Surgery of unruptured, asymptomatic aneurysms: a decision analysis

Cost-effectiveness of treatment of unruptured intracranial aneurysms in patients with a history of subarachnoid hemorrhage

RATIONALE AND OBJECTIVES

The study goal was to evaluate the cost-effectiveness of surgery and endovascular treatment of unruptured intracranial aneurysms in patients with a history of subarachnoid hemorrhage from a previous aneurysm, incorporating the results of the prospective International Study of Unruptured Intracranial Aneurysms.

MATERIALS AND METHODS

Using a Markov model, we performed a decision and cost-effectiveness analysis comparing surgery or endovascular treatment with no treatment. Twelve clinical scenarios were defined based on aneurysm size and location. Probabilistic sensitivity analyses were performed for 50- and 40-year-old cohorts. Treatment was considered to be cost-effective at an incremental cost-effectiveness ratio less than $100,000 per quality-adjusted life-year.

RESULTS

In 50-year-old patients, no treatment was the most cost-effective strategy for aneurysms located in the cavernous carotid artery. For aneurysms less than 7 mm located in the anterior circulation, no treatment was the most cost-effective strategy. Endovascular treatment was the most cost-effective option for 7- to 24-mm aneurysms, whereas surgery was the most cost-effective option for aneurysms of 25 mm or larger. For aneurysms less than 7 mm and located in the posterior circulation, endovascular treatment was the most cost-effective option, whereas surgery was the most cost-effective option for 7- to 12-mm aneurysms. No treatment was the most cost-effective strategy for aneurysms of 13 mm or larger.

CONCLUSION

For 50-year-old patients with a history of aneurysmal subarachnoid hemorrhage, treatment of unruptured aneurysms that are located in the cavernous carotid artery, or small (<7 mm) and located in the anterior circulation, or large (>or=13 mm) and located in the posterior circulation is ineffective or not cost-effective.

GUIDELINES FOR THE SURGICAL TREATMENT OF UNRUPTURED INTRACRANIAL ANEURYSMS

THE MANAGEMENT OF unruptured cerebral aneurysms remains one of the most controversial topics in neurosurgery. To this end, we discuss the diagnosis and estimated prevalence of these lesions as well as review the literature regarding the rate of rupture for cerebral aneurysms and risks of operative intervention. Our interpretation of the literature concludes that aneurysms are present in approximately 1% of the adult population, varying between less than 1% in young adults to 4% in the elderly. The yearly risk of subarachnoid hemorrhage for an unruptured intracranial aneurysm is approximately 1% for lesions 7 to 10 mm in diameter. Based on these assumptions, we recommend that 1) with rare exceptions, all symptomatic unruptured aneurysms should be treated; 2) small, incidental aneurysms less than 5 mm in diameter should be managed conservatively in virtually all cases; 3) aneurysms larger than 5 mm in patients younger than 60 years of age should be seriously considered for treatment; 4) large, incidental aneurysms larger than 10 mm should be treated in nearly all patients younger than 70 years of age; and 5) microsurgical clipping rather than endovascular coiling should be the first treatment choice in low-risk cases. Critical to our guidelines is collaboration by a highly experienced cerebrovascular team of microneurosurgeons and endovascular neurosurgeons working at a tertiary medical center with a high case volume and using a decision-making paradigm designed to offer only low-risk treatments. In certain patients for whom both treatment and natural history carry high risks, such as those with giant aneurysms, nonoperative management is typically elected.

The surgical treatment of cubital tunnel syndrome: a decision analysis

The objective of our study was to use decision analysis to compare four common surgical treatments for cubital tunnel syndrome: simple decompression of the cubital tunnel, medial epicondylectomy, anterior subcutaneous transposition and anterior submuscular transposition. The variables used for this decision analysis model were based on data from the literature. Extensive sensitivity analyses were carried out to test the impact of the values given to these variables on the outcome of the model. The highest expected utility, 0.973, was associated with simple decompression. The expected utility was 0.969 for subcutaneous transposition and 0.965 for submuscular transposition. Medial epicondylectomy had the lowest expected utility at 0.961. Simple decompression remained the preferred strategy in extensive one-way sensitivity analyses.

Treatment of unruptured intracranial aneurysms: decision and cost-effectiveness analysis

PURPOSE

To prospectively perform a decision and cost-effectiveness analysis of surgical and endovascular treatments of unruptured intracranial aneurysms, with incorporation of the results of the prospective International Study of Unruptured Intracranial Aneurysms.

MATERIALS AND METHODS

With use of a Markov model, a decision and cost-effectiveness analysis was performed for comparison of surgical or endovascular treatment with no treatment. Twelve clinical scenarios were defined on the basis of aneurysm size and location. Probabilistic sensitivity analyses were performed for 50- and 40-year-old patient cohorts. Treatment was considered to be cost-effective at an incremental cost-effectiveness ratio less than $100,000 per quality-adjusted life-year.

