cause hemorrhage, ischemia, or mass effect.

Types¶

Glomus AVM (Type II)¶

Compact intramedullary nidus, usually in the cervicothoracic cord
High-flow with enlarged feeding arteries and draining veins
Presents with hemorrhage (hematomyelia, subarachnoid hemorrhage) or progressive myelopathy

Juvenile AVM (Type III)¶

Large, diffuse, involving the cord, nerve roots, vertebral bodies, and paravertebral tissues
Rare and often inoperable
Presents in childhood/adolescence

Imaging Findings¶

MRI¶

Intramedullary flow voids — Tangle of vessels within the cord (the nidus)
Perimedullary flow voids — Enlarged draining veins on the cord surface
Cord hemorrhage — Hemosiderin staining (low T2), acute blood products
Cord edema — T2 hyperintensity from venous congestion or ischemia
Cord expansion — From the nidus itself and/or hemorrhage

Spinal Angiography¶

Defines the nidus, feeding arteries (anterior spinal artery, posterior spinal arteries), and draining veins
Essential for treatment planning
Identifies the artery of Adamkiewicz (must be preserved to avoid cord infarction)

Clinical Pearl

The critical difference between a spinal dural AVF and an intramedullary AVM: dural AVF shows flow voids on the cord surface with diffuse cord edema but no nidus; intramedullary AVM shows flow voids within the cord with a visible nidus, and may present with hemorrhage. Dural AVFs almost never hemorrhage; AVMs frequently do.

Key Points¶

True vascular malformation with an intramedullary nidus
Glomus (compact) and juvenile (diffuse) subtypes
Presents with hemorrhage or progressive myelopathy in young patients
Flow voids within the cord distinguish AVM from dural AVF
Spinal angiography is essential for treatment planning
Treatment options include embolization, surgery, or both

References¶

Kona MP, Buch K, Singh J, Rohatgi S. Spinal Vascular Shunts: A Patterned Approach. AJNR Am J Neuroradiol. 2021;42(12):2110-2118. https://pmc.ncbi.nlm.nih.gov/articles/PMC8805746/
McCarty J, Chung C, Samant R, et al. Vascular Pathologic Conditions in and around the Spinal Cord. RadioGraphics. 2024;44(9):e240055. https://pubmed.ncbi.nlm.nih.gov/39207926/
Spetzler RF, Detwiler PW, Riina HA, Porter RW. Modified classification of spinal cord vascular lesions. J Neurosurg. 2002;96(2 Suppl):145-156. https://pubmed.ncbi.nlm.nih.gov/12450276/
Abecassis IJ, Osbun JW, Kim LJ. Classification and pathophysiology of spinal vascular malformations. Handb Clin Neurol. 2017;143:135-143. https://pubmed.ncbi.nlm.nih.gov/28552135/
Takai K. Spinal Arteriovenous Shunts: Angioarchitecture and Historical Changes in Classification. Neurol Med Chir (Tokyo). 2017;57(7):356-365. https://pmc.ncbi.nlm.nih.gov/articles/PMC5566708/
Karsonovich T, Davidson CL, Sampath R. Arteriovenous Malformations of the Central Nervous System. In: StatPearls. Treasure Island (FL): StatPearls Publishing; updated 2024 Mar 4. https://www.ncbi.nlm.nih.gov/books/NBK531479/
Spinal arteriovenous malformations. Radiopaedia.org. https://radiopaedia.org/articles/spinal-arteriovenous-malformations