Published online before print December 29, 2004, doi: 10.1161/01.STR.0000153059.41663.60
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
(Stroke. 2005;36:211.)
© 2005 American Heart Association, Inc.
Advances in Stroke 2004 |
Stroke Review
Advances in Interventional Neuroradiology 2004
From the Department of Neuroradiology (D.P.), University of Western Ontario, London, Canada; the Karolinska Institute (T.A., M.S.), Stockholm, Sweden; the Department of Interventional Neuroradiology and Neurosurgery (P.L.), Clinica Medica Belgrano, Buenos Aires, Argentina; and Intervascular Neurosurgery (M.N.), Fujita Health University, Japan.
Correspondence to Dr David M. Pelz, Director, University of Western Ontario, Neuroradiology, London, Ontario, Canada. E-mail cathy.lockhart{at}lhsc.on.ca
Key Words: Advances in Stroke • cerebrovascular disorders • endovascular therapy • intracranial aneurysm • intracranial arterial disease • radiology
 |
Introduction |
|---|
 Top Introduction Carotid StentingStenting of Intracranial DiseaseStrokeAneurysmsArteriovenous MalformationsVasospasmImaging AdvancesReferences |
|---|
The year 2004 in interventional neuroradiology has been distinguished by the steady accumulation of evidence to validate the efficacy of therapeutic procedures, such as carotid angioplasty and stenting (CAS) for cerebrovascular atherosclerosis. There is increasing momentum to design trials that will validate the role of endovascular therapy in the treatment of acute stroke and other cerebrovascular disorders. Practice patterns continue to evolve as evidence-based principles are applied to interventional therapy.
|
Carotid Stenting |
|---|
|
TopIntroductionCarotid StentingStenting of Intracranial DiseaseStrokeAneurysmsArteriovenous MalformationsVasospasmImaging AdvancesReferences |
|---|
In September 2004, the US Food and Drug Administration approved the use of stents for the treatment of atherosclerotic disease of the carotid bifurcation. This approval was based on data from the industry-supported Acculink for Revascularization of Carotids in High Risk patients (ARCHeR)1 registry and the Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE) trial.2 ARCHeR showed a 10% complication rate for CAS in 581 high-risk patients compared with a 15% complication rate derived from the carotid endarterectomy (CEA) literature. SAPPHIRE was a randomized control trial (RCT) comparing CAS to CEA in 334 high-risk patients. Primary end points were the cumulative incidence of death, stroke, or myocardial infarction within 30 days and death or ipsilateral stroke between 31 days and 1 year. The overall rate of primary end points was 39% lower in the CAS group, and CAS resulted in complication rates for all adverse events
CEA in both symptomatic and asymptomatic patients. The authors believe they have proven their hypothesis that CAS with distal protection is not inferior to CEA in high-risk patients. Criticisms of the study include the large proportion of asymptomatic patients, bias favoring CAS due to unequal randomization, the inclusion of many patients with recurrent stenoses after prior CEA, small sample size, and controversial end points, such as myocardial infarction and cranial nerve palsy.3 The evidence is also gathering that distal embolic-protection devices are essential to minimize complications in CAS.4,5 The Carotid Revascularization Endarterectomy versus Stent Trial (CREST) in North America is accelerating enrollment, and there are at least 3 European RCTs underway comparing CAS to CEA.6 The Asymptomatic Carotid Surgery Trial (ACST)7 showed that immediate CEA in asymptomatic patients <75 years of age with >70% stenosis halved the 5-year stroke rate from 12% with medical therapy to 6% (assuming a 3.1% surgical risk). Although similar to results of prior studies,8 this will undoubtedly fuel the trend toward treatment of asymptomatic disease with CAS. Despite the mounting evidence, there is still no long-term data on CAS to rival that of CEA, particularly in symptomatic patients who are not at high surgical risk. |
Stenting of Intracranial Disease |
|---|
|
TopIntroductionCarotid StentingStenting of Intracranial DiseaseStrokeAneurysmsArteriovenous MalformationsVasospasmImaging AdvancesReferences |
|---|
Dedicated flexible cerebrovascular stents are now available to treat intracranial atherosclerotic stenoses, and 2 studies9,10 showed that this could be successfully performed in >95% of cases with complication rates <10%. Symptomatic restenosis, however, occurs in up to 67%, particularly with vertebral artery ostial lesions.9 The development of drug-eluting stents may address this problem. This procedure remains relatively high risk and requires careful patient selection.
