Rotational vertebral artery occlusion at C1-C2.

Compromise of blood flow in the vertebral arteries associated with head rotation is generally considered an uncommon cause of vertebrobasilar insufficiency. It can occur at virtually any level of the cervical spine. We present two cases of transient total occlusion of the left vertebral artery at the atlantoaxial joint during head rotation to the right. In one case, the contralateral vertebral artery was severely hypoplastic, and surgical C1-C2 fusion to protect the larger left vertebral artery resulted in relief of the clinical symptoms related to head rotation.