RESULTS

In 50-year-old patients, no treatment was the most cost-effective strategy for aneurysms located in the cavernous carotid artery. For aneurysms smaller than 7 mm located in the anterior circulation, no treatment was the most cost-effective strategy. Endovascular treatment was the most cost-effective option for 7-24-mm aneurysms, whereas surgical treatment was the most cost-effective option for aneurysms 25 mm or larger. For aneurysms smaller than 7 mm or 25 mm or larger located in the posterior circulation, no treatment was the most cost-effective strategy. Surgical treatment was the most cost-effective option for 7-12-mm aneurysms, whereas endovascular treatment was the most cost-effective option for 13-24-mm aneurysms.

CONCLUSION

For 50-year-old patients, treatment of aneurysms that are small (<7 mm), that are located in the cavernous carotid artery, or that are large (>or=25 mm) and located in the posterior circulation is ineffective or not cost-effective.

Preventive neurosurgery: population-wide check-up examinations and correction of asymptomatic pathologies of the nervous system

BACKGROUND

Prevention in healthcare is attracting more and more attention. Early identification and correction of anomalies harbouring the risk of a catastrophic event such as aneurysms is the principal rationale for brain check-up programmes. The other aim of preventive screening is to identify progressive lesions with little reversibility such as gliomas. The purpose of the current analysis is to review the frequency of the various incidental findings, the inherent risk and the therapeutic options. RATIONALE FOR CHECK-UP IMAGING AND PREVENTIVE TREATMENT: The average prevalence of asymptomatic intracranial benign tumours, aneurysms and carotid stenoses must be estimated as approximately 1% each. Meningiomas, aneurysms and carotid stenosis become more frequent with increasing age. Mainly vascular anomalies harbour a risk of a catastrophic event, i.e. carotid stenosis and intracranial aneurysms. Only gliomas potentially lose reversibility with time passing. The case of glioma appears to be lost since asymptomatic gliomas are extremely rarely identified on screening examinations, and on the other hand current treatment series do not support that infiltrating gliomas can be cured if only treated early enough. Treatment of the benign tumours, hydrocephalus and arachnoid cysts in the asymptomatic stage does not appear to provide any benefit. RATIONALE FOR GENETIC SCREENING: A number of intracranial tumours, vascular anomalies and degenerative changes are genetically determined. Examples are neurofibromatosis, tuberous sclerosis, von Hippel-Lindau disease and Rendu-Osler's disease. Although familial clustering of aneurysms is well known, the exact genetic anomaly is unknown and probably several genes play a role. Because of the variable penetrance of the inherited disorders with known genetic alterations, screening of affected families is recommended. The conditions are too rare to justify screening of the entire population. Apolipoprotein E genotype is the only accepted predictor of dementia. Routine screening APOE may be considered today, but is highly problematic due to the lack of clear consequences and the potentially negative psychological impact.

COSTS

Implementation of population-wide screening programmes and preventive measures would lead to a substantial additional financial burden. Brain-check-up programmes cannot be considered in isolation. Cardiovascular and oncological programmes would also have to be included from that point of view.

CONCLUSIONS

Population-wide screening with regard to intracranial aneurysms or carotid stenosis with non-invasive imaging techniques and preventive surgery/endovascular therapy can be justified, provided that treatment-associated morbidity is very low. There is no evidence for the rationale of screening for asymptomatic intracranial tumours, cysts or hydrocephalus. Genetic screening cannot be generally recommended, except among families affected by inherited conditions.

Endovascular Treatment of Unruptured Intracranial Aneurysms: Occurrence of Thromboembolic Events

OBJECTIVE:

The purpose of this study was to evaluate the frequency and causes of thromboembolic events associated with endovascular embolization of asymptomatic aneurysms. Correlations between radiological findings (aneurysm size, localization, embolization time, number of coils used, as well as patient age) were evaluated with the occurrence of thromboembolic events and clinical findings.

METHODS:

Sixty-eight patients treated for unruptured intracranial aneurysms (mean age, 49 yr) were evaluated. Hyperintense lesions on diffusion weighted imaging were analyzed in 50 patients. Aneurysm size was 3 to 15 mm.

RESULTS:

Complete occlusion of the aneurysms was achieved in 55 of 68 (82%). One patient had a transient paresis. There was one infarction and one aneurysm rupture during the procedure with no consecutive neurological symptoms. We found new hyperintense lesions in 21 of 50 (42%) diffusion weighted imaging studies. In 43% of these, there was only one lesion smaller than 2 mm. In 33%, there was more than one lesion less than 2 mm; in 19%, we found a lesion of 2 to 10 mm in size. In one case, a lesion greater than 10 mm occurred. There was no correlation between aneurysm location and the occurrence of lesions or among the number of coils used, the size of the aneurysm, patient age, or embolization time. Mortality rate was 0%, morbidity 4.0%. If the 18 aneurysms where no diffusion weighted imaging was obtained are included, morbidity is 2.9%.

