Recommendations for the management of patients with unruptured intracranial aneurysms: A Statement for healthcare professionals from the Stroke Council of the American Heart Association

Anévrismes intracrâniens non rompus : que proposer ?

Intracranial unruptured aneurysm (ICUA) has become a common condition for patient consultation. The mortality rate after fissuration is estimated to be between 52% and 85.7%. The final therapeutic decision results from a balance between the risk of rupture and risks related to the aneurysmal exclusion. Analysis of the risk of rupture risk enables a classification of risk factors. Depending on the circumstances of diagnosis, we considered the ICUA at high risk of rupture for incidental ICUA larger than 7 mm and in the event of associated aneurysms. Classifying by morphologic features, high-risk ICUA were located in the vertebrobasilar system (RR: 4.4; 95%CI: 2.7-6.8), those with a size between 7 and 12 mm (RR: 3.3; 95%CO: 1.3-8.2), larger than 12 mm (RR: 17; 95%CI: 8-36.1), those that were multilobular or a larger size and those ones with a index P/L superior to 3.4 (risk x20). Familial ICUA would expose to a major rupture risk (2 to 7 times sporadic ICUA). Some systemic factors were related to ICUA rupture: arterial hypertension (RR: 1.46; 95%CI: 1.01-2.11) and smoking addiction (RR: 3.04; 95%CI: 1.21-7.66). After microsurgical exclusion, the morbidity and mortality rates were 10% and 2% respectively. Some microsurgical morbidity factors were identified: age (32%>65 years), size (14%>15 mm), vertebrobasilar location and temporary occlusion. The rupture incidence after microsurgical exclusion was estimated 0.26%/year. After endovascular exclusion, the morbidity and mortality rates were 8% and 1% respectively. The complete exclusion rate varied between 47% and 67%. The rupture risk was estimated at 0.9%/year. Treatment recommendations were classified into 3 categories.

Inadequate website disclosure of surgical outcome of intracranial aneurysms

Social demand for the disclosure of medical information is increasing, especially the treatment for unruptured intracranial aneurysms. This study investigated to what extent information on the treatment for unruptured intracranial aneurysms is disclosed on websites in Japan. We surveyed 1225 institutions authorized by The Japan Neurosurgical Society. The following factors were analyzed: percentage of institutions with websites, disclosure of number of surgeries, and disclosure of outcome of treatment for ruptured and unruptured intracranial aneurysms. Of the 1225 institutions surveyed, 1097 (89.6%) had their own websites. The total number of websites was 1262 since some institutions have several homepages in different websites. The annual number of surgeries was shown in 274 of the 1225 institutions (22.4%). The outcome of treatment for ruptured intracranial aneurysms was disclosed in 104 of the 1225 institutions (8.5%). The outcome of treatment for unruptured intracranial aneurysms was shown in only 32 of the 1225 institutions (2.6%). Disclosure of outcome of treatment for unruptured intracranial aneurysms on websites is not common. To improve disclosure of the outcome on websites, guidelines should be established.

Neurological, neuropsychological, and functional outcome following treatment for unruptured intracranial aneurysms

The objective of this study was to carry out a detailed investigation of the neurological, neuropsychological, and return-to-work status of treatment for unruptured intracranial aneurysms (UIAs). A prospective design was used to evaluate the outcome of UIA treatment in a group of 26 UIA patients. Over a 24-month period UIA patients were assessed prior to treatment, during hospitalization, at three months and at six months following treatment. Their performance was compared to a group of 20 matched controls. Neurological morbidity as a result of the UIA treatment was 5%, as assessed by the Glasgow Outcome Scale (GOS) or Rankin at 3 months. The Telephone Interview for Cognitive Status (TICS) proved to be unreliable as a measure of cognitive change. Reliability of change analysis was more sensitive than group analysis, and revealed a pattern of cognitive deficits in 10% of patients as a result of the UIA treatment. In addition, 25% of patients reported a change in work role as a result of the UIA treatment. While 10% of patients sustained mild to moderate neurological and cognitive impairments 3 to 6 months following UIA treatment, their deficits were not as wide-ranging nor as severe as those sustained by patients who survive a subarachnoid hemorrhage (SAH).