|
Stroke |
|---|
|
TopIntroductionCarotid StentingStenting of Intracranial DiseaseStrokeAneurysmsArteriovenous MalformationsVasospasmImaging AdvancesReferences |
|---|
Mechanical devices for clot removal in acute stroke are becoming more sophisticated, and Phase I of the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) Trial evaluated results in 28 patients treated within 6 hours of stroke onset. The device, a combination of microcatheter, retriever, and balloon catheter, was able to reopen 12 (43%) occluded arteries alone and 6 more (64%) with additional intra-arterial (IA) recombinant tissue plasminogen activator (rtPA).11 There was, however, a high incidence of intracranial hemorrhage (43%), although all were asymptomatic. Overall, 9 of the 18 patients (50%) with vessel recanalization had significant clinical recovery, compared with none of the 10 patients who showed no recanalization. Preliminary results from Phase II show that the therapeutic window can be extended to 8 hours, and in the 114 patients studied, successful revascularization was obtained in 53.5%, with a serious procedural complication rate of 3.5%.12 Clot fragmentation based on laser technology (endovascular photoacoustic recanalization) has also been applied in 34 acute stroke patients.13 The overall recanalization rate was 41% with a 5.9% symptomatic hemorrhage rate and only 1 serious procedure-related complication. The combination of IV and IA rtPA remains intuitively attractive to facilitate rapid delivery of thrombolytic agents, and the Interventional Management of Stroke (IMS) Study14 showed that this strategy is feasible, but the results in 80 patients treated within 3 hours of the event showed little significant improvement in outcome compared with the placebo and treatment groups of the NINDS trial.15 IMS II is already underway and will also evaluate the use of a low-intensity ultrasound system (EKOS MicroLys). An RCT of IV/IA versus standard IV therapy is being planned.
|
Aneurysms |
|---|
|
TopIntroductionCarotid StentingStenting of Intracranial DiseaseStrokeAneurysmsArteriovenous MalformationsVasospasmImaging AdvancesReferences |
|---|
Technological developments continue for the treatment of wide-necked and complex cerebral aneurysms. Experience is accumulating with use of the Neuroform (Boston Scientific/Target) device for stent-assited coiling of these lesions,16,17,18 and although occlusion rates can be improved, there are still significant problems with thrombo-embolic complications (up to 10%) and deployment difficulties. The stents are expensive, and there is no conclusive evidence for superiority over the balloon remodeling techniques employed successfully in Europe and elsewhere for many years. Covered stents are being developed for both intracranial and extracranial use.19 Promising new coil designs include those with a synthetic polymeric hydrogel coating to improve aneurysm packing density20 and a variable detachable system21 to minimize instrumentation inside the aneurysm lumen. The use of Onyx remains popular in Europe,22 but concerns about aneurysm recanalization (10% by 1 year) have resulted in waning interest in this technique in North America. As devices for cerebrovascular therapy become more complex and potentially thrombogenic, a better understanding and manipulation of the coagulation system is mandatory to prevent thromboembolic complications.23 There is ongoing debate about the impact of the International Subarachnoid Aneurysm Trial (ISAT)24 and pleas for more rigorous scientific evaluation of new coils and devices rather than simple reliance on case series, registries, and manufacturers claims.25
|
Arteriovenous Malformations |
|---|
|
TopIntroductionCarotid StentingStenting of Intracranial DiseaseStrokeAneurysmsArteriovenous MalformationsVasospasmImaging AdvancesReferences |
|---|