CONCLUSION:

The high rate of thromboembolic events suggests that heparin is not sufficient to prevent ischemic lesions. An antiplatelet therapy, started before or during intervention, might diminish thrombus formation.

Outcome of Surgical Clipping of Unruptured Aneurysms as it Compares with a 10-Year Nonclipping Survival Period

OBJECTIVE

Recent studies on the natural history of unruptured intracranial aneurysms dictate that we reevaluate the risks and benefits of surgical intervention as it compares with the natural course. We analyzed the outcome of surgical clipping of a patient cohort with unruptured aneurysms as it compares with a 10 year nonclipping survival period on the basis of two previously published studies (International Study on Unruptured Intracranial Aneurysms and a study by Juvela et al. [36] from Helsinki).

METHODS

Data on 148 unruptured aneurysms in 116 consecutive surgically treated patients were prospectively recorded and retrospectively analyzed. The overall majority were diagnosed with cerebral angiography. Data analyzed included aneurysmal properties and clinical outcomes including surgical related mortalities and morbidities. The observed outcomes were compared with the expected outcome of a 10 year nonclipping survival period if the patient cohort was included in recently reported studies on unruptured aneurysms. More than 1 year follow-up was available in 93.1% (108) of patients and follow-up cerebral angiography was performed in 80% (93) of patients.

RESULTS

Mean age was 53.57 years. There were 25 (16.8%) small aneurysms (less than 7 mm), 70 (47.2%) aneurysms 7 to 12 mm in size, 41 (27.70%) large (13-24 mm), and 12 (8.10%) giant (>25 mm) aneurysms. Posterior circulation aneurysm comprised 13.51%. One hundred forty-three (96.62%) aneurysms were successfully clipped, and 3.37% were either wrapped or later coiled. Surgical-related mortality was 0.82% (1 patient because of air embolism). Surgical related permanent morbidity was 3.44% (4 patients) and transient surgical-related mild morbidities was 7.7% (9 patients). Immediate postsurgical good outcome (Glasgow Outcome Score = 4-5) was 87.93% (102 patients) and 95.68% in 3 months (111 patients). At 1 year, the modified Rankin scale scores were 0 to I = 102, II = 3, III = 2, IV = 1, and V = 0. Residual aneurysms were seen in none of the postoperative angiograms (93 patients). Using the chi method, the comparison of the expected to the observed mortality and morbidity revealed a statistically significant difference in the mortality in favor of surgical clipping (P = 0.034 when compared with the International Study on Unruptured Intracranial Aneurysms and P = 0.05 when compared with the Juvela et al. [36] study). There was no statistically significant difference in the permanent morbidity.

CONCLUSION

Studies on natural history of unruptured intracranial aneurysms suggest 10 year cumulative bleeding-related mortality and severe morbidity of no less than 7.5%. In our study, surgical clipping resulted in an 0.8% rate of mortality and 3.4% permanent morbidity. This suggests that surgical clipping has the potential of a superior outcome to the natural history of patients who have an estimated life expectancy of no less than 10 years.

Intracranial aneurysms at MR angiography: effect of computer-aided diagnosis on radiologists' detection performance

PURPOSE

To retrospectively evaluate the effect of computer-aided detection (CAD) on radiologists' performance in detection of intracranial aneurysms with magnetic resonance (MR) angiography.

MATERIALS AND METHODS

The institutional review board approved this study and did not require patient informed consent. Fifty maximum intensity projection MR angiograms in 50 patients were used for observer performance study. The group included 22 patients (age range, 43-86 years; mean, 60.2 years; 6 men and 16 women) with intracranial aneurysms and 28 patients (age range, 32-80 years; mean, 58.8 years; 10 men and 18 women) without aneurysms. The MR angiograms were obtained with three-dimensional time-of-flight 1.5-T MR imaging. Fifteen radiologists, including eight neuroradiologists and seven general radiologists, participated in the observer performance test. They interpreted the angiograms first without and then with the aid of the computer output by using an automated computerized scheme. The observers' performance without and with the computer output was evaluated with receiver operating characteristic analysis.

