Posterior Inferior Cerebellar Artery Originating from the Jugular Branch of the Ascending Pharyngeal Artery.

The variation in which the posterior inferior cerebellar artery arises from the hypoglossal branch of the ascending pharyngeal artery is thought to be related to the remnant of the primitive hypoglossal artery, and is referred to as a primitive hypoglossal artery variant. Cases in which the posterior inferior cerebellar artery arises from the jugular branch of the ascending pharyngeal artery are extremely rare. The authors present a case of a 50-year-old male with vertebral artery dissection who had this extremely rare variation bilaterally. The patient also had several rare variations of the intracranial vessels. This posterior inferior cerebellar artery arising from the jugular branch of the ascending pharyngeal artery may have developed due to the anastomosis between the meningeal and the pial vessels of the posterior fossa. Alternatively, an unknown primitive anastomotic artery may have passed through the jugular foramen. Genetic factors may play an important role in the presence of this anomalous vessel.