The techniques of endovascular therapy of cerebral arteriovenous malformations (AVMs) have changed little in the last few years, but the efficacy and the indications for these procedures are coming under increasing scrutiny. Although relatively high rates for complete AVM obliteration (22%) with n-butyl cyanoacrylate continue to be reported,26 preoperative or preradiosurgical embolization remain the primary therapeutic strategies. In a large series of 339 preoperative procedures,27 there was an 11% risk of death or permanent neurological deficit from the interventional therapy alone, with poor angiographic results in almost 8% of patients. There is a perception that the procedure may be overutilized in the US and that the benefits of decreased operative blood loss and normal perfusion breakthrough bleeding may only be realized in complex lesions, and that the risks do not justify use in more surgically straightforward AVMs.28 In another series of 118 patients, 88% of whom had undergone prior embolization, radiosurgery resulted in a 77% 5-year cure rate with an annual risk of adverse event rate (hemorrhage or stroke) of 3.9%.29 There is still no evidence that palliative embolization alone confers any benefit to patients, and partial embolization may actually increase the risk of hemorrhage.28 A retrospective analysis of 398 patients with unruptured brain AVMs (290 surgery and/or endovascular, 108 untreated) followed for an average of almost 5 years showed an annual bleeding rate of only 1.5% in the untreated patients, and that therapy resulted in a hemorrhage rate equal to that of untreated patients but with higher morbidity.30 The quest goes on to better understand the genetic background of this disease and to use this knowledge to improve and individualize treatments.31
|
Vasospasm |
|---|
|
TopIntroductionCarotid StentingStenting of Intracranial DiseaseStrokeAneurysmsArteriovenous MalformationsVasospasmImaging AdvancesReferences |
|---|
Post-hemorrhagic vasospasm continues to challenge those who treat cerebral aneurysms, and there is conflicting evidence as to whether there is any relationship of vasospasm severity to surgical clipping or endovascular coiling.32,33 The efficacy of traditional "Triple-H" therapy has been questioned,34 and old techniques such as multiple IA papaverine infusions have been revisited with some success.35 IA nimodipine36 and nicardipine37 have shown promise in small numbers of patients. Transdermal nitropaste38 and shunting of hemorrhagic cerebrospinal fluid through lumbar drains39 have been shown to reduce the degree of vasospasm and to improve outcome scores. Balloon angioplasty, however, remains the cornerstone of interventional management despite the risks of vessel dissection and rupture. Although conventional digital subtraction angiography (DSA) is the gold standard for diagnosing vasospasm, computed tomographic angiography (CTA) and CT perfusion techniques are becoming popular, less invasive screening alternatives.40,41
|
Imaging Advances |
|---|
|
TopIntroductionCarotid StentingStenting of Intracranial DiseaseStrokeAneurysmsArteriovenous MalformationsVasospasmImaging AdvancesReferences |
|---|
Rotational 3D DSA is now a standard feature of neuroangiographic units, and "3D roadmap" functionality may soon be available to extract the most information from imaging data sets to help guide interventional procedures.42 Improvements in X-ray detector technology may soon allow simultaneous CT cross-sectional imaging from angiographic units. Three-dimensional computational fluid dynamics will help us understand why aneurysms recanalize, enlarge, and rupture after interventional treatment.43 There is increasing reliance on the less invasive modalities to diagnose disease, plan treatment, and to predict therapeutic response. An evidence-based analysis of procedures used for the diagnosis of carotid stenosis44 showed that duplex ultrasound is the most cost-effective stand alone investigation for carotid stenosis, and that the addition of magnetic resonance angiography led to a marginal increase in quality-adjusted life-years gained but at a prohibitive cost. Duplex ultrasound with quantitative computer-assisted indices for carotid plaque analysis can predict the likelihood of distal embolization and neurological complications from CAS.45 DSA is being replaced by CTA as the sole diagnostic procedure before cerebral aneurysm therapy in some centers.46
Received November 18, 2004; accepted December 1, 2004.
|
References |
|---|
|
TopIntroductionCarotid StentingStenting of Intracranial DiseaseStrokeAneurysmsArteriovenous MalformationsVasospasmImaging AdvancesReferences |
|---|
1. Proceedings of the 29th Annual Meeting of the Society of Interventional Radiology (SIR). Phoenix, Ariz; March 2004.
2. Yadav JS, Wholey MH, Kuntz RE, Fayad P, Katzen BT, Mishkel GJ, Bajwa TK, Whitlow P, Strickman NE, Jaff MR, Popma JJ, Snead DB, Cutlip DE, Firth BG, Ouriel K; Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy Investigators. Protected carotid-artery stenting versus endarterectomy in high-risk patients. N Engl J Med. 2004; 351: 1493–1501.
