Proatlantal intersegmental arteries of external carotid artery origin associated with Galen's vein malformation.

Carotid basilar anastomoses can occasionally persist beyond the embryonic period. These anomalies are most often incidentally detected in adulthood, during workups for unrelated pathologies. Persistence of the proatlantal intersegmental arteries is a rare form of primitive carotid-basilar anastomoses. Bilateral proatlantal inter- segmental arteries are an extremely rare occurrence, of which only 3 cases have been reported in the literature. An analysis of vascular anomalies associated with Galen's vein malformations revealed 3 children in whom persistence of type II proatlantal arteries was seen. These included one child in whom proatlantal arteries were persistent bilaterally. We report the clinical and angiographic findings and discuss the embryologic and therapeutic implications of this unique association.