A Dissecting Aneurysm of the Distal Medial Lenticulostriate Artery: Case Report.

Background: Medial lenticulostriate artery (MLSA) aneurysms are rare; to our knowledge, only 2 cases without an association with moyamoya disease have been documented. We treated a ruptured dissecting aneurysm of the distal MLSA surgically using a tube retractor.

Case Description: A 66-year-old woman suffered a sudden-onset disturbance in consciousness. Computed tomography showed diffuse subarachnoid hemorrhage and a dense intraventricular hematoma associated with acute hydrocephalus. She underwent emergent ventricular drainage. Angiography revealed a 3-mm distal MLSA aneurysm. On repeat angiographs, the aneurysm had not disappeared. Because the stenotic, narrow structure of the proximal portion of the MLSA disallowed the endovascular approach, we performed direct surgery via the transventricular approach using a tube retractor. The aneurysm on the intraventricular surface of the anterior horn of the lateral ventricle adjacent to the caudate nucleus was exposed. We resected the aneurysm under transcranial motor-evoked potential monitoring because neck clipping would have endangered the patency of the MLSA. Her postoperative course was uneventful. The pathologic diagnosis was ruptured dissecting aneurysm.

Conclusions: There is no definitive strategy to treat distal MLSA aneurysms. Our experience illustrates that natural healing of the vessel wall cannot be expected in all cases. Therefore, less-invasive direct surgical as well as endovascular treatment should not be ruled out in patients with ruptured distal MLSA aneurysms.