Rotational obstruction of nondominant vertebral artery and ischemia. Case report.

A 70-year-old man presented with repeated vertebrobasilar insufficiency for 3 years. Four-vessel angiography revealed complete occlusion of the nondominant left vertebral artery on head turning to the right. Three-dimensional computerized tomography angiography demonstrated atlantoaxial joint dislocation when the head was turned to the right, in accordance with simultaneous occlusion of the left vertebral artery caused by stretching of the artery at C1-2. After posterior fixation of C1-2 by a Halifax interlaminar fixation system, the patient had no further episodes. Hemodynamic function associated with nondominant vertebral artery occlusion contributed to the symptoms in this case.