Diagnosis and management of vertebral artery stenosis

Approximately one‐quarter of ischaemic strokes involve the posterior or vertebrobasilar circulation.1,,2 Stenosis of the vertebral artery can occur in either its extra‐ or intracranial portions, and may account for up to 20% of posterior circulation ischaemic strokes.3–,6 Stenotic lesions, particularly at the origin of the vertebral artery, are not uncommon. In an angiographic study of 4748 patients with ischaemic stroke, some degree of proximal extracranial vertebral artery stenosis was seen in 18% of cases on the right and 22.3% on the left.7 This was the second most common site of stenosis after internal carotid artery stenosis at the carotid bifurcation. Such stenotic lesions are now potentially treatable by endovascular techniques.8 In marked contrast with carotid artery stenosis, the optimal management of vertebral artery stenosis has received limited attention, and is poorly understood. This partly reflects difficulties in imaging the vertebral artery adequately, and limited surgical treatment options. Recent improvements in imaging and the arrival of vertebral artery angioplasty, however, have opened up new opportunities for intervention in this disease. We review vertebral artery anatomy, what is known of the natural history of vertebral artery disease, the role of imaging in the diagnosis of vertebral artery stenosis, and treatments for vertebral artery stenosis. The vertebral artery arises from the supraposterior aspect of the first part of the subclavian artery. In 6% of cases, the left vertebral artery arises directly from the aortic arch. Unlike the internal carotid artery, which is an almost direct extension of its parent vessel the common carotid artery, the vertebral artery branches almost at right angles to its feeding vessel. The vertebral artery, being 3–5 mm in diameter, is of much smaller relative calibre than the subclavian, with only a small amount of subclavian blood flow normally being directed into …