Management of Aneurysmal Subarachnoid Hemorrhage: Is There a Light at the End of the Tunnel?
Disclosure: Dr. Caron has no conflicts.
Pub Date: Friday, January 23, 2009
Author: Jean-Louis Caron, MD
"The best way to predict the future is to invent it."
It is well documented that aneurysmal subarachnoid hemorrhage (SAH) is a devastating ailment responsible for approximately 5% of all strokes and affecting more than 30,000 Americans each year, the majority between the ages of 40 and 60 years.[1,2] There is no other medical affliction as deadly as a ruptured cerebral aneurysm, with population-based mortality as high as 45%.[3,4] If one survives the initial insult, one must then face the risk of rerupture, hydrocephalus, and the dreaded delayed ischemic deficit from vasospasm. It comes as no surprise, therefore, that more than 11,000 peer-reviewed manuscripts on the subject have been published in the last 10 years.
It has been 14 years since the first and only publication of guidelines for the management of aneurysmal subarachnoid hemorrhage by the Stroke Council of the American Heart Association (AHA). At the time of the initial publication, most, if not all, recommendations by the panel of experts were based on Class III evidence, and the goal of the original statement was to identify areas for further research and study. Since then, considerable technological advances in the field of imaging, critical care, and particularly endovascular catheters and detachable platinum coils have dramatically changed our treatment paradigms. It is with great anticipation that we await the publication of an updated statement by the Stroke Council of the American Heart Association for the management of aneurismal subarachnoid hemorrhage. To address the changes in management of aneurismal subarachnoid hemorrhage, the Stroke Council of the AHA formed a writing group to reevaluate the initial 1994 recommendations. The committee conducted a MEDLINE search, retaining all relevant literature published between June 1994 and November 2006, which met the criteria of a randomized trial or a nonrandomized, concurrent, cohort study, with the goal of addressing subjects that were covered in the initial guidelines. In the event that no study with a higher level of evidence was available, case series and nonrandomized, historical, cohort studies were reviewed.
In essence, these guidelines are the most comprehensive review of the available recent literature on the subject. It should be emphasized that guidelines are not "cookbooks," but the ultimate goal of this review is to suggest reasonable recommendations, as perceived by a panel of experts, using evidence-based medicine as a guide to improve clinical outcomes and identify further areas for research.
I was particularly interested in their approach, which is based on three important aspects: patient factors, aneurysm factors, and institutional factors. It is no surprise that the most important patient factor associated with a poor outcome is the severity of the initial hemorrhage. Despite advances in our knowledge of the initial deleterious events of an SAH, no effective treatment is available and more research in the field of neuroprotection is required.
Having survived the initial bleed, the patient must now face the risk of immediate or early rebleed. Treatment stratagems strongly support the role of early intervention to secure the aneurysm and to prevent rebleeding. The development of endovascular techniques, initially with detachable balloons and more recently the Guglielmi coils, have revolutionized our treatment approach in a most dramatic way. The publication of the initial results of the ISAT trial in 2002, with the 1-year follow-up update in 2005, has literally changed the landscape of aneurysm surgery.[7,8] Almost overnight, the number of patients treated by endovascular techniques went from under 10% to well over 90% in certain centers.[9,10] In summary, the ISAT trial selected 2,143 of 9,559 SAH patients for randomization to either endovascular embolization with Guglielmi detachable coils (GDC) or open surgical treatment of the ruptured aneurysm, based on the preoperative evaluation of the patient and aneurysm morphology, meaning that the aneurysm could be treated by either technique. The fact that so many patients were not suitable for randomization enhances the importance of both patient and aneurysm factors in the treatment paradigm and, ultimately, treatment outcome. It is our understanding that certain aneurysms, such as those in the posterior circulation, are better treated with endovascular techniques and that others, such as those on the middle cerebral artery, are more suitable for an open surgical approach. Similarly, the presence of an intracerebral clot, patient age, and presenting neurological status influenced the decision to operate or to coil. Therefore, the ISAT trial essentially became a study of SAH in younger patients, in good clinical grade, with small, anterior, circulation aneurysms. At 1 year, a negative outcome was defined as a modified Rankin Score of 3-6, that is, patients who were dead or dependant in activities of daily living. A significant difference was found between the two groups and the trial was stopped early: at 1 year, 22.7% of coiled patients were dependent or dead, compared to 30.6% of those subjected to surgery--an absolute risk reduction of 7.9% or a NNT of 13.
