Cerebral arteriovenous malformation (AVM)

Created 23/04/2021, last revision 22/01/2023

  • brain AVMs represent congenital developmental defects (present in about 1.4-4% of the population); they probably expand over time ( AVMs are diagnosed at a mean age of 31 years)
  • AVM comprises abnormally enlarged feeding artery and draining veins, between which lies a conglomerate of A-V junctions closely associated with the brain parenchyma (nidus)
    • feeding arteries (one or more) are enlarged, tortuous; in 10-20% of cases, an aneurysm develops, which is often the source of bleeding / rebleeding
    • in the nidus, there are abnormal arteries and veins with no capillaries (arteries are directly connected to veins)
    •  the intranidal aneurysm is frequent (up to 50%)
    • draining veins (one or more) are tortuous, dilated, may cause mass effect, venous aneurysms (venous pouches) may be seen as well
    •  if the transition between the feeding artery and draining vein is made directly (without nidus), it is called an arteriovenous fistula (a different type of cerebral vascular pathology)!
  • localization of AVM
    • supratentorial: ~85%  (2/3 superficial, 1/3 deep)
    • infratentorial: ~15%
  • AVMs are solitary in most cases (multiple in < 5% of cases)
    • multiple AVMs are present in hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome) or Wyburn-Mason syndrome (craniofacial arteriovenous metameric syndrome)
  • AVMs are often discovered incidentally on CT/MRI examinations made for other reasons
  • parts of AVM have a histologically abnormal structure, gliosis or calcification are found around the lesion
  • clinical manifestation is usually between 20-40 years of age (as opposed to DAVF, which is between 40-70 years of age)
  • concerning treatment options, it is essential to determine
    • number of supplying vessels
    • size of the nest
    • type of drainage (superficial or deep venous system)


  • nidus composition
    • compact (or glomerular) nidus: abnormal vessels with no normal brain tissue interposed
    • diffuse (or proliferative) nidus: no well-formed nidus is present; brain tissue is interspersed amongst the anomalous vessels
  • The Spetzler-Martin arteriovenous malformation (AVM) grading system assigns points for various angiographic features to predict the morbidity/mortality risk of surgery
Spetzler-Martin AVM grading scale (grade I-V)
Nidus size – largest nidus diameter on angiography
  • small  (< 3 cm)
  • medium (3-6 cm)
  • large (> 6 cm)
The eloquence of the adjacent brain
  • non-eloquent
  • eloquent
    • sensory, motor, language, or visual cortex
    • internal capsule
    • hypothalamus / thalamus
    • cerebellar peduncles (superior, middle, or inferior) and cerebellar nuclei
    • brainstem

Venous drainage → anatomy of veins and sinuses

  • superficial veins
  • deep cerebral veins
Spetzler-Martin grade 3
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Clinical presentation

  • incidental finding in asymptomatic patients (about 15%)
  • intracerebral, intraventricular, and subarachnoid hemorrhage (40-65%)
    • risk of bleeding 1-4%/year, risk of rebleeding about 20% in the first year
    • risk factors:
      • previous bleeding
      • deep localization and drainage
      • concomitant aneurysm in the nidus or feeding arteries
    • the mortality rate for the first bleeding is about 10%, and about 20% for the third bleeding
  • epileptic seizures (20-25%)
  • headaches (15%)
  • focal neurological deficits
    • a consequence of bleeding, mass effect, or steal syndrome
  • pulsatile tinnitus (vascular murmur)

Diagnostic evaluation

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Differential diagnosis

  • other cerebral vascular malformations   Vascular malformations
    • cerebral proliferative angiopathy (CPA)   Cerebral proliferative angiopathy (CPA)   Proliferative angiopathy ("diffuse AVM")
      • absence of early, large venous drainage
      • involvement of an entire lobe or hemisphere as a diffuse network with normal neural tissue intermingled with the abnormal vessels
      • more common in females (2:1) and presents at a mean age of 20 years
      • the risk of neurological deficits after the surgical or endovascular treatment is high
    • craniofacial arteriovenous metameric syndrome (CAMS)
    • developmental venous anomaly (DVA)
    • dural arteriovenous fistula (DAVF)
  • malignant tumor


  • higher Spetzler-Martin grade ⇒ higher surgical risk   Risk of surgery and radiosurgery according to Spetzler-Martin grade
    • surgery is safe for grades 1 and 2 (good outcome in 95-100% of patients)
    • individual assessment is needed for grade 3
    • grades 4 and 5 are burdened with high perioperative risk due to potential damage to the draining venous system, which may serve the AVM and surrounding healthy tissue. The alternative here is conservative management (good outcome ~35%)
  • other factors increasing the risk of bleeding:
    • aneurysm in the feeding arteries or nidus
    • venous stasis

Conservative therapy

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Surgery/endovascular treatment

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Cerebral arteriovenous malformation (AVM)