Nontraumatic and noninfectious pseudoaneurysms on the circle of Willis: 2 case reports and review of the literature

Background: Nontraumatic and noninfectious pseudoaneurysms with similar shape of true saccular aneurysm on the circle of Willis are rare. Case Descriptions: Two patients with such pseudoaneurysms are reported, one is a 37-year-old man, the other is a 50-year-old woman. They presented with sudden headache; CT scan showed subarachnoid hemorrhage in both. Thorough medical history had been reviewed; physical and laboratory examination had been made but demonstrated no evidence of craniocerebral injury and intracranial or systematic infection. On the cerebroangiogram, they represented the same imageologic changes of true saccular aneurysm, but subsequent operation and pathologic examination revealed that they were pseudoaneurysms consisting of blood clot enclosed with a layer of connective tissue; degenerative changes may have contributed to their formation. Conclusion: Careful attention should be given in classifying these saccular pseudoancurysm from true saccular aneurysms because of their friable nature, tendency of rupture, and different pathologic findings. (C) 2008 Elsevier Inc. All rights reserved.