Ischemic symptoms induced by occlusion of the unilateral vertebral artery with head rotation together with contralateral vertebral artery dissection--case report.

We report a 45-year-old woman whose unilateral vertebral artery (VA) was potentially occluded with head rotation at the C1-C2 level and her ischemic symptoms suddenly appeared because of contralateral VA dissection. She noticed first pain around the posterior part of her neck on the right side, and then dizziness when turning the head to the right side. The dizziness disappeared immediately after her head returned to the natural position. Digital subtraction angiography (DSA) showed a string sign of the right VA. DSA and computed tomography angiography (CTA) showed high grade extrinsic compression of the left VA at the C1-C2 level with head rotation more than 90 degrees to the right. Three-dimensional (3D) CTA also showed clearly kinking of the left VA at the C2 neuroforamina. Her symptoms disappeared completely with conservative therapy, and recanalization of the right VA was also confirmed by 3D-CTA. 3D-CTA was thought to be valuable to diagnose and manage the rotational compression of the artery. VA dissection must be remembered to differentially diagnose the etiology of transient attacks of posterior circulation ischemia due to rotational contralateral VA occlusion.