Idiopathic Lenticulostriate Artery Pseudoaneurysm Protruding into the Lateral Ventricle: A Case Report

We report a rare case of an idiopathic pseudoaneurysm causing intra-ventricular hemorrhage (IVH). A 28-year-old man presented with sudden onset of severe headache. He underwent external ventricular drainage for an isolated IVH in the right lateral ventricle. Digital subtraction angiog-raphy (DSA) revealed that the aneurysm (7.5×4.5 mm) arose from the distal part of the medial lenticulostriate artery. Following removal of the external ventricular drainage catheter, the aneurysm decreased in size (4.0×2.3 mm). However, follow-up DSA revealed a slightly enlarged aneur-ysm (4.2×3.2 mm) with morphologic change. The aneurysm was clipped via the interhemispheric transcallosal approach, but postoperative DSA re-vealed a residual aneurysm sac beside the clips. Given the risk of re-bleeding, a second operation was planned for complete resection of the aneurysm. After revised craniotomy and careful dissection of the caudate nucleus, the aneurysm sac was completely resected. Histopathological ex-amination revealed that the aneurysm was a pseudoaneurysm. The pa-tient recovered without any neurological sequel and was discharged. To the best of our knowledge, this is the first reported case of an idio-pathic lenticulostriate artery pseudoaneurysm protruding into the right lat-eral ventricle and causing an IVH that was successfully treated with mi-crosurgical resection. J Cerebrovasc Endovasc Neurosurg