Management of ruptured aneurysms combined with coexisting aneurysms

In patients suffering from subarachnoid haemorrhage (SAH) and presenting with multiple intracranial aneurysms (MIA) two questions have to be decided on: 1st when is the ideal moment to eliminate the ruptured aneurysm and 2nd when to treat the coexisting aneurysms. In our series we retrospectively analysed 124 SAH-patients presenting with a total of 323 aneurysms. In 57 patients the ruptured aneurysm and all coexisting aneurysms were clipped during the first operation, whereas in 9 patients only some of the coexisting aneurysms (group-A; age in median 55 years) were clipped besides the ruptured one. In 55 patients (group-B; age in median 55 years) the first operation was restricted to clipping the ruptured aneurysm, dealing with the coexisting aneurysm subsequently. Immediately after admission 3 patients passed away. One of the 64 patients waiting (average 60 days, median 14 days) for the subsequent clipping of the not yet secured aneurysms suffered a SAH. Six to 12 months after the initial SAH, 78% of the cases in both groups reached a Glasgow Outcome Score of 4 or 5. Even if in patients with coexisting unruptured intracranial aneurysms the elimination of each and every aneurysm is recommended, the advantages of an unstaged procedure versus the additional strain caused by the prolongation of the procedure, e.g. approach over the midline, 2 or more craniotomies, and the risk of additional ischemic damage to the brain, caused by increased manipulation of cerebral arteries and brain tissue, have to be carefully considered. This is of special importance in dealing with patients in higher Hunt and Hess grades.

Complications and postoperative care in patients undergoing treatment for unruptured intracranial aneurysms

Endovascular treatment has become a feasible alternative in the management of aneurysmal subarachnoid hemorrhage. After endovascular or surgical treatment of patients with unruptured intracranial aneurysms (UIAs), little is known about the practices of observation or need for intensive care. We analyzed retrospectively perioperative complications that were associated with the procedure and postoperative care in patients undergoing management of UIAs. A total of 53 patients underwent endovascular treatment and 105 patients surgical treatment. Location of the aneurysm was the main determinant of the modality of treatment. In the endovascular group, 34 patients were conscious during the procedure and 19 were under general anesthesia. Six patients in the endovascular and 9 in the surgical group experienced complications during the procedure. After the procedure, complications were more common in the surgical group than in the endovascular group (11 versus 0 patients, P = 0.015). Six of the postoperative complications of surgically treated patients occurred in the intensive care unit. Two patients in the endovascular group and five in the surgical group had major neurologic deficits as a consequence of complications. One surgically treated patient died. Both endovascular and surgical treatment of UIAs carry risks that may result in severe neurologic impairment. Patients should be observed with equal vigilance with either treatment option. Surgical treatment is associated with emergencies that require prompt interventions postoperatively and therefore close observation in an ICU setting may be preferable in patients who have undergone surgical treatment of UIAs. Complications after uneventful endovascular procedures seem to be rare.

Unruptured intracranial aneurysms treated by three-dimensional coil embolization: evaluation of the postoperative aneurysm occlusion volume

