A rare carotid-basilar anastomosis traversing the jugular foramen: origin and clinical implications.

This report describes imaging in a patient with a unique unnamed carotid-basilar anastomosis, where the entry into the skull was via the jugular foramen. There were associated findings of absent right and hypoplastic left vertebral arteries and an aberrant right subclavian artery. We speculate that the persistent anastomosis is developmentally related to the jugular branch of the ascending pharyngeal artery. Clinical implications of the course via the jugular foramen are also discussed.