ROTATIONAL VERTEBRAL ARTERY-OCCLUSION - A MECHANISM OF VERTEBROBASILAR INSUFFICIENCY

OBJECTIVE: Symptomatic dynamic changes in blood flow secondary to vert ebral artery compression with rotational head motion are evaluated in a series of patients as a cause for posterior circulation transient is chemic attacks. These cases are classic examples of rotational vertebr al artery occlusion and allow for the discussion of the anatomic basis , angiographic features, and treatment options. ILLUSTRATIVE CASES: In our series, symptoms of vertebrobasilar insufficiency were reproducib le with rotational head movement. Compression of the vertebral artery was demonstrated angiographically. The correct site of occlusion of th e vertebral artery: was apparent only by dynamic angiography with prog ressive head rotation. All of the patients presented in the illustrati ve cases had occlusion at the C2 level; however, one patient had been previously misdiagnosed and another had an additional site of occlusio n. The anatomic course of the vertebral artery is described in additio n to the sites of rotational occlusion. CONCLUSION: Rotational vertebr al occlusion is an important cause of vertebrobasilar symptoms, which may lead to permanent neurological deficit if left undiagnosed. Dynami c angiography is the established method of diagnosis. Great care must be taken to avoid misdiagnosing the site of occlusion or missing a sec ond occlusive site. For this reason, it is crucial to have a thorough understanding of the anatomic course of the vertebral artery and the m uscular and tendinous insertions, which may cause rotational occlusion . The decision for treatment must be based on the site of occlusion as well as the assessment of the patient as a surgical candidate. A revi ew of the literature reveals that surgical treatment is effective and must be considered to avoid further morbidity.