Non-atherosclerotic fusiform cerebral aneurysms

Background: Fusiform cerebral aneurysms are dilatations of the entire circumference of a segment of cerebral artery, usually considered due to atherosclerosis in adults. They are relatively thick-walled and elongated, causing neural compression or ischemia when discovered. We have noted a subset of fusiform cerebral aneurysms that vary from this common description. Patients: Out of a series of 472 intracranial aneurysms treated over 11 years, 11 patients between the ages 16 and 67 years (mean age 37) were identified who had discrete fusiform aneurysms unassociated with generalized cerebral atherosclerosis, connective tissue disorder or inflammation. Three presented with hemorrhage, six with neural compression by the aneurysm and two were discovered incidentally. Results: Nine aneurysms were located in the posterior circulation, the other two in the intracranial carotid artery. Their mean length and width were 16.3 and 11 mm, respectively. Three aneurysms contained thrombus. The eight aneurysms that were exposed surgically were partly or substantially thin-walled with normal appearing parent arteries. Eight were treated with proximal occlusion and three were circumferentially "wrapped". Parent artery occlusion caused one death and one mild disability and the remaining patients made good recoveries (follow-up 0.5 - 10 years). Conclusions: There is a subset of cerebral aneurysms with discrete fusiform morphology, apparently unrelated to cerebral atherosclerosis or systemic connective tissue disease, thin-walled in part or whole, more common in the vertebrobasilar system, and possessing a risk of rupture. Treatments currently available include proximal occlusion or aneurysm "wrapping", different approaches than neck-clipping or endovascular coiling of side-wall saccular cerebral aneurysms that leave the parent artery intact.