Rare Subtype of Venous-Predominant Parenchymal Arteriovenous Malformation (AVM)

Abstract

An 18-year-old male, who had two previous attacks of subarachnoid hemorrhage, presented asymptomatic and neurologically intact, after complete recovery from hemorrhage-associated severe headache. He was treated with upfront (primary); Linac-based SRS for right, frontal, large, diffuse, rare subtype of venous-predominant, parenchymal AVM, mimicking atypical arterialized developmental venous anomaly (DVA). The target volume of 12.5 cc received a marginal dose of 25.0 Gy normalized to 80% isodose line. The maximum dose to optic chiasm was 15.8 Gy. At 3 months post-SRS, the patient experienced moderate headache and vomiting, which resolved gradually over couple months with steroid and diuretic medications. Serial post-SRS follow-up imaging showed progressive reduction in the size of AVM nidus till its non-visualization at 11 months post-SRS. The follow-up images also showed perinidal high signal in T2 and FLAIR studies, denoting vasogenic edema, and perinidal large heterogeneously enhancing lesion, in T1 Gadolinium-enhanced study, denoting radiation-induced parenchymal changes. At last radiological follow-up (55 months post-SRS), conventional cerebral angiography documented complete obliteration of AVM nidus. The radiosurgery treatment was successful, and the patient was neurologically intact throughout the entire follow-up period of 64 months post-SRS.