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Intracranial aneurysm and carotid artery stenosis.

In this issue of the Southern Medical Journal, Navaneethan et al (1) present a timely discussion of a difficult and uncommon dilemma of concomitant atherosclerotic cervical carotid artery stenosis and a giant middle cerebral artery aneurysm. Over the past decade, treatment strategies for both of these conditions have evolved considerably and continue to change as technical advancements are made.

Medical management with antiplatelet therapy versus surgical management with carotid endarterectomy (CEA) has been studied extensively in randomized prospective trials of carotid artery stenosis. Symptomatic patients with high-grade carotid artery stenosis (70 to 99%) with recent hemispheric or retinal transient ischemic attacks or nondisabling strokes had significantly better outcomes after CEA than comparable patients treated medically. (2) More modest benefits from CEA compared with medical therapy have been shown in symptomatic patients with lesser degrees of stenosis (50 to 69%), and for asymptomatic patients with moderate to severe stenosis. (3-5)

More limited studies have been performed for assessment of the role of carotid artery stenting (CAS), (6) and suggest that the safety of CAS may be equivalent to CEA. A phase III Carotid Artery versus Endarterectomy Stenting Trial (CREST) sponsored by the National Institute of Neurologic Disorders and Stroke (NINDS) is currently accruing patients to compare the efficacy of CEA versus CAS.

Treatment of cerebral aneurysms traditionally has been performed via craniotomy and microsurgical techniques. Over the past decade, endovascular techniques including coiling and stenting have been developed as alternative treatments for some aneurysms. The goals of aneurysm treatment include reducing risks of hemorrhage and minimizing neurologic morbidity and death. Cerebral aneurysms are typically classified by their maximal diameter as small (less than 1 cm), large (1 to 2.5 cm) or giant (greater than 2.5 cm). Prospective studies have suggested that larger aneurysms carry higher risk of subarachnoid hemorrhage, (7) and giant aneurysms such as the one presented in this issue of the Journal have a poor natural history and are technically challenging to treat.

Factors affecting whether to treat an aneurysm include anatomy, patient age, neurologic condition, medical comorbidities, and whether or not the aneurysm has ruptured. Determining which technique to use, microsurgery or an endovascular approach, is best determined through interdisciplinary collaboration between neurosurgeons and interventional neuroradiologists with expertise in these techniques. The International Subarachnoid Aneurysm Trial (ISAT), (8) a randomized prospective trial of over 2000 European patients with ruptured aneurysms, suggested better neurologic outcomes for patients treated with endovascular coiling compared with microsurgical clipping, but other studies have demonstrated that the durability of endovascular treatment of cerebral aneurysms may be considerably worse than microsurgical treatment and that rates of incomplete aneurysm obliteration or recurrence may be as high as 40 to 50%. (9)

As one can see, there remains considerable controversy with regard to the ideal treatment strategies for both intracranial aneurysms and occlusive atherosclerotic cervical carotid disease. When they are identified simultaneously in the same patient, optimal management for both of these conditions are even less clearly defined, but a few reports have addressed this issue specifically. (10, 11) These studies report identification of intracranial aneurysms in 1 to 3% of patients evaluated for cervical carotid artery atherosclerotic disease, and that the presence of one of these conditions, in general, should not alter the management of the other.

At our institution, I suspect that this patient may have been treated with a CEA first and at a later date, craniotomy for microsurgical clipping of the aneurysm. One cannot argue with the good outcome achieved with the techniques of carotid artery stenting and aneurysm stenting and coiling achieved by the authors. The long-term effectiveness and durability of the coiling and stenting are less established, and long-term follow up is advisable. Creative and thoughtful application of new techniques to complex conditions such as the patient described by the authors can yield excellent outcome for challenging situations.

References

1. Naveenthan SD, Kannan VS, Osowo A, et al. Concomitant intracranial aneurysm and carotid artery stenosis: a therapeutic dilemma. South Med J 2006;99:757-758.

2. North American Symptomatic Carotid Endarterectomy Trial (NASCET) Collaborators. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N Engl J Med 1991;325:445-453.

3. Barnett HJ, Taylor DW, Eliasziw M, et al. Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis: North American Symptomatic Carotid Endarterectomy Trial Collaborators. N Engl J Med 1998;339:1415-1425.

4. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. Endarterectomy for asymptomatic carotid artery stenosis. JAMA 1995;273:1421-1428.

5. Hobson RW II, Weiss DG, Fields WS, et al. Efficacy of carotid endarterectomy for asymptomatic carotid stenosis: the Veterans Affairs Cooperative Study Group. N Engl J Med 1993;328:221-227.

6. Yadav JS, Wholey MH, Kuntz RE, et al. Protected carotid-artery stenting versus endarterectomy in high-risk patients. N Engl J Med 2004;351:1493-1501.

7. International Study of Unruptured Intracranial Aneurysms (ISUIA) Investigators. Unruptured intracranial aneurysms: risk of rupture and risks of surgical intervention. N Engl J Med 1998;339:1725-1733.

8. Molyneux A, Kerr R, Stratton I, et al, International Subarachnnoid Hemorrhage Aneurysm Trial (ISAT) Collaborative Group. International Subarachnnoid Hemorrhage Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with rupture intracranial aneurysms: a randomized trial. Lancet 2002;360:1267-1274.

9. Brilstra EH, Rinkel GJ, van der Graaf Y, et al. Treatment of intracranial aneurysms by embolization with coils: a systematic review. Stroke. 1999;30:470-476.

10. Kappelle LJ, Eliasziw M, Fox AJ, et al. Small, unruptured intracranial aneurysms and management of symptomatic carotid artery stenosis: North American Symptomatic Carotid Endarterectomy Trial Group. Neurology 2000;55:307-309.

11. Carvi Y, Nievas MN, Haas E, et al. Unruptured large intracranial aneurysms in patients with transient cerebral ischemic episodes. Neurosurg Rev 2003;26:215-220.
Another flaw in the human character is that everybody wants to build
and nobody wants to do maintenance.
--Kurt Vonnegut


Michael R. Chicoine, MD

From the Department of Neurosurgery, Washington University School of Medicine, St Louis, MO.

Reprint requests to Michael R. Chicoine, MD. Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8057, St Louis, MO 63110. Email: mchicoine@pol.net

Accepted March 24, 2006.
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Title Annotation:Editorial; medical research
Author:Chicoine, Michael R.
Publication:Southern Medical Journal
Geographic Code:1U600
Date:Jul 1, 2006
Words:1022
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