Our purpose was to evaluate the postoperative aneurysm occlusion volume and clinical results of treating unruptured intracranial aneurysm using three-dimensional (3D) coils. Over a 2-year period 62 aneurysms (39 with a neck < or =4 mm, 23 with a neck >4 mm) in 62 patients in five participating centres were treated. The procedure consisted, firstly, of framing the aneurysm with one or more spherical 3D coils, and secondly, of filling it with two-dimensional (2D) helical coils. Anatomical and clinical results were evaluated by univariate analysis. Multivariate analysis was used to identify independent predictors of these results. For neck sizes < or =4 and >4 mm, angiographic occlusion was complete in 31 (79%) and 16 (70%) aneurysms, respectively; the mean percentage of occlusion volume was 31.4% and 29.5%, respectively, and postoperative morbidity was 3% and 4%, respectively, with no significant differences between the two groups. There were no deaths. However, occlusion volume correlated with sac size (P = 0.037) and sac-to-neck ratio <1.5 (P = 0.073), except when three or more 3D coils per aneurysm were used (P = 0.516 and P = 0.308, respectively). Occlusion volume correlated with the number of 3D coils per aneurysm (P < 0.001) and was an independent predictor of angiographic complete occlusion (P = 0.002). The use of the largest number of 3D coils per aneurysm was safe and may improve the postoperative volume and angiographic occlusion of aneurysms with a neck >4 mm, provided the sac-to-neck ratio is > or =1.5.

The presence of tandem endothelial nitric oxide synthase gene polymorphisms identifying brain aneurysms more prone to rupture

Object. It is becoming apparent that the presence of certain genetic variations (polymorphisms) may increase the individual's susceptibility to cardiovascular diseases, even in the absence of a family history. We hypothesized that brain aneurysms more prone to rupture may be identified on the basis of an individual's genotype for endothelial nitric oxide synthase (eNOS), a critical vasomodulatory protein found to be increasingly relevant to the pathobiology of aneurysms.

Methods. Patients' clinical data were recorded prospectively. Genomic DNA was isolated from blood samples obtained from individuals presenting consecutively to the Mayo Clinic with ruptured (58 patients) or unruptured (49 patients) intracranial saccular aneurysms. Using polymerase chain reaction and gene microarray technology, the following eNOS genetic polymorphisms were studied: intron-4 27—base pair variable number of tandem repeats (27 VNTR); promoter single nucleotide polymorphism (T-786C SNP); and exon-7 SNP (G894T SNP).

Both groups of patients had similar demographic and clinical characteristics. For all three polymorphisms, variant alleles (p ≤ 0.003) and their corresponding genotypes (p ≤ 0.006) were found two to four times more frequently in patients with ruptured aneurysms than in patients with unruptured aneurysms. Strikingly, the odds ratio for presenting with a ruptured brain aneurysm among individuals demonstrating the copresence of all three variant alleles was 11.4 (95% confidence interval 1.7–75.9, p = 0.004).

Conclusions. The authors have uniquely identified a set of tandem eNOS gene variations whose presence can be used to identify patients with aneurysms likely to rupture. We believe that if this finding is reproducible in a large multicenter study, in addition to known anatomical factors a rapid and cost-effective screening tool will become available to clinicians as a genetic aid to predict the risks of rupture in patients presenting with unruptured intracranial aneurysms.

Fourier analysis of intracranial aneurysms: towards an objective and quantitative evaluation of the shape of aneurysms

Shape irregularities of intracranial aneurysms may indicate an increased risk of rupture. To quantify morphological differences, Fourier analysis of the shape of intracranial aneurysms was introduced. We compared the morphology of 45 unruptured (UIA) and 46 ruptured intracranial aneurysms (RIA) in 70 consecutive patients on the basis of 3D-rotational angiography. Fourier analysis, coefficient of roundness and qualitative shape assessment were determined for each aneurysm. Morphometric analysis revealed significantly smaller coefficient of roundness (P < 0.02) and higher values for Fourier amplitudes numbers 2, 3 and 7 (P < 0.01) in the RIA group, indicating more complex and irregular morphology in RIA. Qualitative assessment from 3D-reconstructions showed surface irregularities in 78% of RIA and 42% of UIA (P < 0.05). Our data have shown significant differences in shape between RIA and UIA, and further developments of Fourier analysis may provide an objective factor for the assessment of the risk of rupture.

