Clinical experiences of ruptured posteroinferior cerebellar artery aneurysms and anatomical analysis in the cadaver in a single center of China.

Objective: Posteroinferior cerebellar artery (PICA) aneurysms are uncommon and have not been well investigated previously. We report our series of 29 ruptured PICA aneurysms with surgical treatment along with the description of the surgical anatomy of the PICA to the lower cranial nerves in cadaveric specimen.

Methods: All patients with ruptured PICA aneurysms who were surgically treated at the First Affiliated Hospital of Soochow University during the period from January 1995 to December 2008 were reviewed retrospectively. Data relating to clinical, radiological, and intraoperative findings were analyzed. Forty formalin-fixed cerebellar hemispheres provided the material for the study of describing the detailed surgical anatomic relationship of the PICA to the lower cranial nerves.

Results: In our series, ruptured PICA aneurysms reached an incidence of 2.35% of all ruptured intracranial aneurysms. There were 13 aneurysms (44.8%) located in the proximal segment, and 16 (55.2%) located in the distal segment. Of these, 89.7% were saccular, 6.9% fusiform, and 3.4% dissecting aneurysms. Usually, the surgical outcome was influenced by Poor admission grade, the presence of obstructive hydrocephalus and associated distal AVM. In cadaveric specimen, 17.5% of PICAs passed between the glossopharyngeal and vagus nerves, 7.5% between the vagus and accessory nerves, and 62.5% through the rootlets of the accessory nerve.

Conclusion: This report summarizes the presentation and outcome of a large series of 29 patients with ruptured PICA aneurysms, and we conclude that ruptured PICA with surgical treatment usually gets well recovered. The study does, however, also demonstrate that the anatomic relationship of the PICA and lower cranial nerves is somehow variable and irregular. Recognition of the findings in cadaveric dissection is essential in treating lesions of this region.