[Giant thrombosed aneurysm of the left vertebral artery developing in the fourth ventricle].

A case of giant, thrombosed, non haemorrhagic aneurysm of the distal portion of the left vertebral artery is reported. The patient came to medical attention with an acute cervical pain after a minimal cervical traumatism and a diagnosis of torticollis from rheumatologic cause was made. In fact, a few weeks before, he had suffered three episodes of right homonymous hemianopsia.