Endovascular treatment of unruptured cerebral aneurysms

76 consecutive patients with 78 unruptured cerebral aneurysms underwent endovascular therapy from July 1999 to May 2004 in our institute. For the wide-necked aneurysms, the remodeling technique, double microcatheter technique, or stent-assisted coil embolization was used, while a parent artery occlusion or covered stent was applied for the giant or fusiform aneurysms. Immediate angiographical results demonstrated 33 complete occlusions, 26 neck remnants, and 14 dome fillings. Four cases were treated with parent occlusion or stenting only, and one case was not treated with embolization but with clipping due to the rupture of the aneurysm during coil embolization. Immediate angiographic findings demonstrated that in aneurysms between 5 to 10 mm, the rate of complete occlusion was 48%, that of neck remnants 33%, and that of dome fillings 27%. In aneurysms between 11 to 25 mm, the rate of complete occlusion was 14%, that of neck remnants 28%, and that of dome fillings was 58%. In the angiographic follow-up results, all aneurysms smaller than 5 mm showed complete occlusion. In aneurysms between 5 to 10 mm, 74% of the aneurysms showed complete occlusion, and 21% showed neck remnants, and 5% showed dome filling. In aneurysms between 10 to 24 mm, 25% showed complete occlusion, while 75% showed dome filling. The overall mortality rate was 0% and the morbidity rate was 3.7% (2 major strokes, 1 minor stroke) at 30-days after embolization. In the clinical follow-up study, one case of a large basilar tip aneurysm caused a fatal rupture 28 months after the initial embolization. Endovascular therapy was performed on the unruptured aneurysms and was found to be an acceptable treatment, except for durability in cases of large aneurysms.

Management of unruptured cerebral aneurysms in patients with polycystic kidney disease

BACKGROUND

Autosomal dominant polycystic kidney disease (PKD) is a hereditary disorder characterized by bilateral multiple renal cysts and early onset chronic renal failure. PKD patients tend to suffer their subarachnoid hemorrhage at a younger age. Unruptured aneurysms in PKD patients are not always innocuous, and proactive treatment has been indicated for these lesions. However, the management of PKD patients undergoing unruptured cerebral aneurysm surgery has been documented on only a few occasions. The purpose of this study was to better define the management of unruptured cerebral aneurysms in patients with PKD.

METHODS

We present a retrospective review of the management of unruptured cerebral aneurysms in 16 patients with PKD. Eight patients were maintained through chronic hemodialysis whereas the remaining 8 patients did not require hemodialysis, at the time of treatment of their cerebral aneurysms. The mean follow-up period was 24 months.

RESULTS

In the nonhemodialysis patients prophylactic hemodialysis was routinely performed after cerebral angiography to prevent deterioration of the pre-existing renal dysfunction. Microsurgical clipping of the aneurysm was performed in 15 patients (7 nonhemodialysis and 8 hemodialysis patients) and intravascular coil embolization was performed in 1 nonhemodialysis patient. One nonhemodialysis patient who underwent microsurgical clipping required a temporary hemodialysis after surgery, but the patient was not shifted to chronic hemodialysis. No patients developed postprocedural complications, and each showed an excellent recovery.

CONCLUSION

PKD patients with unruptured cerebral aneurysms can be safely treated with an appropriate treatment strategy including the use of prophylactic hemodialysis.

Strategies of neuroprotection for intracranial aneurysms

Neuroprotection for patients with intracranial aneurysms encompasses the preservation of brain cells endangered by a limited blood and oxygen supply due to aneurysm rupture, clipping or coiling, as well as vasospasm. A large variety of prophylactic and therapeutic neuroprotective strategies have been proposed, but success in human disease is quite limited. Topics of this chapter are the pathophysiology and treatment options of aneurysms, as well as promising neuroprotective strategies in further developmental stages: both physiologically based (hyperoxygenation, hypothermia, avoidance of hyperthermia and hyperglycaemia, hypertension, haemodilution and hypervolaemia) and pharmacologically based (antifibrinolytic drugs, calcium antagonists, anaesthetics, magnesium, erythropoietin and others). New concepts are ischaemic preconditioning, growth factors, and gene therapy. Each strategy is rated on underlying evidence, and research agendas are mentioned.

