Fetal carotid-vertebrobasilar anastomoses: persistent hypoglossal artery associated with further variations of the circle of Willis.

During a routine dissection of the head and neck regions, a right persistent hypoglossal artery was found in a male individual who had died at approximately 40 years of age. This variation is associated with hypoplasia of the right and left vertebral arteries and absence of the right posterior communicating artery. Clinical implications of this variation are described. The article includes a review of the fetal carotid-vertebrobasilar anastomoses, their embryological explanation and associated pathologies.