Natural history of unruptured intracranial aneurysms: probability of and risk factors for aneurysm rupture

OBJECT: The authors conducted a study to investigate the long-term natural history of unruptured intracranial aneurysms and the predictive risk factors determining subsequent rupture in a patient population in which surgical selection of cases was not performed. METHODS: One hundred forty-two patients with 181 unruptured aneurysms were followed from the 1950s until death or the occurrence of subarachnoid hemorrhage or until the years 1997 to 1998. The annual and cumulative incidence of aneurysm rupture as well as several potential risk factors predictive of rupture were studied using lifetable analyses and Cox's proportional hazards regression models including time-dependent covariates. The median follow-up time was 19.7 years (range 0.8-38.9 years). During 2575 person-years of follow up, there were 33 first-time episodes of hemorrhage from previously unruptured aneurysms, for an average annual incidence of 1.3%. In 17 patients, hemorrhage led to death. The cumulative rate of bleeding was 10.5% at 10 years, 23% at 20 years, and 30.3% at 30 years after diagnosis. The diameter of the unruptured aneurysm (relative risk [RR] 1.11 per mm in diameter, 95% confidence interval [CI] 1-1.23, p = 0.05) and patient age at diagnosis inversely (RR 0.97 per year, 95% CI 0.93-1, p = 0.05) were significant independent predictors for a subsequent aneurysm rupture after adjustment for sex, hypertension, and aneurysm group. Active smoking status at the time of diagnosis was a significant risk factor for aneurysm rupture (RR 1.46, 95% CI 1.04-2.06, p = 0.033) after adjustment for size of the aneurysm, patient age, sex, presence of hypertension, and aneurysm group. Active smoking status as a time-dependent covariate was an even more significant risk factor for aneurysm rupture (adjusted RR 3.04, 95% CI 1.21-7.66, p = 0.02). CONCLUSIONS: Cigarette smoking, size of the unruptured intracranial aneurysm, and age, inversely, are important factors determining risk for subsequent aneurysm rupture. The authors conclude that such unruptured aneurysms should be surgically treated regardless of their size and of a patient's smoking status, especially in young and middle-aged adults, if this is technically possible and if the patient's concurrent diseases are not contraindications. Cessation of smoking may also be a good alternative to surgery in older patients with small-sized aneurysms.     

Anatomical evaluation of intracranial aneurysm rupture risk in patients with multiple aneurysms

Neurosurgical Review - In patients with aneurysmal subarachnoid hemorrhage (aSAH) and multiple aneurysms, there is a need to objectively identify the ruptured aneurysm. Additionally, studying the...     

Natural history of giant intracranial aneurysms

The outcome of a consecutive series of 28 patients with giant aneurysm who had been followed without surgery from one month to 12 years after the diagnosis was made, are presented with reviewing their radiological and clinical features. Symptoms and signs were directly or indirectly attributable to the intracranial mass effect and nine patients (32%) presented subarachnoid hemorrhage. Subarachnoid hemorrhage was frequently associated with intraventricular or intracerebral hemorrhage, a poor clinical grading at admission and a high mortality. Subarachnoid hemorrhage was most often recorded from the giant aneurysm at the supraclinoid portion of the internal carotid artery and the vertebro-basilar artery, but the rupture from the intracavernous giant aneurysm, completely thrombosed giant aneurysm and the fusiform type of giant aneurysm was rare. The mortality rate in 28 cases for the above follow up period was 46% (13 in 28 cases) and major morbidity occurred in 11% (3 in 28 cases). The above outcome of non operated giant aneurysm cases may justify the surgical management of the giant aneurysm, but as the intracavernous giant aneurysm and thrombosed giant aneurysm are relatively harmless, surgical indication should be carefully decided, especially in the older patients.     

Estimated low risk of rupture of small-sized unruptured intracranial aneurysms (UIAs) in relation to intracranial aneurysms in patients with subarachnoid haemorrhage

Objective

International guidelines for the management of unruptured intracranial aneurysms (UIAs) recommend observation in aneurysms <10 mm due to the estimated low risk of rupture. The aim of our study was analyse the data of recently treated patients with ruptured cerebral aneurysms with the special focus on size and configuration in view of the frequency scale in a daily routine setting.

Methods

We reviewed the data of all patients with aneurysmal subarachnoid haemorrhage (SAH) during the last 24 months at our institution. Configuration and size of the aneurysms were measured. Clinical data were collected using the following classifications for analysis: Hunt and Hess (H&H), modified Rankin Scale (mRS) and Fisher classification.

