Clinical significance of pedicle aneurysms on feeding vessels, especially those located in infratentorial arteriovenous malformations

Object. The diminishing threshold for the application of neuroimaging leads to an increasingly frequent diagnosis of previously asymptomatic arteriove nous malformations (AVMs). In such a context, it is warranted to define the criteria that make a lesion potentially hazardous so that neurosurgeons an d patients reach a decision concerning how to manage the AVM. In addition t o the proposed grading system for AVMs, which assesses the risk of an actua l treatment procedure, several studies have been concerned with the evaluat ion of angioarchitectural features. The goal of the present study is to dem onstrate the significance of feeding vessel pedicle aneurysms, especially t hose found in infratentorial AVMs. Methods. To determine the incidence of associated aneurysms, the authors re viewed an unselected cohort of 242 consecutive patients with AVMs managed b etween 1989 and 1999. Within this group were 240 patients who were treated by surgery, endovascular techniques, or a combination of both. Of these pat ients, 216 harbored a supratentorial and 24 an infratentorial AVM. Two addi tional patients with supratentorial AVMs underwent treatment of ruptured an eurysms without treatment of the AVMs. In six of the patients with supraten torial AVMs, proximal flow-related aneurysms were found on major feeding ar teries, only one of which had caused hemorrhage. In only one patient were t here additional distal feeding vessel pedicle aneurysms near the AVM, one o f which had caused a major hemorrhage. In contrast, four of 24 patients wit h infratentorial AVMs had distal feeding artery pedicle aneurysms. Three of these aneurysms had caused hemorrhage. Conclusions. Pedicle aneurysms on feeding vessels are frequently associated with hemorrhage (four of five cases in this series). In our cohort of 242 treated patients (240 treated for AVM and two for an aneurysm), feeding ves sel pedicle aneurysms appear to occur more frequently in conjunction with i nfratentorial AVMs, which justifies aggressive management to prevent incide nces of morbidity associated with rupture of the aneurysm.