Small unruptured partially thrombosed aneurysms and stroke: report of three cases and review of the literature.

Several case reports and studies suggest that partially thrombosed large and giant aneurysms are potential sources of distal embolic events. However, there are limited data on small thrombosed aneurysms as a possible cause of ischemic events. Three patients are reported who presented with acute ischemic stroke and in whom the initial imaging studies showed a small (<10 mm), unruptured, partially thrombosed aneurysm. In each case, the aneurysm location was confirmed by a conventional angiogram. In all cases, the aneurysms were found on the proximal middle cerebral artery, in the territory corresponding to the clinical symptoms of the stroke. The mechanism of middle cerebral artery embolic event was thought to be related to the thrombus within the aneurysm, causing subsequent embolization into distal related vascular territory. Two of these patients had craniotomy for aneurysm clipping; one was managed conservatively with medical therapy alone. Thrombosis of small, unruptured intracranial aneurysms should be considered as a possible cause of acute-onset stroke symptoms in patients with acute ischemic stroke. It is under-recognized in the current literature, and no guidelines currently exist for medical or surgical treatment of such aneurysms. Medical management is often decided on an individual basis. Surgical treatment mostly involves aneurysmal clipping rather than coiling.