RESULTS

For all 15 observers, average area under the receiver operating characteristic curve (A(z)) value for detection of aneurysms was increased significantly from 0.931 to 0.983 (P = .001) when they used the computer output. A(z) values for general radiologists and neuroradiologists increased from 0.894 to 0.983 (P = .022) and from 0.963 to 0.984 (P = .014), respectively. Improvement in the performance of general radiologists in terms of the A(z) value was much greater than that of neuroradiologists. Performance of general radiologists with CAD (A(z) = 0.983) slightly exceeded that of neuroradiologists without CAD (A(z) = 0.963) (P = .048).

CONCLUSION

CAD improved neuroradiologists' and general radiologists' performance for detection of intracranial aneurysms with MR angiography; improvement was greater for general radiologists than it was for neuroradiologists.

Strategies for nonrandomized clinical research in hand surgery

Most clinical research questions in hand surgery may be effectively explored using a variety of nonrandomized study designs. The main advantage of any of these methods is that they are almost always more feasible than a prospective randomized, controlled trial. Although the level of evidence associated with nonrandomized designs is always lower than that of a randomized trial there are many instances in which the inferences based on these designs are sufficiently strong that important and meaningful conclusions can be made. The key considerations in using nonrandomized designs are to frame the research question appropriately and to recognize and anticipate the limitations and biases that are inherent to each one of these approaches.

A probabilistic and interactive decision-analysis system for unruptured intracranial aneurysms

OBJECT

The goal in this study was to develop an interactive, probabilistic decision-analysis system for clinical use in the decision to treat or observe unruptured intracranial aneurysms. Further goals were to enable users of the system to adapt decision-analysis methods to individual patients and to provide a tool for interactive sensitivity analysis.

METHODS

A computer program was designed to model the outcomes of treatment and observation of unruptured aneurysms. The user supplies probabilistic estimates of key parameters relating to a specific patient and nominates discount rate and quality of life adjustments. The program uses Monte Carlo discrete-event simulation methods to derive probability estimates of the outcomes of treatment and observation. Results are expressed as summary statistics and graphs. Discounted quality-adjusted life years are graphed using survival methods. Hierarchical simulations are used to enable investigators to perform probabilistic sensitivity analysis for one or multiple parameters simultaneously. The results of sensitivity analysis are expressed in graphs and as the expected value of perfect information. The system can be distributed and updated using the Internet.

CONCLUSIONS

Further research is required into the benefits of clinical application of this system. Further research is also required into the optimum level of complexity of the model, into the user interface, and into how clinicians and patients are likely to interpret results. The system is easily adaptable to a range of medical decision analyses.

The natural history of unruptured intracranial aneurysms

Since the publication of preliminary results from the International Study of Unruptured Intracranial Aneurysms in 1998 there has been a great deal of debate concerning the natural history of these lesions and their attendant risk of aneurysmal subarachnoid hemorrhage. Therefore, the authors reviewed a selected number of crucial studies concerning this topic to determine the best evidence-based estimate of a rupture rate for these lesions. Based on this analysis, the yearly risk of bleeding for an unruptured intracranial aneurysm is estimated to be approximately 1% for aneurysms 7 to 10 mm in diameter. This risk of rupture increases with aneurysm size and it likewise diminishes as the size of the lesion decreases. This general rule serves as a reasonable interpretation of the results reported in the current body of literature.

Unruptured intracranial aneurysms: natural history and management decisions

Aneurysmal subarachnoid hemorrhage (SAH) carries a grim prognosis, with high mortality and morbidity rates. The mortality rate in the first 30 days postrupture is estimated to be in the range of 40 to 50%, and almost half of the survivors will be left with a neurological deficit. Unlike patients with aneurysmal SAH, those with unruptured intracranial aneurysms usually experience no neurological deficit, and their treatment is prophylactic, aiming to reduce the risk of future bleeding and its consequences. The risk of rupture therefore assumes special importance when making decisions regarding which patient or aneurysm to treat.

In previous reports the risk of bleeding for unruptured aneurysms has been stated as approximately 2% per year. The retrospective part of the International Study of Unruptured Intracranial Aneurysms (ISUIA) reported very low annual bleeding rates (0.05–1%) and high surgical morbidity and mortality rates (8–18%), prompting discussion in which the benefits of prophylactic treatment in the majority of these lesions were questioned. Prospective data from the second part of the ISUIA recently included rupture rates ranging from 0 to 10% per year. The aim of this paper was to review the evidence that is currently available for neurosurgeons to use when making decisions regarding patients who would benefit from treatment of an unruptured intracranial aneurysm.

