ROTATIONAL OBSTRUCTION OF NONDOMINANT VERTEBRAL ARTERY AND ISCHEMIA

A 70-year-old man presented with repeated vertebrobasilar insufficienc y for 3 years. Four-vessel angiography revealed complete occlusion of the nondominant left vertebral artery on head turning to the right. Th ree-dimensional computerized tomography angiography demonstrated atlan toaxial joint dislocation when the head was turned to the right, in ac cordance with simultaneous occlusion of the left vertebral artery caus ed by stretching of the artery at C1-2. After posterior fixation of C1 -2 by a Halifax interlaminar fixation system, the patient had no furth er episodes. Hemodynamic function associated with nondominant vertebra l artery occlusion contributed to the symptoms in this case.