[XII cranial nerve pseudoneurinoma due to spontaneous fibrous transformation of an aneurysm of the vertebral artery].

The authors report an exceptional case report of tumor like evolution of a completely thrombosed aneurysm of the right vertebral artery suggestive of neurinoma of the XII nerve. We describe CT, MRI, MR-angiography. The diagnosis has been established by pathologic study after surgical extraction. Our case demonstrate the possibility of growth of totally thrombosed aneurysms and we discuss various mechanisms.