Aneurysm of Distal Medial Lenticulostriate Artery: Report of 2 Cases.

Background: Aneurysms originating from the distal portion of the lenticulostriate artery (LSA) are uncommon. Distal medial LSA (MLSA) aneurysms are particularly uncommon when compared with distal lateral LSA aneurysms, and their clinical features are unclear. Here, we present 2 patients with aneurysms of the distal MLSA who exhibited hemorrhages of the caudate nucleus and intraventricular region (intraventricular hemorrhage [IVH]).
Case Description: Patient 1 is a 50-year-old woman who was admitted to our hospital because of a hemorrhage in the left caudate nucleus and ventricles. She underwent external ventricular drainage (EVD). Cerebral angiography (CAG) performed on hospital day 24 showed an aneurysm located in the distal portion of the MLSA; however, CAG performed on admission revealed no abnormal vessels. We excised the aneurysm using a transcallosal-transventricular approach. Patient 2 is an 88-year-old woman who was admitted to our hospital with a right caudate nucleus hematoma and a dense IVH. She underwent emergent EVD. CAG demonstrated a 2.5-mm aneurysm in the distal MLSA, and a 6-mm aneurysm which originated from the right horizontal portion of the anterior cerebral artery (A1)-MLSA bifurcation aneurysm. We performed direct clipping of the A1-MLSA bifurcation aneurysm with proximal ligation of the distal MLSA aneurysm.
Conclusions: We should consider the possibility of a ruptured distal MLSA aneurysm when diagnosing a patient with IVH-with or without a caudate nucleus hematoma. Repeated imaging evaluations may be necessary to find the lesion.
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