Digitate intravascular appendages and aneurysm of the vein of Galen.

Peculiar intravascular appendages were found in a case of aneurysm of the vein of Galen. Such appendages consisted of finger-like polypoid growths which protruded within the lumen of ectatic cerebral veins and arteries. They were solid, relatively large, and non-branching. Histologically, their structure was comparable to that of a vessel wall, but was concentrically laminated around the longitudinal axis. Some appendages were associated with thrombi. It is suggested that appendages of this kind probably represent secondary vascular malformations, that they are likely to develop in reaction to abnormal hemodynamic strains upon the vessel walls, and that they might be thrombogenic and, therefore, potentially beneficial for patients with arteriovenous shunts.