Completely Thrombosed Aneurysms of the Posterior Cerebral Artery: A Comprehensive Review

Abstract

Background Completely thrombosed aneurysms of the posterior cerebral artery (CTPCAAs) are rare lesions with different characteristics and clinical behavior when compared with other intracranial aneurysms. Objective To describe and analyze the main features of CTPCAAs. Material and Methods Fifteen CTPCAAs were studied (14 literature cases plus one illustrative case). Clinical, radiologic, pathologic, and therapeutic data were obtained and analyzed. Results CTPCAAs are large (mean: 2.43 cm), located proximally (80% at P1–P2 segments), and show a slight predominance of a fusiform appearance. Posterior cerebral artery (PCA) occlusion ensued after aneurysm complete thrombosis in 73% of patients (11/15). However, only 33% of patients developed a PCA territory stroke, due to a rich distal arterial collateral network. Three mutually exclusive clinical presentations were observed: subarachnoid hemorrhage (SAH) (n = 3), “stroke-like” syndrome (n = 7), and “tumor-like” syndrome (n = 4). One case was incidental. Three treatments were performed: conservative (n = 7), endovascular (n = 1), and surgery (n = 7). CTPCAA exclusion was the goal of surgery. Neural structures decompression was also sought in tumor-like cases. CTPCAA elimination as a potential bleeding source was the target in stroke-like cases. General outcome among CTPCAAs was good (73% of cases scored Glasgow Outcome Scale 4–5/Modified Rankin Scale 0–2). Conclusions CTPCAAs are characterized by young age at presentation, male predominance, proximal location on PCA, and tendency to cause PCA occlusion. The PCAA clinical presentation depends on the mechanism of complete thrombosis. SAH and stroke-like syndrome CTPCAAs harbor a less organized thrombus than tumor-like CTPCAAs, which makes the aneurysm more prone to hemorrhagic/ischemic complications. Thus clinical presentation may indicate the clinical evolution in CTPCAAs. The management of CTPCAAs varied according to the patient's clinical condition and the risk evaluation for future complications derived from the aneurysm. Clinical surveillance and surgical removal were the most frequent treatment options performed. Surgery was focused on neural decompression and/or CTPCAA elimination as a potential source of bleeding.