Self-thrombosing anterior cerebral artery aneurysm leading to a caudate infarct

Self-thrombosing intracranial aneurysms are relatively uncommon and the conditions that lead to their formation are unknown, although they can be seen following subarachnoid hemorrhage and in autopsy specimens. We seek to raise awareness of the unintended iatrogenic thrombosis of intracranial aneurysms, its ischemic consequences, and the use of mechanical thrombectomy in its treatment. A 50-year-old hypertensive woman presented with a sudden onset of severe headache concerning for a ruptured cerebral aneurysm (Hunt-Hess 2). HCT showed diffuse subarachnoid hemorrhage (modified Fisher grade 3), and CTA showed two aneurysms arising from an anterior communicating (ACOM) complex fenestration and one aneurysm arising from the proximal left anterior cerebral artery (ACA) A1 segment. Successful coil embolization of the distal ACOM aneurysm was followed by an attempted balloon-assisted coil embolization of a left ACA A1 aneurysm that led to self-thrombosis and partial occlusion of the A1 segment. After mechanical thrombectomy, there was significant reduction in left A1 thrombus burden. The patient developed an asymptomatic small infarct of the left caudate, likely by occlusion of an anatomic variant of the recurrent artery of Heubner arising from the A1 segment. To our knowledge, this is the first reported case of a self-thrombosing aneurysm during attempted balloon-assisted embolization. Propagation of the thrombus can lead to parent vessel occlusion and ischemia, and, in this case, an anatomic variant of the recurrent artery of Heubner from A1 made this more likely. Intra-arterial mechanical thrombectomy may be used in the treatment of an iatrogenic vessel thrombosis. Keywords: Self-thrombosing, Heubner artery, Aneurysm, Caudate, Anatomic variant