Cerebrovascular anomalies

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Intracranial arteriovenous shunts

• Arteriovenous malformations (AVM)

• Vein of Galen malformation

• Arteriovenous fistula (AVF)

• Dural AVF

• Dural sinus malformations (DSMs)

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Arteriovenous malformation (AVM)

Definition: Congenital abnormality consisting of connections between arteries and veins without intervening capillary bed 

 

• AVM are most common cause of ICH in children (30-55%)

• High flow, pressure and shear stress lead to abnormalities of the involved vessels and increase the risk for hemorrhage

• Aneurysms can be seen in the nidus and/or feeding vessels

• Aneurysms present in 16% (children)

 

Clinical associations:

• Facial AVM or cerebrofacial metameric syndromes (Bonnet-Dechaume-Blan or Wyburn-Mason syndrome)

• Genetic syndromes: hemorrhagic hereditary telangiectasia (HHT), neurofibromatosis type I

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Presentation​

• 18% of symptomatic AVM present prior to 15 years of age

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• Neonatal presentation (rare)

  • Congestive heart failure (50%), hemorrhage (37.5%)

• Infant

  • Hemorrhage (30%, macrocrania (27%), heart failure (23%)

• Childhood

  • Hemorrhage (75%), seizures (15%)

• Other:

  • Focal ischemia (steal phenomenon)

  • Headache (non specific) - ? True true and unrelated

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• Cerebellar (15% of all AVMs) - more likely to present with hemorrhage

• Mortality from ruptured AVM 25 %

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Risk for Hemorrhage

• 2-4 % per year for unruptured AVM

• Increased risk for hemorrhage  once symptomatic

  • Risk greatest in the first year post hemorrhage (10-32%)

• High risk AVM features

  • Exclusively deep draining veins

  • Presence of associated nidal aneurysm (7 vs 4%)

  • Infratentorial or deep location

• Hemorrhage risk is not altered by partial obliteration

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Diagnostic Studies

• HCT

• CTA or MRA

• Conventional angiogram

  • At time of the bleed to determine if there is any imminent risk of rebleeding (e.g. aneurysm rupture or pseudo aneurysm).

  • Repeat 6-8 weeks later (wait for the hematoma to resolve) for embolization or surgical planning

  • Gold standard, CTA, MRI/MRA – provide fewer details on the architecture of the AVM

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Management

• Embolization

  • Can be done alone or prior to surgery or stereotactic radiation

  • Risk of embolization: hemorrhage, unintended vessel embolization, changes in perfusion pressure leading to edema and/or hemorrhage

• Surgery

• Radiosurgery

  • Focal high dose radiation sclerosis vessels with obliteration occurring over the following 1-2 years

  • AVM < 3.5 cm are best suited

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