arteriovenous malformation
Abnormal tangle of blood vessels with direct arterial-to-venous connections, bypassing normal capillary beds and carrying risk of hemorrhage.
Full Definition
An arteriovenous malformation (AVM) is a congenital vascular anomaly consisting of a nidus of abnormal vessels that directly connect arteries to veins without intervening capillaries. This abnormal anatomy creates high-flow, low-resistance shunting that can lead to hemorrhage, seizures, or progressive neurological deficits. Brain AVMs are classified by the Spetzler-Martin grading system, which considers size, eloquence of adjacent brain tissue, and venous drainage patterns. Imaging evaluation typically includes MRI, MRA, and often DSA to fully characterize the lesion anatomy and guide treatment planning, which may involve surgical resection, stereotactic radiosurgery, or endovascular embolization.
Usage
Usage note: Include Spetzler-Martin grade when characterizing AVMs for treatment planning.
In Context
- "MRI revealed a left parietal arteriovenous malformation with associated hemorrhage and surrounding edema." — Emergency imaging report
- "The Spetzler-Martin grade III AVM was deemed suitable for stereotactic radiosurgery treatment." — Multidisciplinary conference note