3. Cambria RP. Stenting for carotid-artery stenosis. N Engl J Med. 2004; 351: 1565–1567.
4. Mas JL, Chatellier G, Beyssen B; EVA-3S Investigators. Carotid angioplasty and stenting with and without cerebral protection: clinical alert from the Endarterectomy Versus Angioplasty in Patients With Symptomatic Severe Carotid Stenosis (EVA-3S) Trial. Stroke. 2004; 35: e18–e20.[CrossRef][Medline] [Order article via Infotrieve]
5. Reimers B, Schluter M, Castriota F, Tubler T, Corvaja N, Cernetti C, Manetti R, Picciolo A, Liistro F, Di Mario C, Cremonesi A, Schofer J, Colombo A. Routine use of cerebral protection during carotid artery stenting: results of a multicenter registry of 753 patients. Am J Med. 2004; 116: 217–222.[CrossRef][Medline] [Order article via Infotrieve]
6. Brown MM. Carotid artery stenting: evolution of a technique to rival carotid endarterectomy. Am J Med. 2004; 116: 273–275.[Medline] [Order article via Infotrieve]
7. MRC Asymptomatic Carotid Surgery Trial (ACST) Collaborative Group. Prevention of disabling and fatal strokes by successful carotid endarterectomy in patients without recent neurological symptoms: a randomised controlled trial. Lancet. 2004; 363: 1491–1502.[CrossRef][Medline] [Order article via Infotrieve]
8. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. Endarterectomy for asymptomatic carotid artery stenosis. JAMA. 1995; 273: 1421–1428.
9. SSYLVIA Study Investigators. Stenting of Symptomatic Ahterosclerotic Lesions in the Vertebral or Intracranial Arteries (SSYLVIA): study results. Stroke. 2004; 35: 1388–1392.
10. Jiang WJ, Wang YJ, Du B, Wang SX, Wang GH, Jin M, Dai JP. Stenting of symptomatic M1 stenosis of middle cerebral artery. an initial experience of 40 patients. Stroke. 2004; 35: 1375–1380.
11. Gobin YP, Starkman S, Duckwiler GR, Grobelny T, Kidwell CS, Jahan R, Pile-Spellman J, Segal A, Vinuela F, Saver JL. MERCI 1: a phase 1 study of mechanical embolus removal in cerebral ischemia. Stroke. 2004; 35: 1–6.
12. Grobelny T, Akhtar N, Rymer M, Boutwell C, Bettinger I, Schwartzman M, Arkin S, Weinstein C, Gruenenfelder B, Summers D, Thrutchley D, Jones C. Intracranial thrombolysis outcome analysis within the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) Trial. (Abstract.) Stroke. 2004; 35: 300–301.
13. Berlis A, Lutsep H, Barnwell S, Norbash A, Wechsler L, Jungreis CA, Woolfenden A, Redekop G, Hartmann M, Schumacher M. Mechanical thrombolysis in acute stroke with endovascular photoacoustic recanalization. Stroke. 2004; 35: 1112–1116.
14. IMS Study Investigators. Combined intravenous and intra-arterial recanalization for acute ischemic stroke: the interventional management of stroke study. Stroke. 2004; 35: 904–911.
15. NINDS rt-PA Stroke Study Group. Tissue plasminogen activator for acute ischemic stroke. N Engl J Med. 1995; 333: 1581–87.
16. Fiorella D, Albuquerque FC, Han P, McDougall CG. Preliminary experience using the neuroform stent for the treatment of cerebral aneurysms. Neurosurgery. 2004; 54: 6–17.[CrossRef][Medline] [Order article via Infotrieve]
17. Benitez R, Silva MT, Klem J, Veznedaroglu E, Rosenwasser RH. Endovascular occlusion of wide-necked aneurysms with a new intracranial micrsostent (Neuroform) and detachable coils. Neurosurgery. 2004; 54: 1359–1368.[CrossRef][Medline] [Order article via Infotrieve]
18. Chow MH, Woo HW, Masaryk TJ, Rasmussen PA. A novel endovascular treatment of a wide-necked basilar apex aneurysm by using a Y- configuration, double stent technique. AJNR Am J Neuroradiol. 2004; 25: 509–512.
