Vascular Surgery and Neurosurgery

The most common vascular or neurosurgical procedures done to prevent stroke are carotid endarterec-tomies. In 1989, there were approximately 70,000 carotid endarterectomies performed in the United States, and approximately half of these were for asymptomatic carotid stenosis. At that time, the value of surgery for stroke prevention was controversial. The Asymptomatic Carotid Artery Study (ACAS), the European Carotid Surgery Trial (ECST), and the North American Symptomatic Carotid Endarterect-omy Trial (NASCET) demonstrated the benefit of surgery for both asymptomatic and symptomatic carotid artery stenosis. In the NASCET, carotid endarterectomy decreased the risk of stroke over 2 years by 17% compared to medical management in symptomatic patients with 70-99% stenosis. With greater than 80% internal carotid stenosis, carotid endarterectomy provided an absolute risk reduction of 11.6% in stroke and death end points over a 3-year time period. A smaller benefit (6.5% absolute risk reduction over 5 years) was evident for carotid endarterectomy in symptomatic patients with 5069% stenosis compared to medical management. The results of the ECST were similar. In asymptomatic individuals with high-grade stenosis (>70%) reported in the ACAS, the relative risk reduction over 5 years was 53%, but the absolute risk reduction was only 1.2% per year. Thus, the number of strokes prevented by carotid endarterectomy in asymptomatic stenosis of >70% is similar to the benefit seen with symptomatic stenosis of 50-69%.

Surgical repair of other vascular abnormalities is also possible. Extracranial aneurysms of the carotid arteries may be surgically repaired to prevent rupture. Intracranial aneurysms are usually clipped, but en-dovascular therapies are increasingly utilized for surgically inaccessible or giant aneurysms; detachable coils may be inserted into the vessels (Fig. 9), or balloons may be inserted. These techniques may lead to successful clot formation and obstruction of blood flow into the aneurysm, thus reducing the risk of rupture. Surgical removal of AVMs may be quite successful, although large AVMs may also require adjunctive endovascular therapy. For example, large and complex AVMs supplied by several vessels may need to be obliterated partially by intraarterial glue therapy prior to surgical resection. In patients with paradoxical cerebral embolization from lower extremity deep venous thrombosis, an inferior vena cava filter (Greenfield filter) may be inserted, or the intracardiac shunt may be surgically repaired.

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