Vertebral Artery Pseudoaneurysm Resulting in Embolic Stroke as a Complication of Posterior C1 Lateral Mass Screw Fixation: A Case Report.

Abstract

Current literature supports posterior screw instrumentation of the C1 lateral mass as a reliable procedure for treating many occipitocervical and atlantoaxial pathologies with a low incidence of vertebral artery and neurologic injury and a high accuracy rate for screw placement1-6. The rate of vertebral artery injury from Cl lateral mass screw fixation is unknown1,2. Bransford et al. reported no neurologic or vascular complications in a large series, despite cases of suboptimal screw placement2. However, the variable and unique C1 anatomy can make precise instrumentation challenging with the rare potential for vascular and neurologic injury. Iatrogenic vertebral artery injury can have serious consequences, including excessive acute bleeding, arteriovenous fistula, pseudoaneurysm, occlusion, narrowing, or dissection. These defects may remain asymptomatic or lead to massive bleeding, transient ischemic attack, stroke, or death, occurring at variable time intervals up to several years after surgery1,7,8. Vertebral artery occlusion or vertebrobasilar thromboembolic events typically result in brainstem or cerebellar dysfunction7. To the best of our knowledge, this is the first report of a vertebral artery pseudoaneurysm as a complication of posterior C1 lateral mass fixation that resulted in delayed embolic stroke. The patient’s family was informed that data concerning the case would be submitted for publication, and they provided consent. An eighty-two year-old man with a history of a type-II odontoid fracture, which had been treated with a posterior cervical C1-C2 fusion with lateral mass and pedicular fixation 3.5 years ago, presented to our institution after a fall. There had been no reported intraoperative difficulties during the initial surgery. The patient had been neurologically intact both preoperatively and postoperatively. An immediate postoperative computed tomography (CT) scan had demonstrated that the left C1 lateral mass screw had violated the …