Anterolateral decompression of the atlantoaxial vertebral artery for symptomatic positional occlusion of the vertebral artery. Case report.

A case of repeated vertebrobasilar ischemic attacks related to head rotation (bow hunter's stroke) is reported. With head rotation of 45 degrees or more to the right, the patient would become lightheaded and feel as if she were going to lose consciousness. Angiography performed when head rotation was to the right revealed mechanical compression of the left vertebral artery at the foramen transversarium of the axis and an occluded right vertebral artery. Untethering of the vertebral artery as it passed through the foramen transversarium of the atlas in this case completely relieved the patient's symptoms. The authors conclude that contralateral vertebral artery occlusion predisposed this patient to symptomatic vertebrobasilar insufficiency secondary to ipsilateral vertebral artery mechanical stenosis induced by head turning.