Elsevier

The Lancet Neurology

Volume 6, Issue 9, September 2007, Pages 816-825
The Lancet Neurology

Review
Comparison of endovascular and surgical treatments for intracranial aneurysms: an evidence-based review

https://doi.org/10.1016/S1474-4422(07)70217-XGet rights and content

Summary

Intracranial aneurysms can be treated with endovascular or surgical techniques. We provide an objective comparison of these treatments, using data from single-centre studies, multicentre studies with and without independent outcome ascertainment, and randomised clinical trials. We compared the outcomes of patients who were candidates for endovascular treatment, surgical treatment, or both. In patients with ruptured intracranial aneurysms, rates of aneurysm obliteration were higher, and need for second treatment was lower, after surgery than after endovascular treatment. However, in observational studies and randomised trials, outcome at discharge, at 2–6 months, and at 1 year, and later survival, were all better after endovascular treatment than after surgery. The results suggest that the higher rates of incomplete obliteration and retreatment after endovascular treatment do not affect patients' clinical outcome. In observational studies of patients with unruptured intracranial aneurysms, discharge outcomes were better and hospital costs were lower after endovascular treatment than after surgery. These patients showed no difference between the two treatments in 1-year outcomes and later rebleeding, although few data were available for this comparison.

Introduction

Intracranial aneurysms are focal dilatations in medium-sized arteries. They are a substantial health problem, and affect roughly 2% of the population worldwide.1 In 1937, Walter Dandy performed the first surgical treatment of an aneurysm using a vascular clip designed by Harvey Cushing.2, 3 Subsequent advances in neurosurgical techniques (eg, the development of operating microscopes, microsurgical instruments, improved clips, neuroanaesthesia, and perioperative management for complications such as hydrocephalus and symptomatic vasospasm) enabled neurosurgeons to treat most cerebral aneurysms, and surgery was the predominant treatment for almost four decades. Attempts were made to place iron particles, detachable balloons, and platinum coils into intracranial aneurysms through endovascular routes1 but, although such treatment was successful in some patients, its applicability was limited by high rates of particle migration, balloon deflation, and aneurysm rupture. In the late 1980s, Guglielmi and colleagues4 developed a device in which a soft platinum coil soldered onto a stainless steel wire was successfully delivered through a microcatheter into the aneurysm sac—the coil mass protected against rupture by buffering the haemodynamic stress against the fundus of the aneurysm.5, 6 The development and subsequent approval of such detachable coils by the US Food and Drug Administration (FDA) in 1995 mandated a reassessment of intracranial aneurysm treatment.

Initially, endovascular treatment was used in patients who were thought to be poor candidates for surgical treatment,1, 7 such as people who: had severe neurological deficits; had an aneurysm in the posterior circulation or in the cavernous segment of internal carotid artery; were aged 75 years or over; presented 3–10 days after aneurysm rupture; or had active cerebral vasospasm. Over the past decade, treatment of intracranial aneurysms has evolved rapidly, with new developments in endovascular treatments such as detachable coils and intravascular stents. However, the use of these treatments varies considerably among institutions and practitioners. National organisations and medical institutions are trying to ensure that the new technology is adapted in a uniform and evidence-based way. Over the past 5 years, as endovascular treatments have become more widely available, practitioners have been constantly seeking comprehensive and objective sources of information to help them select patients for a particular treatment. In this article, we review: comparisons of endovascular treatment with surgery; how evidence is being incorporated into professional guidelines; and implications for the future, including deficiencies in some of the present data. Panel 1 shows how we have classified surgical and endovascular treatments.

Section snippets

Pathophysiology and rates of aneurysm rupture

Intracranial aneurysms result from degeneration of the arterial wall, which is caused by congenital and acquired medical defects8 and factors such as hypertension and cigarette smoking.9, 10 Enlargement and rupture of aneurysms results from interplay between continuing degeneration and haemodynamics. A major rupture can be preceded by infiltration of the artery wall by fibrin and leucocytes, bleb formation, and a minor haemorrhage.9, 10 Some intracranial aneurysms rupture early in their

Single-centre comparisons

An important point to note before we compare treatments for intracranial aneurysms is that some patients are candidates for surgery only or endovascular treatment only, whereas for other patients, either treatment is an acceptable option. This distinction depends on the clinical condition of the patient, the morphology and location of the aneurysm, and institutional expertise. Single-centre studies of endovascular and surgical treatments14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 (table 1)

Recommendations from professional organisations

There have been several sets of guidelines about endovascular treatments for aneurysms since September 1995, when the FDA approved Guglielmi detachable coils for treatment of high-risk or inoperable ruptured and unruptured brain aneurysms.40 Panel 2 summarises the recommendations made in these guidelines, together with recommendations made by published reports (table 2).

In 1997, guidelines from the Canadian Neurosurgical Society41 recommended early surgery for aneurysm treatment unless the

Implications for clinical practice

On the basis of results from ISAT, we estimated that if a new treatment for ruptured aneurysms had a 6% higher rate of discharge of patients home from hospital after subarachnoid haemorrhage than did an older procedure, use of the new procedure for 20% and 50% of patients with subarachnoid haemorrhage could lead to yearly savings of $11·4 million and $28·6 million, respectively (Qureshi AI, unpublished). However, the cost savings and reduction in death and disability are obscured by the

Conclusions

Endovascular treatment has been incorporated into the treatment of patients with subarachnoid haemorrhage who are poor candidates for surgical treatment. Since the emergence of endovascular treatments, reports such as ISAT have supported the idea that endovascular treatment is a valid alternative for many patients (table 2). However, the definition of these patients is arbitrary, and the decision to use endovascular treatment for unruptured intracranial aneurysms can depend on the views and

Search strategy and selection criteria

We based the review on personal knowledge of the subject supplemented by data from multicentre randomised trials, non-randomised controlled studies with independent outcome ascertainment, and selected observational studies. The information was identified with multiple searches of Medline from January, 1985, to May, 2007, by cross-referencing key words of “intracranial aneurysms”, “subarachnoid haemorrhage”, “embolization”, and “detachable coils”. Only papers published in English were

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