Arteriovenous malformation
- 85% are suptratentorial
- High-flow with A-V shunting through a complex nidus of arterioles and venules without intervening capillary bed
- Dysregulated angiogenesis, usually sporadic but can be syndromic (increased incidence with age)
- Annaul bleeding risk is 2-4%
- Most common presentation is spontaneous hemorrhage, after that seizure, focal neuro def, or incidental
- Imaging features:
- CT - may see parenchymal hematoma or Ca
- Small unruptured AVMs usually not visible
- MRI
- T1 - bright hemorrhage
- T2 - prominent dark flow voids
- FLAIR - may see reactive gliosis in the area
- DSA is gold standard to visualize nidus, draining veins, and feeding arteries
- Grading:
- Spetzler-Martin scale predicts surgical morbidity (higher score = higher risk of open surgery)
- Size, <3cm (1 pt), 3-6 (2), >6 (3)
- Location - noneloquent (0) vs eloquent (1)
- Eloquent refers to brain areas that directly controls function (eg. motor cortex, somatosensory, visual cortex, auditory, Broca's, Wernicke's)
- Drainage - superficial (0) vs deep (1)
- Treatment:
- If ruptured then surgical decompression where the malformation may or may not be resected
- Microsurgical resection depending on S-M scale
- Endovascular embo
- Stereotactic
- May take years to see effect
- Limited to small AVMs