Should all aneurysms be treated this way? I would be hard pressed to think so, and I applaud the recommendations of the writing committee that, based on the available published evidence, patients should be treated in centers where both techniques are available. This ties in the institutional factors as determinant in patient outcome. Although there is an impetus to include endovascular surgical training within the teaching curriculum of the neurosurgical training programs, at this time the availability of endovascular surgery is still limited to a few centers across the country. Whether patients opt for open surgical clipping or endovascular obliteration of their aneurysm, the ultimate procedural outcome depends on the technical aptitude of the operator. In keeping with the findings of Johnston and others, that better outcomes are associated with higher volume centers with availability of endovascular techniques, it would seem reasonable to concentrate the care of SAH patients to "certified stroke centers" with the necessary skills and technology.[11,12]
It is surprising that compared to the advances in our understanding of the natural history, the prevention of rebleeding, and improved immediate procedural outcomes with new technologies, very little progress has occurred in the understanding and management of delayed ischemic deficits from vasospasm. The comprehensive review by the AHA writing group strongly underscores the importance of further research on the pathophysiology and molecular mechanisms of vascular injury. They also identify the need for further clinical trials of triple-H therapy, endovascular angioplasty, and intraarterial vasoactive agents and the need to continue our endeavor to find new innovative methods for prevention of vasospasm and neuroprotection.
The publication of the "Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage" is an excellent addition to the series on stroke management. Unfortunately, there is still a paucity of Class I evidence to guide treatment and care, and thus, guidelines for this disorder remain for the most part "opinion based" rather than "evidence based." It was a monumental task and the authors have given us a balanced review of the available evidence for the care of this disorder. I commend the writing committee for this important and much anticipated review.
- Graf CJ, Nibbelink DW. Cooperative study of intracranial aneurysms and subarachnoid hemorrhage. Report on a randomized treatment study. 3. Intracranial surgery. Stroke 1974;5(4):557-601.
- King JT, Jr. Epidemiology of aneurysmal subarachnoid hemorrhage. Neuroimging Clin N Am 1997;7(4):659-668.
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- Broderick JP, Brott TG, Duldner JE, et al. Initial and recurrent bleeding are the major causes of death following subarachnoid hemorrhage. Stroke 1994;25(7):1342-1347.
- Mayberg MR, Batjer HH, Dacey R, et al. Guidelines for the management of aneurysmal subarachnoid hemorrhage. A statement for healthcare professionals from a special writing group of the Stroke Council, American Heart Association. Stroke 1994;25(11):2315-2328.
- Guglielmi G, Vinuela F, Dion J, Duckwiler G. Electrothrombosis of sacular aneurysms via endovascular approach. Part 2: Preliminary clinical experience. J Neurosurg 1991;75(1):8-14.
- Molyneux A, Kerr R, Stratton I, et al. International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomized trial. Lancet 2002;360(9342):1267-1274.
- Molyneux A, Kerr R, Yu L, et al. International subarachnoid aneurysm trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomized comparison of effects on survival, dependency, seizures, rebleeding, subgroups, and aneurysm occlusion. Lancet 2005;366(9488):809-817.
- Maurice-Williams RS. Aneurysm surgery after the International Subarachnoid Aneurysm Trial (ISAT). J Neurol Neurosurg Psychiatry 2004;75(6):807-808.
- Lindsay KW. The impact of the International Subarachnoid Aneurysm Trial (ISAT) on neurosurgical practice. Acta Neurochir (Wien) 2003;145(2):97-99.
- Bardach NS, Zhao S, Gress DR, et al. Association between subarachnoid hemorrhage outcomes and number of cases treated at California hospitals. Stroke 2002;33(7):1851-1856.
- Berman MF, Solomon RA, Mayer SA, et al. Impact of hospital-related factors on outcome after treatment of cerebral aneurysms. Stroke 2003;34(9):2206-2207.
-- The opinions expressed in this commentary are not necessarily those of the editors or of the American Heart Association