A Ruptured Large Thrombosed True Posterior Communicating Artery Aneurysm Treated with Endovascular Treatment Three Times

Objective: We report a case of ruptured large thrombosed true posterior communicating artery (PCoA) aneurysm and consider its treatment. Case Presentation: A 71-year-old male patient had a left ruptured large thrombosed true PCoA aneurysm (maximum diameter 23 mm) with a small neck. Intra-aneurysmal coil embolization via the internal carotid artery was performed to preserve the premammillary artery (PMA). The adjunctive technique could not be used because the diameter of the PCoA was 1.5 mm. The result was a neck remnant and the aneurysm was recanalized. After 14 months, similar treatment was performed, and the aneurysm was recanalized again. The acute and twisted angle of the PCoA origin and the thinness of the PCoA were considered as factors for incomplete embolization. Because the distance between the origin of the PMA and aneurysmal neck was 5 mm, short-segment internal trapping of the aneurysm was performed 13 months after the second embolization. As a result, the PMA was no longer visualized on DSA; however, he had no neurologic deficit. The aneurysm remained obliterated after 7 months. Conclusion: Making a tight intra-aneurysmal coil embolization of a large thrombosed true PCoA aneurysm is difficult. If there is a certain distance between the PMA and the aneurysm neck, short-segment internal trapping might be useful to treat it.