Persistent embryonic veins in the arteriovenous malformations of the dura.

The basic anatomy of the arteriovenous malformations of the dura is similar to that of the internal carotid (pial) malformations, as the arterial feeders in both these lesions arise from the internal carotid artery in the embryo. The venous drainage occurs through definite channels into the major venous sinuses. Therefore, the dural and the pial malformations should be classified together. The scalp malformations have no features similar to these groups. The prominent occipital artery is not necessarily the primary feeder. Whenever a prominent occipital artery is seen, special efforts must be made to locate the primary dural feeders arising from the internal carotid artery.