Bilateral Vertebral Artery Aneurysms at the Atlantoaxial Joint Level Causing Recurrent Stroke.

Vertebral arteries (VAs) are vulnerable to mechanical stress between the atlas and axis, and subsequent VA dissection can cause posterior circulation infarction. We herein present a rare but informative case of bilateral VA aneurysms that caused recurrent stroke. The localization of the aneurysms and dynamic angiography with neck movement suggested a pathogenesis related to chronic mechanical injury of the VAs, though no skeletal abnormality was detected. The recurrences stopped and both aneurysms shrank after neck collar fixation and after the combination use of antithrombotics. For patients with posterior circulation infarction of unknown origin, a careful evaluation of VAs with physicians paying special attention to the atlantoaxial joint level is therefore recommended.