[Claude Bernard-Horner syndrome revealing spontaneous aneurysm of the vertebral artery].

False aneurysms of the extracranial vertebral artery (FAVA) are rare because of the path of the artery at the level of the transverse holes. They can be secondary to penetrating cervical trauma, spontaneous in the course of an angiopathy such as Ehlers-Danlos syndrome, or iatrogenic. We report the case of a 31-year-old woman who presented a syndrome of Claude Bernard-Horner related to a spontaneous FAVA. The angioscanner confirmed the diagnosis and the patient underwent successful surgical treatment of the false aneurysm with ligature of the vertebral artery. Outcome was favorable.