[Type II proatlantal artery with unusual origin of the occipital artery feeding of a type IV dural arteriovenous fistula: case report]. / Artère proatlantale de type II avec origine atypique d'une artère occipitale alimentant une fistule artérioveineuse durale de type IV : cas clinique.

CASE REPORT: We report the case of a 49 year-old woman, who presented with an intracranial haemorrhage. During cerebral angiography investigations, we observed an unusual vertebral artery that originated from the external carotid artery and an uncommon origin of the occipital artery from the vertebral artery feeding a dural arteriovenous fistula grade IV. This rare vertebral artery origin is probably the remnant of a type II proatlantal artery. In addition, the origin of the occipital artery evoked a vascular development disease including a dural arteriovenous fistula which may be the result. These multiple vascular abnormalities could be explained by embryologic disorders.