Delayed parenchymal hemorrhage following successful embolization of brainstem arteriovenous malformation. Case report.

A 64-year-old man presented with subarachnoid hemorrhage from a small brainstem arteriovenous malformation (AVM). Cerebral angiography showed a small AVM in the lateral midbrain, which was fed by a basilar perforating artery, and drained into the right transverse pontine vein and superior petrous vein. Endovascular embolization in the acute stage was selected to occlude the arteriovenous shunt and provide additional intensive treatment for cerebral spasm with lower risk of rebleeding. The AVM was occluded by embolization using n-butyl cyanoacrylate. Intraparenchymal hemorrhage in the ipsilateral pons was detected 1 month after treatment. The causes of the hemorrhage remain unclear.