19. Felber S, Henkes H, Weber W, Miloslavski E, Brew S, Kuhne D. Treatment of extracranial and intracranial aneurysms and arteriovenous fistulae using stent grafts. Neurosurgery. 2004; 55: 631–638.[Medline] [Order article via Infotrieve]
20. Cloft HJ, Kallmes DF. Aneurysm packing with HydroCoil Embolic System versus platinum coils: initial clinical experience. AJNR Am J Neuroradiol. 2004; 25: 60–62.
21. Lubicz B, Leclerc X, Gauvrit JY, Lejeune JP, Pruvo JP. Selective endovascular treatment of intracranial aneurysms with sapphire coils. AJNR Am J Neuroradiol. 2004; 25: 1368–1372.
22. Molyneux AJ, Cekirge S, Saatci I, Gal G. Cerebral Aneurysm Multicenter European Onyx (CAMEO) Trial: results of a prospective observational study in 20 European centers. AJNR Am J Neuroradiol. 2004; 25: 39–51.
23. Bendok BR, Padalino DJ, Levy EI, Qureshi AI, Guterman LR, Hopkins LN. Intravenous abciximab for parent vessel thrombus during basilar apex aneurysm coil embolization: case report and literature review. Surg Neurol. 2004; 62: 304–311.[CrossRef][Medline] [Order article via Infotrieve]
24. Byrne JV. Impact of the International Subarachnoid Aneurysm Trial on radiology. Br J Radiol. 2004; 77: 903–905.
25. Raymond J, Guilbert F, Weill A, Roy D, LeBlanc P, Gevry G, Chagnon M, Collet JP. Safety, science and sales: a request for valid clinical trials to assess new devices for endovascular treatment of intracranial aneurysms. AJNR Am J Neuroradiol. 2004; 25: 1128–1129.
26. Yu SCH, Chan MSY, Lam JMK, Tam PHT, Poon WS. Complete obliteration of intracranial arteriovenous malformations with endovascular cyanoacrylate embolization: initial success and rate of permanent cure. AJNR Am J Neuroradiol. 2004; 25: 1139–1143.
27. Taylor CL, Dutton K, Rappard G, Pride GL, Replogle R, Purdy PD, White J, Giller C, Kopitnik TA Jr, Samson DS. Complications of preoperative embolization of cerebral arteriovenous malformations. J Neurosurg. 2004; 100: 810–812.[Medline] [Order article via Infotrieve]
28. Heros RC. Editorial: Embolization of arteriovenous malformations. J Neurosurg. 2004; 100: 807–809.[Medline] [Order article via Infotrieve]
29. Bollet MA, Anxionnat R, Buchheit I, Bey P, Cordebar A, Jay N, Desandes E, Marchal C, Lapeyre M, Aletti P, Picard L. Efficacy and morbidity of arc-therapy radiosurgery for cerebral arteriovenous malformations: a comparison with the natural history. Int J Radiat Oncol Biol Phys. 2004; 58: 1353–1363.[Medline] [Order article via Infotrieve]
30. Mohr JP, Stapf C, Sciacca RR, Khaw AV, Mast H, Connolly ES, Pile-Spellman J. Natural history versus treatment outcome in patients with unruptured brain arteriovenous malformation (AVM). (Abstract.) Stroke. 2004; 35: 328.
