Basilar artery duplication associated with pituitary duplication: a new finding.

Pituitary duplication is a rare malformation, reported previously in approximately 18 patients. It is usually unsuspected before imaging, although it occurs most commonly in association with complicated midline and skull base anomalies. It is easily shown by MR imaging. Five new cases of pituitary duplication were diagnosed by using MR imaging studies reviewed at the Hospital for Sick Children. Among the many associated midline abnormalities, partial basilar artery duplication is a previously undescribed finding that we observed in all our cases. Cases of basilar artery duplication or fenestration are associated with altered flow dynamics, leading to a higher incidence of aneurysms. Periodic surveillance for this potential complication may be warranted.