A randomized trial on the safety and efficacy of endovascular treatment of unruptured intracranial aneurysms is feasible

SUMMARY

The safety and efficacy of endovascular treatment of unruptured intracranial aneurysms remain undetermined. A randomized trial may be the best way to demonstrate the potential benefits of endovascular management. We propose a randomized, prospective, controlled trial comparing the incidence of subarachnoid haemorrage of patients treated by endovascular coiling as compared to conservative management. We would also study a composite outcome combining SAH and the morbidity of treatment. All patients with one or more unruptured aneurysm >> 3 mm eligible for endovascular treatment would be proposed to participate. The study would be conducted in 40-50 centres. The entire study would enrol 1800 patients, recruited over three years and followed for five years, but would be preceded by a feasibility study on 200 patients. A randomized trial comparing endovascular and conservative treatment could have an important impact on the clinical management of intracranial aneurysms.

Aneurysm observation versus intervention: a literature review

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating illness that affects persons at the peaks of their lives. The 1990s witnessed rapid growth in noninvasive vascular imaging technologies, which allowed safe diagnosis of unruptured saccular intracranial aneurysms. Presently, it is unclear who will benefit from screening. Mass screening is neither feasible nor cost-effective. The current literature suggests that persons in a family with two or more relatives with a history of SAH are most likely to benefit from screening. Individuals with a history of SAH, with aneurysms greater than 10 mm in diameter or with symptomatic aneurysms are clearly at increased risk for SAH. These aneurysms should be treated, though the method of treatment remains open to question. Treatment of older patients or those with smaller aneurysms has been modeled by decision analysis, but has yet to be verified in a prospective clinical trial. Future directions for aneurysm management are explored.

Unruptured intracranial aneurysms: a review

OBJECT

In this article, pathological, radiological, and clinical information regarding unruptured intracranial aneurysms is reviewed.

METHODS

Treatment decisions require that surgeons and interventionists take into account information obtained in pathological, radiological, and clinical studies of unruptured aneurysms. The author has performed a detailed review of the literature and has compared, contrasted, and summarized his findings. Unruptured aneurysms may be classified as truly incidental, part of a multiple aneurysm constellation, or symptomatic by virtue of their mass, irritative, or embolic effects. Unruptured aneurysms with clinical pathological profiles resembling those of ruptured lesions should be considered for treatment at a smaller size than unruptured lesions with profiles typical of intact aneurysms, as has been determined at autopsy in patients who have died of other causes. The track record of the surgeon or interventionist and the institution in which treatment is to be performed should be considered while debating treatment options. In cases in which treatment is not performed immediately, ongoing periodic radiological assessment may be wise. Radiological investigations to detect unruptured aneurysms in asymptomatic patients should be restricted to high-prevalence groups such as adults with a strong family history of aneurysms or patients with autosomal dominant polycystic kidney disease. All patients with intact lesions should be strongly advised to discontinue cigarette smoking if they are addicted.

CONCLUSIONS

The current state of knowledge about unruptured aneurysms does not support the use of the largest diameter of the lesion as the sole criterion on which to base treatment decisions, although it is of undoubted importance.

Endovascular treatment of unruptured aneurysms

BACKGROUND AND PURPOSE

We sought to better define the morbidity of endovascular Guglielmi detachable coil (GDC) treatment of unruptured cerebral aneurysms and to discuss its role in the prevention of subarachnoid hemorrhage.

METHODS

We conducted an observational study from August 1992 to June 1999 of 125 unruptured aneurysms treated with GDC in 116 patients: 91 women (78.4%) and 25 men (21.6%), aged 30 to 78 years (mean age, 50.6 years). Immediate and late clinical results were recorded for any neurological event or hemorrhage related to the treated unruptured aneurysm. Angiographic results are reported as immediate, early (2 to 12 months), intermediate (12 to 30 months), and late follow-up (>30 months).

RESULTS

Immediate angiographic results showed complete obliteration (class 1) in 59 (47.2%) or residual neck (class 2) in 53 aneurysms (42.4%), leaving 6 residual aneurysms (4.8%) and 7 failures (5.6%). Early follow-up angiograms, available in 100 treated aneurysms (84%), revealed class 1 in 52% and class 2 in 41%. Intermediate angiograms, available in 53 aneurysms (44.5%), showed class 1 in 47.2% and class 2 in 43.4%, while late results, available in 37 lesions (31.1%), had class 1 and 2 in 48.6% and 37.8%, respectively. Six patients suffered a permanent neurological deficit at last follow-up (5.2%), with a good outcome in 5 patients and fair outcome in 1 patient. There was no mortality. There was no aneurysmal rupture during a mean clinical follow-up of 32.1 months.

CONCLUSIONS

Endovascular treatment with GDC for unruptured aneurysms is relatively safe. Its role in the prevention of aneurysmal rupture remains to be determined, preferably by a randomized study.

Unruptured Intracranial Aneurysms: Appraisal of the Literature and Suggested Recommendations for Surgery, Using Evidence-based Medicine Criteria

OBJECTIVE

The literature on unruptured intracranial aneurysms is reviewed, and an attempt is made to stratify it according to the weight of the evidence. Recommendations for surgery are suggested, using evidence-based criteria.

