OBJECTIVE: A ruptured aneurysm rarely causes a primary intraventricular hemorrhage. Cases of aneurysms concomitant with internal carotid artery occlusion are occasionally reported
however, no previous studies have described lateral posterior choroidal artery (LPChA)-associated aneurysms with internal carotid artery occlusion. CASE PRESENTATION: We experienced a case of intraventricular hemorrhage caused by the rupture of an LPChA aneurysm associated with the collateral circulation of internal carotid artery occlusion. After a detailed preoperative imaging study, the embolization was successfully achieved using n-butyl-2-cyanoacrylate without new neurological deficits. CONCLUSION: This case highlights the importance of knowledge of the functional anatomy of collateral anastomosis of the intraventricular choroidal arteries, which allowed safe and successful embolization of the aneurysm.