Results

Data of 135 patients with aneurysmal SAH (98 women, 37 men; ratio 2.6:1) were analysed. Analysis showed that 19 aneurysms (14 %) were >10 mm (mean size, 19.2 mm) and 116 aneurysms (85.9 %) <10 mm (mean size, 6.2 mm). In total, 112 were categorised as berry-like configured aneurysms (n?=?113 <10 mm, n?=?3 >10 mm), 18 as multi-lobar (n?=?16 <10 mm, n?=?2 >10 mm) and 5 as fusiform (n?=?4 <10 mm, n?=?1, >10 mm).

Conclusion

Since the results of our study showed that the majority of the aneurysms are <10 mm (mean, 6.2 mm), it is justified to challenge the recommendations of the international guidelines in a daily routine setting. We believe that the published data are not convincing enough to play a guidance role in daily routine. Due to improving surgical and endovascular techniques with satisfying results and the high number of ruptured small aneurysms, we believe a change in attitude in management of small-sized aneurysms is needed. Further diagnostic models are needed to determine the risk of rupture of intracranial aneurysms properly to obtain adequate treatment for UIAs.     

Incidence and risk factors of postoperative headache after endovascular coil embolization of unruptured intracranial aneurysms

Background

Endovascular coil embolization for unruptured intracranial aneurysms (UIAs) has gained popularity because of its low morbidity and mortality in a short-term context. However, Headache is sometimes brought about or worsened after endovascular treatment, and this complaint may lead to perplexing situations, albeit infrequently. The aim of this study is to estimate the practical incidence and risk factors of postoperative headache in patients with endovascular embolization of UIAs.

Method

One hundred and thirty patients who underwent endovascular treatment of UIAs between March 2006 and May 2012 were enrolled according to inclusion criteria. From a retrospective chart review, the patients who had worsening or newly developed headache from postoperative day 1 to in-hospital stay were investigated for analyzing risk factors of post-embolization headache. Factors based on patients’ demographics, anatomical and radiological features of the lesions, treatment, utilized devices and outcome were investigated, and statistically verified.

Results

Headache occurred or was exacerbated in 32 patients (24.6 %). Of these, 30 patients showed improvement within days, but two patients with previous migraine history complained of intermittent headache over 3 months after the embolization. Univariate comparison between the headache group and the non-headache group showed that internal carotid artery (ICA) segment aneurysm, stent-assisted coiling, and no history of hypertension were associated with post-embolization headache (p?<?0.05). However, stent-assisted coiling and no history of hypertension were significantly associated with post-embolization headache in logistic regression analysis (p?<?0.05).

Conclusions

In the current study, stent-assisted coiling and no history of hypertension were important risk factors for headache in patients undergoing endovascular coil embolization for UIAs. Further investigations are still necessary to confirm the correlation of other factors which did not reach statistical significance in post-embolization headache in this limited study.     

Incidence of growth and rupture of unruptured intracranial aneurysms followed by serial MRA

Background

The natural history, including growth and rupture, of unruptured intracranial aneurysms (UIAs) remains unknown. Here, we present the results of serial magnetic resonance angiography (MRA) follow-up study in 111 patients with 136 UIAs.

Method

A total of 111 patients with 136 UIAs were followed annually over the past 12 years, using 1.5-Tesla MRA. Follow-up was ended when UIAs were treated surgically, or the patients died of subarachnoid hemorrhage or other causes. Various factors influencing aneurysm rupture or growth were examined statistically.

Results

Aneurysm rupture and growth occurred in six and 13 of the 111 patients, respectively. Annual rupture rate was 1.8 % per year and annual growth rate was 3.9 % per year. Aneurysm size was the sole factor influencing rupture(H.R. 1.214, 95 % CI, 1.078–1.368) and multiplicity was the sole factor influencing aneurysm growth (H.R. 5.174, 95 % CI 1.81–14.80).

Conclusions

Serial MRA study showed that the incidence of UIA growth was twice as high as that of UIA rupture. As four patients showed aneurysm rupture or growth within 1 year, further investigations are necessary to determine the optimum interval of radiological investigation and to identify which UIAs grow or rupture within a short time.     

Risks of surgery for unruptured intracranial aneurysms

A series is presented of 43 patients with multiple aneurysms and subarachnoid hemorrhage in whom a second operation was necessary in order to clip all the aneurysms. There was one surgical death due to coronary thrombosis and infarction which occurred 3 weeks after surgery, for a surgical mortality rate of 2.3%. One patient developed a permanent neurological deficit (hemiparesis and dysphasia). Thus, the surgical risks are smaller than the natural risk of bleeding and death from hemorrhage. Patients with any other serious illness increasing the surgical risk should not be subjected to an operation for an unruptured aneurysm; a second operation is indicated in all low-risk patients with multiple aneurysms or with incidentally identified aneurysms.     

