De novo aneurysm formation and regression after brain arteriovenous malformation embolization: case report

The formation of de novo aneurysms is a known complication of vessel occlusion (Wright RL, Sweet WH. Carotid or vertebral occlusion in the treatment of intracranial aneurysms: value of early and late readings of carotid and retinal pressures. Clin Neurosurg 1962:9;163-192). Aneurysms most commonly develop on newly formed primary collateral routes as a result of increased flow through these collaterals. Development of aneurysms is not commonly seen in vessels whose flow has been directly decreased by therapeutic or natural occlusion.

A 53-year-old woman with an intracerebral hemorrhage underwent cerebral angiography which demonstrated a right parietal AVM. An enlarged right ACA gave rise to 3 direct feeding pedicles. Leptomeningeal collaterals from the right MCA as well as the right PCA also gave collateral supply to the AVM. The lesion had superficial drainage into the superior sagittal sinus and deep venous drainage into the right posterior pericallosal vein. No feeding artery aneurysms or intranidal aneurysms were present. Treatment plan included preoperative embolization followed by surgical resection.

To our knowledge, this is the first reported case of a de novo aneurysm forming and regressing in an artery hemodynamically related to an embolized AVM. The short timescale of its development (6 weeks) is also noteworthy. The spontaneous regression suggests that at least some aneurysms forming in vessels after abrupt decrease in distal runoff may have a self-limited course. Such lesions may do best if not subjected to direct endovascular or surgical treatment.