[Odontoid fracture: Long-term subarachnoid hemorrhage after anterior screw fixation. Case report and literature review].

Odontoid fractures have been classified by Anderson and D'Alonzo into three main categories. The most unstable injuries, type II fractures involve the base of the odontoid peg at the junction with the C2 body. Due to the proximity of vital neural structures, fracture of the odontoid process may result in instability and fatal neurological damage. Treatment aims to re-establish stability of the atlanto-axial complex by restoring the odontoid process. This may be achieved by conservative or surgical treatment. Anterior screw fixation of the odontoid peg is an interresting alternative surgical option but this technique has a significant complication rate. However, vascular injury is very rare with three case reported in the literature: one case of an intracranial vertebral artery (VA) injury, one case of a cervical internal carotid artery (ICA) injury and one case of anterior pseudoaneurysm of the spinal artery branch. We report a new case of long term vascular injury after screw fixation revealed by a subarachnoid hemorrhage. We discuss the incidence, the mechanisms of injury and the conditions necessary for the occurrence of this complication.