Rapid Change in Shape of Unruptured Intracranial Aneurysm with Acute Perforating Infarction.

Acute ischemic stroke is a rare complication resulting from an unruptured intracranial aneurysm (UIA). Ischemic stroke adjacent to the aneurysms is considered the risk of rupture of aneurysms. However, there is presently no consensus on the optimal strategy for the management of UIAs with ischemic stroke. A 27-year-old woman presented with sudden onset left hemiparesis. Acute infarction of the right basal ganglia and an aneurysm of the right middle cerebral artery were discovered on brain imaging. Antiplatelet therapy was used to treat her. The diagnosis revealed ischemic stroke caused by a thrombosed aneurysm due to the change in the shape of the aneurysm on day 4. The UIA clipping procedure was performed on day 21 due to the risk of subarachnoid hemorrhage (SAH). The findings of the surgery and indocyanine green imaging revealed a partially thrombosed aneurysm and occlusion of a perforating artery. As is well known, enlargement of aneurysm size indicates increasing rupture risk. In the present case, after ischemic events developed, magnetic resonance angiography revealed enlargement of the aneurysm. The findings of the surgery revealed possible pathogenic mechanisms were perforating artery occlusion due to local extension of the luminal thrombus. Clinicians should be aware of the risk of ischemic stroke due to luminal thrombosis of the UIA and SAH and should consider urgent treatment of the UIA even immediately after ischemic stroke.