METHODS

A MEDLINE search was performed for 1966 to 1999. The focus was restricted to surgical management rather than other types of management, such as endovascular treatments. Each article was classified as Class I, II, or III according to the weight of the evidence. Some articles, such as literature reviews and data analyses, did not fit this classification and were grouped separately. Recommendations are based on the evidence available.

RESULTS

Forty-five articles were reviewed. Thirteen articles contained information on the natural history, 19 contained data on the risks of surgery, and 2 contained information on both. In addition, 11 contained analyses of costs and benefits. None met the criteria for Class I evidence. Seven articles on the natural history and 7 on the risks of surgery met the criteria for Class II evidence, and 6 and 12, respectively, met those for Class III evidence. The remainder of the articles were analyses or review articles.

CONCLUSION

There is insufficient evidence to recommend a standard of management. As a therapeutic guideline, conservative treatment is recommended for small aneurysms (&lt;10 mm) and asymptomatic nongiant aneurysms in older people, whereas surgery is recommended for larger aneurysms in younger people and symptomatic aneurysms in fit patients. Other recommendations can be justified only as therapeutic options, using evidence-based criteria. Areas for future investigation are discussed.

Risk analysis of treatment of unruptured aneurysms

OBJECTIVES

To calculate the expected number of life-years saved by surgical treatment of unruptured intracranial aneurysms at ages over 20 years.

METHODS

An actuarial risk analysis of the treatment of unruptured intracranial aneurysms based on data from the International Study of Unruptured Intracranial Aneurysms (ISUIA). The benefits of operative treatment are calculated in terms of average life-years saved.

RESULTS

Results are presented as graphs of life-years saved or lost against age at the time of operative treatment for three groups of aneurysms: those under 10 mm in diameter with no history of subarachnoid haemorrhage (SAH) from another aneurysm, those under 10 mm in diameter and a history of previous SAH from a different aneurysm, and those over 10 mm in diameter. Life-years are lost at all ages in the group under 10 mm with no history of SAH. For the group under 10 mm with a history of SAH about 4 years are saved at age 20 declining to 0 at around age 50. For aneurysms 10 mm or more in diameter about 8 life-years are saved at age 20 declining to 0 at around 50.

CONCLUSIONS

Clipping of unruptured aneurysms under 10 mm in diameter with no history of subarachnoid haemorrhage is not justified on actuarial grounds. Intervention in other unruptured aneurysms produces benefits in life expectancy up to the age of 50. There may be subgroups of aneurysms in which larger benefits exist.

Elective neck clipping for unruptured aneurysms in elderly patients

BACKGROUND

With the recent advancements of neuroimaging techniques, the number of unruptured aneurysms diagnosed in elderly patients has increased. However, the surgical indications in this special subgroup have not been studied critically. The purposes of this study were to analyze the results of elective neck clipping surgery for unruptured aneurysms in the elderly and to elucidate the surgical indications.

METHODS

From 1985 to 1997, 96 patients, aged 70 years or older, with 103 unruptured cerebral aneurysms underwent elective neck clipping. There were 67 females and 29 males. Their ages ranged from 70 to 86, with a mean of 73.3 years. Seventy-five aneurysms were asymptomatic and 28 were symptomatic. The aneurysms were located on the internal carotid artery (46.6%), middle cerebral artery (35.9%), anterior cerebral artery (16.5%), and basilar artery (1.0%).

RESULTS

The surgical outcome was a good recovery in 75 patients (78.1%), mild deficits in 12 (12.5%), severe deficits in 4 (4.2%), and death in 5 (5.2%). Recovery from preoperative symptoms with improved quality of life was seen in 22 (78.6%) of the 28 symptomatic cases. Multiple regression analysis showed that increase in the size of aneurysms and location on the middle cerebral artery and internal carotid artery were significantly related to a poor outcome. The causes of the five deaths were hemorrhagic infarction, systemic infection, and myocardial infarction.

CONCLUSION

Surgery for elective neck clipping of unruptured aneurysms in the elderly should be considered in symptomatic patients with simple aneurysms that can be clipped without the use of temporary clips.

Surgical and endovascular treatment of unruptured cerebral aneurysms at university hospitals

OBJECTIVE

To compare complications of surgical clipping and coil embolization in the treatment of unruptured aneurysms.

BACKGROUND

Surgical clipping has been the preferred treatment for unruptured cerebral aneurysms but endovascular coil embolization is an increasingly employed alternative. No direct comparisons of the techniques are available to guide clinical decision making.