支架辅助栓塞未破裂颅内动脉瘤术后颅内微缺血危险因素

目的分析支架辅助栓塞(SAE)治疗未破裂颅内动脉瘤后发生颅内微缺血(IMI)的危险因素。方法回顾性分析236例接受SAE治疗的未破裂颅内动脉瘤患者,根据术后3天内头部MR弥散加权成像(DWI)检查结果判断是否发生IMI;采用单因素分析和多因素Logistic回归分析筛选IMI危险因素。结果 236例中,97例(97/236, 41.10%)发生IMI(IMI组),139例未发生IMI(非IMI组,n=139)。2组间合并糖尿病、缺血性卒中病史、血小板抑制不足、前交通动脉瘤、伴瘤内附壁血栓、支架贴壁不良及微弹簧圈襻疝出瘤囊差异有统计学意义(P均0.05)。多因素Logistic回归分析结果显示,血小板抑制不足、前交通动脉瘤、伴瘤内附壁血栓、支架贴壁不良及微弹簧圈襻疝出瘤囊是IMI的独立危险因素(P均0.05)。结论 SAE治疗未破裂颅内动脉瘤后可发生IMI;血小板抑制不足、前交通动脉瘤、伴瘤内附壁血栓、支架贴壁不良及微弹簧圈襻疝出瘤囊促进IMI发生。     

Rupture of previously documented asymptomatic unruptured aneurysms--aneurysm size: risk factor for aneurysm rupture

The natural history of asymptomatic unruptured aneurysms is not clear. We conducted a follow up study of 100 patients (since 1993) with 122 asymptomatic unruptured aneurysms that had not been operated on. We report five patients with previously documented asymptomatic unruptured aneurysms smaller than 10 mm in diameter that subsequently ruptured. Among the 100 patients, five had suffered subarachnoid hemorrhage (SAH) due to rupturing of an aneurysm. Of the 5 cases, 1 was male and 4 were female, with ages ranging from 59-73 years (mean age, 68 years). The aneurysms were on the MCA in 3, on the BA-SCA in 1, on the IC-PC in 1. The maximal diameter of the aneurysms at diagnosis ranged from 4.5 to 8 mm. The period from discovery to SAH was from 4 to 69 months and the cumulative rate of rupture of the aneurysms was 1.5 percent per year. Four of the 5 cases increased in size after the rupture. In our series, 2 of the 5 cases showed enlargement and the development of an aneurysmal bleb in the follow up MRA and 3D-CTA. The present study demonstrates that five asymptomatic unruptured aneurysms less than 10 mm in diameter subsequently ruptured. We ought to seriously consider the assertion published in the New England Journal of Medicine (Dec. 10, 1998), that unruptured aneurysms less than 10 mm in diameter have a very low probability of subsequent rupture.     

Natural history of unruptured cerebral aneurysms of the unoperated and observed cases

PURPOSE: Natural history of unruptured cerebral aneurysms is still a matter of discussion. In this study, we investigated the prognosis of unruptured cerebral aneurysms of unoperated cases in a prospective design. METHODS: Between September, 1992 and December, 2001, we have encountered a 256 cases of unruptured cerebral aneurysms. Among them, 118 cases were observed and were checked every year for their status. The endpoint was designed as their death and aneurysm rupture. Their rupture rate, mortality due to aneurysm death, and the cause of death other than aneurysm were investigated. Univariate analysis, chi-square test was used as statistics. A p-value less than 0.05 was considered as significant. RESULTS: Annual rupture rate of unoperated unruptured cerebral aneurysms of size below 5 mm, between 5-15 mm, and over 15 mm increased according to the aneurysm size, 0.4%, 3.3% and 9.9% respectively. The sole risk factor for the feasibility of rupture of unruptured aneurysms was their size (p < 0.001). Aneurysm related mortality, however, was high in posterior circulation aneurysms. In patients under 70 years of age, 45% of patients died of cerebral aneurysms, but this rate decreased to 17% for patients over 70 years of age. CONCLUSION: The rupture rate of unruptured cerebral aneurysms over 5 mm in size is not low. Unruptured aneurysms of the posterior circulation may have a much higher risk of rupture, so further investigation is necessary.     

Risk perception of unruptured intracranial aneurysms

Object

Recent prospective studies have shown that the rupture rate of small unruptured intracranial aneurysms is very low. However, awareness of harboring an aneurysm often provokes anxiety and depression, which may reduce the quality of life (QOL).

Methods

This cross-sectional study enrolled 52 patients who had previously been notified of the presence of untreated unruptured aneurysms. A Markov model was constructed to simulate the natural history over time, and the age- and size-specific loss of quality-adjusted life year (QALY) caused by the aneurysms was calculated. Preference-based subjective QALY losses (P_SG and P_TTO) were assessed using the standard gamble (SG) and time trade-off (TTO) according to patient’s own perceptions.

