[Persistent proatlantal segmental artery: description of a case].

A 42 years old man, suffering from pulsating headache, episodes of loss of consciousness and motor difficulty of the right arm, had an angiographic examination, showing a malformation of the right carotid, which connected the external carotid artery with the basilar artery. The AA. have discussed the theories about this condition, trying to find an embryo-genetic explanation. They have evaluated the clinical aspects caused by the abnormality considering mainly its circulatory defect, considering also the possible association with intracranial aneurysm caused by modification of the normal circulation in the brain stem and neck arteries.