Arteriovenous Malformation
Background
What is the avg age at presentation for arteriovenous malformations (AVMs)?
The avg age at presentation for AVMs is 30 yrs.
What is the nidus of an AVM?
The nidus is a tangle of abnl arteries/veins connected by at least 1 fistula.
What is the main histologic abnormality in the vasculature of an AVM?
Absence of smooth muscle layer; ↑ venous pressure (fibromuscular thickening with incomplete elastic lamina)
What is the morbidity and mortality per bleed for AVMs?
Morbidity: 30%–50%/bleed
Mortality: 5%–10%/bleed (1%/yr)
What is the rate of hemorrhage per yr for AVMs?
AVMs have a 2%–4% chance of hemorrhage/yr.
Are most AVM cases familial or sporadic?
Most AVMs are sporadic.
What familial/genetic syndromes are associated with AVMs?
Osler-Weber-Rendu and Sturge-Weber syndromes are associated with AVMs.
What characteristics portend an increased risk of hemorrhage from AVMs?
Previous hemorrhage, aneurysm, deep venous sinus drainage, deep location, single draining vein, and venous stenosis
Aneurysms are found in what % of pts with AVMs?
6%–8% of AVM pts harbor aneurysms.
Workup/Staging
What are common presenting signs of AVMs?
Intracerebral hemorrhage (42%–72%) > seizures and HA
What imaging modality is ideal to r/o a bleed?
CT is ideal to r/o cerebral bleeds.
What is the gold standard imaging modality for AVMs?
Angiography is the gold standard modality for imaging AVMs.
What other imaging modalities can be used for AVMs? What are their advantages?
CT angiography (good vascular detail), MR angiography (good anatomy detail), functional MRI (eloquent areas), and diffusion tensor imaging (for white matter tracts)
What scale is used to evaluate AVM pts for surgery?
Spetzler-Martin scale/grading system (totals possible: I–V)
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