31. Lawton MT, Stewart CL, Wulfstat AA, Derugin N, Hashimoto T, Young WL, Dacey RG, Selman WR, Findlay JM, Omahen DA. The transgenic arteriovenous fistula in the rat: an experimental model of gene therapy for brain arteriovenous malformations. Neurosurgery. 2004; 54: 1463–1471.[Medline] [Order article via Infotrieve]
32. Hoh BL, Topcuoglu MA, Singhal AB, Pryor JC, Rabinov JD, Carter BS, Ogilvy CS. Effect of clipping, craniotomy, or intravascular coiling on cerebral vasospasm and patient outcome after aneurysmal subarachnoid hemorrhage. Neurosurgery. 2004; 55: 779–789.[CrossRef][Medline] [Order article via Infotrieve]
33. Dehdashti R, Mermillod B, Rufenacht DA, Reverdin A, deTribolet N. Does treatment modality of intracranial ruptured aneurysms influence the incidence of cerebral vasospasm and clinical outcome? Cerebrovasc Dis. 2004; 17: 53–60.[CrossRef][Medline] [Order article via Infotrieve]
34. Treggiari MM, Walder B, Suter PM, Romand JA. Systematic review of the prevention of delayed ischemic neurological deficits with hypertension, hypervolemia and hemodilution therapy following subarachnoid hemorrhage. J Neurosurg. 2003; 98: 978–984.[Medline] [Order article via Infotrieve]
35. Liu JK, Tenner MS, Gottfried ON, Stevens EA, Rosenow JM, Madan N, MacDonald JD, Kestle JR, Couldwell WT. Efficacy of multiple intraarterial papaverine infusions for improvement in cerebral circulation time in patients with recurrent cerebral vasospasm. J Neurosurg. 2004; 100: 414–421.[Medline] [Order article via Infotrieve]
36. Biondi A, Ricciardi GK, Puybasset L, Abdenour L, Longo M, Chiras J, Van Effenterre R. Intra-arterial nimodipine for the treatment of symptomatic cerebral vasospasm after aneurysmal subarachnoid hemorrhage: preliminary results. AJNR Am J Neuroradiol. 2004; 25: 1067–1076.
37. Badjatia N, Topcuoglu MA, Pryor JC, Rabinov JD, Ogilvy CS, Carter BS, Rordorf GA. Preliminary experience with intra-arterial nicardipine as a treatment for cerebral vasospasm. AJNR Am J Neuroradiol. 2004; 25: 819–826.
38. Lesley WS, Lazo A, Chaloupka JC, Weigele JB. Successful treatment of cerebral vasospasm by use of transdermal nitroglycerin ointment (Nitropaste). AJNR Am J Neuroradiol. 2003; 24: 1234–1236.
39. Klimo P, Kestle JR, MacDonald JD, Schmidt RH. Marked reduction of cerebral vasospasm with lumbar drainage of cerebrospinal fluid after subarachnoid hemorrhage. J Neurosurg. 2004; 100: 215–224.[Medline] [Order article via Infotrieve]
40. Hoeffner EG, Case I, Jain R, Gujar SK, Shah GV, Deveikis JP, Carlos RC, Thompson BG, Harrigan MR, Mukherji SK. Cerebral perfusion CT: technique and clinical applications. Radiology. 2004; 231: 632–644.
41. Goldsher D, Schreiber R, Shik V, Tavor Y, Soustiel JF. Role of multisection CT angiography in the evaluation of vertebrobasilar vasospasm in patients with subarachnoid hemorrhage. AJNR Am J Neuroradiol. 2004; 25: 1493–1498.
42. Soderman M, Babic D, Andersson T. 3D-Roadmap. A new tool in interventional neuroradiology. Proceedings of the 56th Annual Meeting of the Scandinavian Neurosurgical Society, 2004.
43. Hoi Y, Meng H, Woodward SH, Bendok BR, Hanel RA, Guterman LR, Hopkins LN. Effects of arterial geometry on aneurysm growth: three-dimensional computational fluid dynamic study. J Neurosurg. 2004; 101: 676–681.[Medline] [Order article via Infotrieve]
44. Buskens E, Nederkoorn PJ, Buijs-Van Der Woude T, Mali WP, Kappelle LJ, Eikelboom BC, Van Der Graaf Y, Hunink MG. Imaging of carotid arteries in symptomatic patients: cost-effectiveness of diagnostic strategies. Radiology. 2004; 233: 101–112.
45. Biasi GM, Froio A, Diethrich EB, Deleo G, Galimberti S, Mingazzini P, Nicolaides AN, Griffin M, Raithel D, Reid DB, Valsecchi MG. Carotid plaque echolucency increases the risk of stroke in carotid stenting: the Imaging in Carotid Angioplasty and Risk of Stroke (ICAROS) Study. Circulation. 2004; 110: 756–762.
46. Hoh BL, Cheung AC, Rabinov JD, Pryor JC, Carter BS, Ogilvy CS. Results of a prospective protocol of computed tomographic angiography in place of catheter angiography as the only diagnostic and pretreatment planning study for cerebral aneurysms by a combined neurovascular team. Neurosurgery. 2004; 54: 1329–1342.[CrossRef][Medline] [Order article via Infotrieve]
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||