Recommendations for the Management of Patients With Unruptured Intracranial Aneurysms
To the Editor:
I read with great interest a recent article concerning recommendations for the management of unruptured intracranial aneurysms, published both in Stroke and in Circulation.1 The authors state, “Thus far, all natural history studies have been performed on patients selected for conservative management [italics added].” The reason for this seems to be that the recommendations are based almost exclusively on the results obtained from the International Study of Unruptured Intracranial Aneurysms (ISUIA). However, it is well known that the results of the ISUIA are in conflict with those of other studies.
The above-quoted statement is not true. In Helsinki, patients with unruptured aneurysms diagnosed before 1979 were not treated surgically.2 3 4 5 This gave us the possibility for a long-term follow-up of patients with unruptured aneurysms but without surgical selection of cases, and thus there was no bias caused by surgery. Our first cases have been reported as case reports, but the results of patient series have been repeatedly published with improved use of statistics since 1970, as the number of patients and follow-up years increased.2 3 4 5 The follow-up has been prospective, without loss of cases during the follow-up.
For my detailed opinions for potential sources of bias of the ISUIA, see our last follow-up study.5 In brief, patients of the ISUIA were collected from the time period when unruptured intracranial aneurysms were operated on, and the retrospective part of the follow-up study did not include all patients with conservative treatment who also were very likely older than those who were excluded due to surgical treatment. In addition, patients with a prior subarachnoid hemorrhage were younger than those without, and it was not analyzed statistically whether aneurysm group really was an independent risk factor for aneurysm rupture when age was taken into account.
Our patients with unruptured aneurysms and long-term follow-up (total of 2575 person-years, median 19.7 years per patient) showed that current cigarette smoking, size of unruptured aneurysm, and age, inversely, were significant predictors for subsequent aneurysm rupture.5 Because the prevalence of cigarette smoking is now decreasing in North America and Europe, the risk of rupture possibly also diminishes. However, this cannot explain the very low rupture rates of the ISUIA. Therefore, I am worried because operation on incidental aneurysms <10 mm in diameter is not recommended, and also because analysis of additional radiological findings of aneurysm or family history of aneurysms, or waiting for specific symptoms (ie, rupture of aneurysm), is recommended before a decision is made to operate.1
According to our long-term follow-up,5 I recommend surgical or endovascular treatment for all aneurysms <10 mm in patients aged <50 (to 60) years if there are no contraindications. The indication for surgery is higher—even in older patients—if the patient is smoking, since cigarette smoking hastens the growth of preexisting aneurysms, which is associated with an increased risk of aneurysm rupture.6 I also recommend operating on small aneurysms in young (<50 to 60 years) patients with either polycystic kidney disease (PKD) or systemic lupus erythematous (SLE). Among our 142 patients, we had 2 patients with PKD; 1 of them died of aneurysm rupture. Two young women (aged 22.6 and 35.0 years at diagnosis) with SLE who were not cigarette smokers or hypertensives suffered aneurysm rupture after the aneurysms had increased 5 mm and 8 mm in diameter, respectively. One of them with an incidental aneurysm died of this aneurysm rupture 3.8 years after its diagnosis, at age 38.8 years.
- Copyright © 2001 by American Heart Association
Bederson JB, Awad IA, Wiebers DO, Piepgras D, Haley EC Jr, Brott T, Hademenos G, Chyatte D, Rosenwasser R, Caroselli C. Recommendations for the management of patients with unruptured intracranial aneurysms: a statement for healthcare professionals from the Stroke Council of the American Heart Association. Stroke. 2000;31:2742–2750; Circulation. 2000;102:2300–2308.
Juvela S, Poussa K, Porras M. Factors affecting formation and growth of intracranial aneurysms: a long-term follow-up study. Stroke. In press.
Dr Juvela’s experience with epidemiological studies of unruptured aneurysms makes him one of the world’s foremost authorities on this subject. His published work was extensively reviewed by our writing group and formed the basis for several of our Recommendations.
It should be noted that we did not suggest conservative management of patients with the smallest incidental aneurysms in patients without prior SAH. Rather, we stated that while “treatment rather than observation cannot generally be advocated···special consideration for treatment should be given to young patients in this group [italics added].” This language differs significantly from the conclusions reached by the authors of the ISUIA. It was specifically chosen because of concerns about potential selection bias in the ISUIA that could have led to underestimating the rupture rate in patients selected for conservative management. This was discussed in detail in the Recommendations.
Even if one accepts Dr Juvela’s assertion that the ISUIA was wrong about natural history, an annual bleeding risk of 1% to 2% means that 50 to 100 operations must be performed to prevent 1 SAH the first year. Clearly, other factors must be considered. I am gratified that Dr Juvela has reached essentially the same conclusions we did. Namely, that for the smallest incidentally discovered aneurysms in patients without prior SAH, age is the most important factor in deciding whom to treat.
Although we have learned a great deal about unruptured aneurysms, many diverse and important questions still remain. For example, what is the influence of aneurysm morphology on bleeding risk? What factors underlie the significantly higher prevalence of intracranial aneurysms in populations such as the Japanese and those studied by Dr Juvela? Do these factors also influence apparent rupture rates? What is the effect of incomplete versus complete endovascular coiling on bleeding risk of a previously unruptured aneurysm? What is the true cognitive deficit rate after surgery? What is the demonstrable impact on quality of life of harboring a known unruptured aneurysm? Who should be screened for aneurysms, and how should conservatively treated aneurysms be followed?
My experience as a cerebrovascular surgeon and as the chair of this writing group lead me to believe that the data do not support blanket statements about any category of unruptured intracranial aneurysm. I believe treatment should be considered for all “young” patients regardless of aneurysm size, for all symptomatic aneurysms, and for any patients or aneurysms with other factors (ie, prior SAH from another aneurysm, family or genetic history, certain aneurysm morphologies) that predispose to rupture. Most importantly, management decisions must include experienced cerebrovascular surgeons at aneurysm centers that offer a full range of treatment options.