[Persistent fetal carotid-vertebrobasilar anastomoses].

The primitive trigeminal, otic (acoustic), hypoglossal, and proatiantal intersegmental arteries are persistent fetal anastomoses between the carotid and vertebrobasilar circulations. These fetal anastomoses regress at roughly the rate at which the posterior communicating and vertebral arteries develop. The purpose of this study is to review the persistent fetal carotid-vertebrobasilar anastomoses with MRI and DSA.