METHODS

We performed a cohort study of patients treated for unruptured cerebral aneurysms at 60 university hospitals from January 1994 through June 1997 using the University HealthSystem Consortium database. The database was validated by chart review from one of the participant universities. The main outcome measures were in-hospital mortality and adverse outcomes, defined as in-hospital deaths and discharges to nursing homes or rehabilitation hospitals.

RESULTS

The primary treatment modality was surgical in 2,357 cases and endovascular in 255 cases. Adverse outcomes were significantly more common in surgical cases (18.5%) compared to endovascular cases (10.6%) (p = 0.002), and the difference was not altered after adjusting for age, sex, race, transfer admissions, emergency room admissions, and year of treatment (odds ratio [OR] 2.1, 95% confidence interval [CI] 1.4 to 3.3; p = 0.001). In-hospital mortality was also increased in surgical cases (2.3% versus 0.4%; p = 0.039), but the difference was not significant in the multivariable model (OR 6.3, 95% CI 0.9 to 46.1; p = 0.07). Length of stay and hospital charges were significantly greater for surgical cases (p < 0.0001 for each), and these differences were not affected by risk adjustment.

CONCLUSION

Endovascular coil embolization resulted in fewer adverse outcomes than surgery for unruptured cerebral aneurysms treated at the university hospitals studied. Although these results should be seen as preliminary, the magnitude of difference and current predominance of surgery appear to justify a randomized trial.

Which unruptured cerebral aneurysms should be treated? A cost-utility analysis

OBJECTIVE

To determine which unruptured cerebral aneurysms should be treated considering the risks. benefits, and costs.

BACKGROUND

Asymptomatic unruptured cerebral aneurysms are commonly treated by surgical clipping or endovascular coil embolization to prevent subarachnoid hemorrhage (SAH).

METHODS

We performed a cost-utility analysis comparing surgical clipping and endovascular coil embolization with no treatment for unruptured aneurysms. Eight clinical scenarios were defined based on aneurysm size, symptoms, and history of SAH from a different aneurysm. Health outcomes of a hypothetical cohort of 50-year-old women were modeled over the projected lifetime of the cohort. Costs were assessed from the societal perspective. We compared net quality-adjusted life years (QALYs) and cost per QALY of each therapy to no treatment.

RESULTS

For an asymptomatic unruptured aneurysm less than 10 mm in diameter in patients with no history of SAH from a different aneurysm, both procedures resulted in a net loss in QALYs, and confidence intervals (CI) were not compatible with a benefit from treatment (clipping, loss of 1.6 QALY [95% CI 1.1 to 2.1]; coiling, loss of 0.6 QALY [95% CI 0.2 to 0.8]). For larger aneurysms (> or = 10 mm), those producing symptoms by compressing neighboring nerves and brain structures, or in patients with a history of SAH from a different aneurysm, treatment was cost-effective. Coiling appeared more effective and cost-effective than clipping but these differences depended on relatively uncertain model parameters.

CONCLUSIONS

Treatment of small, asymptomatic, unruptured cerebral aneurysms in patients without a history of SAH worsens clinical outcomes, and thus is neither effective nor cost-effective. For aneurysms that are > or = 10 mm or symptomatic, or in patients with a history of SAH, treatment appears to be cost-effective.

Should we screen for familial intracranial aneurysm?

BACKGROUND AND PURPOSE

The purpose of this study was to establish whether individuals with a family history of >/=2 first-degree relatives with intracranial aneurysm should be offered screening for aneurysm.

METHODS

We derived 3 theoretical models and calculated the outcomes of screening with magnetic resonance angiography (MRA) followed by digital subtraction angiography (DSA) if MRA was positive (model 1), screening with DSA alone (model 2), and not screening (model 3). Screening was repeated at intervals of 10 years, and aneurysms detected were treated surgically. We assumed a prevalence of aneurysm of 9.8% (95% CI, 8.9% to 10.6%) in the population screened, an annual rupture rate of asymptomatic aneurysm of 0.8% (95% CI, 0.4% to 1.5%), and a 75% chance of poor outcome from rupture. We assumed the sensitivity and specificity of MRA were each 90% and the risk of DSA was 0.1%. The risk of surgery was taken as 5.1%.

RESULTS

Screening 1000 individuals on 3 occasions with MRA and DSA or with DSA alone followed by surgery resulted in poor outcome in 14 and 18 individuals, respectively, over 30 years. Without screening, poor outcome occurred in 15 individuals over the same period of time.

CONCLUSIONS

Screening is not an effective way of reducing morbidity and mortality from ruptured intracranial aneurysm in individuals with a history of >/=2 affected first-degree relatives with ruptured intracranial aneurysm unless the expected incidence of asymptomatic aneurysm is considerably >10%.

