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

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Abstract
The diminishing threshold for the application of neuroimaging leads to an increasingly frequent diagnosis of previously asymptomatic arteriovenous malformations (AVMs). In such a context, it is warranted to define the criteria that make a lesion potentially hazardous so that neurosurgeons and patients reach a decision concerning how to manage the AVM. In addition to the proposed grading system for AVMs, which assesses the risk of an actual treatment procedure, several studies have been concerned with the evaluation of angioarchitectural features. The goal of the present study is to demonstrate the significance of feeding vessel pedicle aneurysms, especially those found in infratentorial AVMs. To determine the incidence of associated aneurysms, the authors reviewed an unselected cohort of 242 consecutive patients with AVMs managed between 1989 and 1999. Within this group were 240 patients who were treated by surgery, endovascular techniques, or a combination of both. Of these patients, 216 harbored a supratentorial and 24 an infratentorial AVM. Two additional patients with supratentorial AVMs underwent treatment of ruptured aneurysms without treatment of the AVMs. In six of the patients with supratentorial AVMs, proximal flow-related aneurysms were found on major feeding arteries, only one of which had caused hemorrhage. In only one patient were there additional distal feeding vessel pedicle aneurysms near the AVM, one of which had caused a major hemorrhage. In contrast, four of 24 patients with infratentorial AVMs had distal feeding artery pedicle aneurysms. Three of these aneurysms had caused hemorrhage. 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 vessel pedicle aneurysms appear to occur more frequently in conjunction with infratentorial AVMs, which justifies aggressive management to prevent incidences of morbidity associated with rupture of the aneurysm.