title: Pedunculated basilar terminus aneurysm with pseudo-septation due to anterior herniation through a perforated membrane of Liliequist.
abstract: Septations within cerebral arteries or aneurysms are exceedingly rare in the absence of associated fenestrations. We report an unusual unruptured pedunculated basilar apex aneurysm, with a "pseudoseptation" between the main aneurysmal sac and an anterior compartment, which was, in fact, represented by a perforation in the membrane of Liliequist, permitting anterior aneurysmal herniation into the carotid-chiasmatic cistern. The patient was successfully treated with detachable coils. This case is unusual on 2 accounts: 1) the aneurysm's appearance, and 2) the presence of a large fenestration in the membrane of Liliequist, of which anatomic features are herein reviewed.
authors.affiliation: Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA. lhaceinbey@yahoo.com
authors.forename: L
authors.initials: L
authors.lastname: Hacein-Bey
authors.forename: P N
authors.initials: PN
authors.lastname: Varelas
mesh_terms: D000328:Adult; D001099:Arachnoid / Q000000981:diagnostic imaging* / Q000293:injuries*; D004677:Encephalocele / Q000150:complications* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000209:etiology*; D011859:Radiography; D012421:Rupture / Q000150:complications / Q000000981:diagnostic imaging