Mortality and morbidity of surgery for unruptured intracranial aneurysms: a meta-analysis

BACKGROUND AND PURPOSE

Greater availability and improvement of neuroradiological techniques have resulted in more frequent detection of unruptured aneurysms. Because prognosis of subarachnoid hemorrhage is still poor, preventive surgery is increasingly considered as a therapeutic option. Elective surgery requires reliable data on its risks. Therefore, we performed a meta-analysis on the mortality and morbidity of surgery for unruptured intracranial aneurysms.

METHODS

Through Medline and additional searches by hand, we retrieved studies on clipping of unruptured (additional, symptomatic, or incidental) aneurysms published from 1966 through June 1996. Two authors independently extracted data. We used weighted linear regression for data analysis.

RESULTS

We included 61 studies that involved 2460 patients (57% female; mean age, 50 years) and at least 2568 unruptured aneurysms (27% >25 mm, 30% located in the posterior circulation). Mortality was 2.6% (95% confidence interval [CI], 2.0% to 3.3%). Permanent morbidity occurred in 10.9% (95% CI, 9.6% to 12.2%) of patients. Postoperative mortality was significantly lower in more recent years for nongiant aneurysms and aneurysms with an anterior location; the last 2 characteristics were also associated with a significantly lower morbidity.

CONCLUSIONS

In studies published between 1966 and 1996 on clipping of unruptured aneurysms, mortality was 2.6% and morbidity was 10.9%. In calculating the pros and cons of preventive surgery, these proportions should be taken into account.

Risk of harboring an unruptured intracranial aneurysm

BACKGROUND AND PURPOSE

The purpose of the present study was to calculate the prevalence and relative risk of unruptured incidental intracranial aneurysms (IAs) among families with IA case(s) compared with the general population in one geographically defined area in East Finland and to identify the risk group that could benefit most from screening for IAs. We compared these results with our earlier study results of familial IA (FIA) cases, with two or more known IA cases in the same family.

METHODS

The study groups were collected from the catchment area of the University Hospital of Kuopio in East Finland. The inclusion criteria were age 30 to 70 years and unruptured incidental IAs > or =3 mm. Patients with previous subarachnoid hemorrhage or in whom a ruptured IA was found to be the cause of death were excluded from all study groups. During routine forensic autopsies the circle of Willis was studied for IAs to estimate the number of IAs in the general population. In the families with one known IA case and in FIA families, MR angiography was used as a preliminary screening method for IAs, followed by intra-arterial angiography to verify suspected IAs. Study populations were age and sex adjusted for the statistical calculations.

RESULTS

The relative risk for IAs among first-degree relatives in FIA families was 4.2 (95% confidence interval, 2.2 to 8.0) and among first-degree relatives in families with only one affected family member was 1.8 (95% confidence interval, 0.7 to 4.8) compared with the general population in East Finland.

CONCLUSIONS

First-degree relatives in FIA families constitute a high-risk group for incidental IAs, and this group would benefit from screening studies for IAs. Screening for IAs in families with only one affected member or in the general population is not recommended.

Patients with polycystic kidney disease would benefit from routine magnetic resonance angiographic screening for intracerebral aneurysms: a decision analysis

Autosomal dominant polycystic kidney disease (ADPKD) is associated with increased prevalence of cerebral aneurysms and increased risk of subarachnoid hemorrhage. A decision analysis by Levey et al. in 1983 demonstrated that patients with ADPKD would not significantly benefit from routine arteriographic screening for cerebral aneurysms. We reexamined this conclusion in light of new clinical data and the introduction of magnetic resonance imaging (MRI) as a screening method. We compared an MRI screening strategy with a nonscreening strategy. The screening strategy specified MRI screening and then neurosurgical management of detected aneurysms. The nonscreening strategy specified cerebrovascular care only in the event of subarachnoid hemorrhage. The decision tree incorporated estimates derived from the clinical literature for the prevalence of asymptomatic aneurysms in patients with ADPKD (15%), the annual incidence of aneurysmal rupture (1.6%), the morbidity and mortality rates associated with subarachnoid hemorrhage (70 and 56%, respectively), the risk of transfemoral arteriography (0.2%), the sensitivity and specificity of MRI, the morbidity and mortality rates associated with surgical treatment of an unruptured aneurysm (4.1 and 1.0%, respectively), and the life expectancy of patients with ADPKD. The model predicted that the screening strategy would provide 1.0 additional year of life without neurological disability to a 20-year-old patient with ADPKD. A sensitivity analysis showed that the model was most sensitive to estimates of the prevalence of aneurysms in ADPKD, the annual incidence of rupture, and the morbidity and mortality rates associated with rupture. A financial analysis showed that a screening strategy is likely to cost less than a nonscreening strategy. The model predicts that an MRI screening strategy would increase the life expectancy of young patients with ADPKD and reduce the financial impact on society of ADPKD.