[Angiographic examination of the vertebral artery at the atlantoxial joint during head rotation].

Stenosis or occlusion of the vertebral artery at the atlantoaxial joint associated with head rotation is generally considered an uncommon cause of vertebrobasilar insufficiency. This rotational contralateral (to the face) vertebral artery occlusion is considered to be a "physiological phenomenon". The purpose of the present article is to investigate whether stenosis or occlusion of the vertebral artery at the atlantoaxial joint really occurs with head rotation. The authors performed vertebral angiography both in the neutral position and with contralateral rotation of the head (about 80 - 90 degrees) on 39 patients (44 vertebral arteries), who didn't have any disease of the cervical region or of the posterior cranial fossa. The authors discussed the angiographic findings concerning the vertebral artery at the atlantoxial joint during contralateral rotation of the head. In some cases a vertebral artery was stretched with head rotation. However occlusion or stenosis of the vertebral artery was never found to occur at the atlantoaxial joint level in any of the cases. This result indicates that rotational vertebral artery occlusion is not a "physiological phenomenon". There may be many other developmental and degenerative factors contributing to this rotational occlusion, such as atherosclerosis, kinking, and tortuosity of the vertebral artery, hyperosteosis, tightness of the paravertebral muscle, stenosis of transverse foramen and the depth of the vascular groove of the atlas.