Results

Calculated theoretical QALY losses were relatively small with median values of 0.4 years (interquartile range [IQR] 0.1–1.0 years) and 1.9 % (IQR 1.1–3.7 %) of expected lifetime. The median values of P_SG and P_TTO were 10.0 % (IQR 5.0–14.3 %) and 19.5 % (IQR 9.0–25.0 %), respectively. Although theoretical QALY losses were smaller in the patients with small aneurysms (<5 mm) than in patients with medium?～?large aneurysms (≥5 mm), the P_SG and P_TTO were almost the same in both groups. The discrepancy between theoretical and subjective QALY losses was prominent in patients with small aneurysms.

Conclusions

Notification of unruptured aneurysms exerts a significant psychological burden, and excessively reduces the QOL relative to the theoretical risks. The present study suggests that neurosurgeons should reconsider the method used to inform patients of small lesions with low risk of severe consequences.     

Risks of surgical treatment for unruptured intracranial aneurysms

The risks of surgical treatment for unruptured intracranial aneurysms, as well as the significance of evaluating cerebral blood flow (CBF), are here reported. Out of 72 patients who underwent unruptured aneurysm surgery without such complications as occlusion of the main trunk or perforating arteries, or brain contusion, and who according to CT scans, did not have new lesions related to the operations, 18 patients (25%) developed neurological deficits postoperatively. In 17 of these 18 patients, postoperative neurological deficits (frontal sign: 7, paresis: 4, and seizure: 6 cases) disappeared within 2 weeks following the operations. In the other patient, who was treated for subcortical hematoma in the left temporal lobe before aneurysm surgery, permanent speech disturbance appeared postoperatively. In the 18 patients with postoperative neurological deficits, the mean CBF value (36.2ml/100g/min) was statistically lower than that in the patients (46.2ml/100g/min) who had no postoperative neurological deficits (p less than 0.001). The rate of the patients with lower CBF values who developed postoperative neurological deficits, was statistically higher than that of patients with CBF values greater than 40ml/100g/min (p less than 0.002). In the patients with lower CBF values, common operative procedures for unruptured aneurysms such as craniotomy and mild brain retractions, may damage brain tissue. Careful perioperative management is needed for patients who undergo unruptured aneurysm surgery, because a lower CBF value may represent the degree of brain fragility.     

Screening of risk groups for discovering intracranial aneurysms before rupture

In development of intracranial aneurysms contribute genetic factors together with smoking, hypertension, diabetes mellitus. Epidemiology studies suggest that as many as 5% of people harbour a cerebral aneurysm by age 75. Rupture of cerebral aneurysm is the most frequent cause of spontaneous subarachnoid haemorrhage (up to 80%.) Annual incidence of SAH is 10-14/100 000, but only 15-20% of aneurysms will rupture, and that will happen probably between 40-60 years. The morbidity and mortality of aneurismal subarachnoid (SAH) continues to be high. It is not possible to predict who has aneurysm and is it going to bleed or not, but it is possible to reveal high risk groups (polycystic kidney disease, Ehlers-Danlos sy, Marphan sy, family history of cerebral aneurysms, suspect de novo aneurysm formation in patients with prior history of cerebral aneurysm). Reviewing data from literature and reporting cases from each group with high risk, that have been screened and aneurysms discovered, authors wish to focus interest on this matter and propose screening program for these groups of patients. The mortality and morbidity in cases treated before rupture is significantly lower than after SAH, so screening programs could save many lives. According to our preliminara data, mostly based on control angiographies after 8-10 zears in patients previouslz operated for intracranial aneurysmas, from 15 angipgraphies 4 revealed new aneurysms (26% in 10 years period) with total number of 6 de novo formed aneurysms, which is not valid due to small number of patients but strongly suggests the importancy of screening program for risk groups.     

Surgical treatment of unruptured intracranial aneurysms

Summary The author has reviewed a series of 19 patients with unruptured aneurysms treated surgically during a 5-year period from 1976 to 1981. Unruptured aneurysms found in patients with multiple aneurysms and subarachnoid haemorrhage due to ruptured aneurysms are not included in this series. Literature on this subject is reviewed. There was no mortality and results were excellent in 7 patients with asymptomatic aneurysms. In 12 patient with symptomatic aneurysms there was no mortality and results were good to excellent in 9 patients. In 2 the results were unsatisfactory.The series included aneurysms varying in size from 5 mm to over 2.5 cm (giant aneurysm). Controversial aspects of surgery of unruptured intracranial aneurysms are discussed. The authors recommend surgical treatment of unruptured intracranial aneurysms regardless of size until such time when more definitive information is available about the natural history of these lesions.