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Arteriovenous Malformation (AVM)

Last Updated: October 1, 2018

Open Table of Contents: Arteriovenous Malformation (AVM)

Figure 1: Noncontrast CT (top row) demonstrated a serpiginous region of masslike hyperdensity centered within the left precentral gyrus with adjacent hypodense gliosis. The corresponding MRI images demonstrates a tangle of serpiginous low signal flow voids on T2 (middle row left) with minimal associated anterior contrast enhancement (middle row right). AP (bottom row left) and left lateral (bottom row right) conventional angiographic images demonstrate a large tangle of vessels that has an arterial supply from multiple branches of the MCA and primarily drains into the superior sagittal sinus.


  • Pial vascular malformation of brain with arterial to venous shunting through a central nidus without an intervening capillary bed


  • Both sporadic and syndromic forms
  • Dysregulation of vascular endothelial growth factor (VEGF)
  • Often contains gliotic tissues, calcifications and blood in various stages

Clinical Features

  • Symptoms
    • Highly variable ranging from an incidental finding, seizure, headache, ischemia due to vascular steal, and hemorrhage
  • Age
    • Peak presentation 20-40 years
  • Gender
    • M=F
  • Grading
    • Spetzler-Martin Scale
      • Based on size, location and venous drainage pattern


  • General
    • “Bag of worms” on MR with minimal to no mass effect
    • 85% are supratentorial
  • CT
    • May be normal
    • Iso to slightly hyperdense vessels with avid enhancement
    • 25% will have calcifications
  • MR
    • T1
      • Dependent on flow rate, direction and presence of hemorrhage
    • T2
      • Tangle of serpiginous low signal flow voids
      • May have hemorrhage in different stages
    • GRE
      • Blooming if hemorrhage or calcifications
    • Contrast
      • Avid enhancement or flow voids of numerous tangled vessels and often large draining veins
  • Conventional Angiogram
    • Best delineates internal structure
    • Helpful for evaluating arterial supply and venous drainage
  • Imaging Recommendations
    • Conventional Angiogram
    • Protocol advice
      • MR with contrast and GRE sequences
  • Mimic
    • AVM’s can be difficult to distinguish from other vascular lesions or potentially an underlying neoplasm with extensive neovascularity. Typically, an AVM can be distinguished from an underlying neoplasm given the lack of mass effect or masslike enhancement.

For more information, please see the corresponding chapter in Radiopaedia, and the Arteriovenous Malformation chapter within the Cerebral Vascular Diseases sub-volume in the Neurosurgical Atlas.

Contributor: Sean Dodson, MD

DOI: https://doi.org/10.18791/nsatlas.v1.03.02.04


Ellis MJ, et al. Angioarchitectural features associated with hemorrhagic presentation in pediatric cerebral arteriovenous malformations. J NeuroIntervent Surg. 2013; 5:191-95.

Geibprasert S, et al. Radiologic Assessment of Brain Arteriovenous Malformations: What Clinicians Need to Know? Radiographics. 2010; 30:483-501.

Griffiths PD, et al. Brain Arteriovenous Malformations: Assessment with Dynamic MR Digital Subtraction Angiography. AJNR. 2000; 21:1892-99.

Moghrabi A, et al. Arteriovenous Malformation Mimicking Recurrent Medulloblastoma. Med and Ped Onc. 1994; 22:140-43.

Shankar JJS, et al. Angioarchitecture of Brain AVM Determines the Presentation with Seizures: Proposed Scoring System. AJNR. 2013; 34: 1028-1034.

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