Pial arteriovenous malformation with massive perinidal edema.

It is generally considered that perinidal edema in an arteriovenous malformation (AVM) is caused by a concomitant intracerebral hematoma. We report a rare case of AVM with perinidal massive edema which was possibly not due to hemorrhage, and discuss the pathophysiological mechanisms of such edema development. A 60-year-old woman presented with a sudden onset severe headache. Computed tomography (CT) scans obtained two hours after the onset showed an AVM-like lesion with a small hematoma in the right parieto-occipital lobe, and unexpectedly early development of massive edema adjacent to the hematoma. Angiograms demonstrated a medium-sized AVM, and severe stenosis in the draining vein which suggested the presence of venous hypertension at prestenotic sites. Repeated CT scans and magnetic resonance (MR) images in the chronic period after the hemorrhage demonstrated persistence of the perinidal edema with mass effect. Removal of the lesion was achieved 2 months after the onset. MR images 3 months after the operation showed marked reduction of perinidal edema. The time course of the perinidal edema suggests that its development was unrelated to the hemorrhage. The findings indicate that increased venous pressure secondary to severe stenosis of the draining vein may possibly contribute to the development of perinidal edema.