Early spontaneous regression of multiple flow-related aneurysms following arteriovenous malformation nidal resection – A case report

Background: Treatment of intracranial flow-related aneurysms associated with arteriovenous malformation (AVM) represents a clinical conundrum. An understanding of the behavior of these flow-related aneurysms following surgical and endovascular treatment of AVM nidus could provide valuable insight into treatment options and better decision-making in acute presentation. We present a case of early regression of flow-related aneurysms following AVM nidal resection. Case Description: A 63-year-old man with known cerebellar vermian AVM and previously treated flow-related aneurysm presented with acute subarachnoid hemorrhage. He underwent digital subtraction angiography which demonstrated the known AVM in addition to multiple de novo flow-related aneurysms arising from the superior cerebellar artery and the posterior inferior cerebellar artery. The treatment plan was for surgical clipping of the culprit aneurysm and resection of the AVM in the same sitting. Only the AVM nidal resection was achieved at surgery with subsequent radiological disappearance of the associated flow aneurysms within a 7-day period. Conclusion: To the best of our knowledge, this is the third case of flow-related aneurysms achieving any degree of regression within hours to days following AVM nidal treatment. The distal location of the flow-related aneurysms and the availability of early postoperative imaging may have contributed to the detection of this rapid regression. This single case does not constitute enough evidence but adds to the conversation of whether options for treatment of flow-related aneurysms could include indirect treatment of the aneurysms through AVM surgical resection or endovascular nidal embolization.