Vascular Tumors and Malformations
Vascular Malformations
Most probably congenital, though may enlarge progressively. Some arteriovenous fistulas acquired, follow trauma or arterial or venous occlusion.
Arteriovenous Malformations (AVMs)
Affect brain more than dura, sometimes both.
Incidence approximately 1.5/100,000 population, half diagnosed at time of hemorrhage.
Pathology: tangle of abnormal arteries and veins with interposed sinuses lacking media; no capillaries. Variable location, blood supply.
Major risk is hemorrhage: parenchymal, intraventricular, or subarachnoid. Bleeding risk similar to aneurysms, but morbidity less. Features associated with increased bleeding risk: deep location, presence of deep-venous drainage, associated aneurysm, multiple arterial feeding vessels, small size. Most common in middle life. Less commonly, may cause chronic seizure disorder or headaches.
MRI, magnetic resonance angiogram (MRA) document AVM, prior major hemorrhage, intranidal aneurysms, main source of blood supply. Treatment plan requires conventional angiography.
Treatment: (a) surgical resection (most effective); usually preceded by embolization using glues, coils, other agents to reduce size and pressure within AVM. (b) Focused-beam radiotherapy (radiosurgery) for small (<2.5 cm), deep lesions not suitable for embolization or surgery.
Vein of Galen malformation: special AVM associated with deep venous system, often with marked aneurysmal dilation of vein of Galen. Complex blood supply, including arteries. Symptoms develop in neonatal period or early childhood; severe arterial shunting causes cardiac failure, midbrain compression with subsequent hydrocephalus. Treatment: embolization, occasionally followed by surgery.Related posts:
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