Pathogenesis, natural history, and treatment of unruptured intracranial aneurysms

Unruptured intracranial aneurysms (UIAs) are a major public health issue. These lesions have become increasingly recognized in recent years with the advent of advanced cerebral imaging techniques. Epidemiological evidence from multiple sources suggests that most intracranial aneurysms do not rupture. Therefore, it is desirable to identify which UIAs are at greatest risk of rupture when considering which to repair. It is important to compare size-, site-, and group-specific natural history rates with size-, site-, and age-specific morbidity and mortality associated with UIA repair because increased natural history risk often is associated with increased risk of aneurysm repair. Patient age is crucial in decision making because of its major effect on operative morbidity and mortality; however, it does not substantially affect natural history. The effect of age is most notable in patients about 50 years of age and older for open surgery and about 70 years of age and older for endovascular procedures. In general, rupture risk is lowest for patients in asymptomatic group 1 (no history of subarachnoid hemorrhage) with UIAs less than 7 mm in diameter in the anterior circulation. Surgical morbidity and mortality are most favorable for asymptomatic patients younger than 50 years who have UIAs less than 24 mm in diameter in the anterior circulation and no history of ischemic cerebrovascular disease. Endovascular morbidity and mortality may be less age dependent, and this could favor endovascular procedures, particularly in patients aged 50 to 70 years. An important issue is determining immediate vs long-term risk regarding treatment effectiveness and durability. This issue emphasizes the importance of long-term follow-up in patients after surgical and endovascular procedures.

Natural history and general management of unruptured intracranial aneurysms

After an aneurysmal subarachnoid hemorrhage, nearly half of the patients die and the half who survive suffer from irreversible cerebral damage. With increasing use of noninvasive neuroimaging techniques (for example, magnetic resonance and computerized tomography angiography), more unruptured cerebral aneurysms are found. To understand the prevalence of unruptured aneurysms in the general population, along with the risks of aneurysm formation, data on growth and rupture rates are crucial. The risk of rupture in aneurysms smaller than 10 mm is still not quite clear without a population-based prospective study. Nevertheless, a 0.5 to 2% annual risk may be a reasonable estimate. Growing aneurysms and those larger than 10 mm carry a higher rate of rupture. The management of an unruptured intracranial aneurysm should be based on a thorough understanding of the natural history of these lesions and careful evaluation of the morbidity and mortality levels associated with each treatment option.

Update on genetic evidence for rupture-prone compared with rupture-resistant intracranial saccular aneurysms

Object

Anecdotal evidence exists for at least two subpopulations of intracranial saccular aneurysms; those that form rapidly and rupture when small and those that enlarge slowly and are particularly prone to rupture when they are 10 mm or more in diameter. The goal in this study was to determine if there was genetic evidence to support the classification of intracranial saccular aneurysms as “rupture-prone” or “rupture-resistant” lesions.

Methods

The authors prospectively obtained and analyzed clinical and genetic data in a cohort of 197 individuals composed of 58 patients with ruptured intracranial saccular aneurysms, 49 with unruptured aneurysms, and 90 healthy community volunteers. Based on recent studies supporting an increasingly relevant role for the critical vasomodulatory protein endothelial nitric oxide synthase (eNOS) in aneurysm pathobiology, the authors assayed blood from all 197 participants to determine and compare their eNOS genotypes.

TheeNOSgene intron 4 27–base pair variable-number tandem-repeat polymorphism was significantly overrepre-sented in persons with ruptured intracranial saccular aneurysms compared with community volunteers (p <0.002). When comparing eNOS genotypes among patients with ruptured or unruptured aneurysms, an approximately 10-fold increase in the odds of presenting with brain aneurysm rupture was found among individuals with multiple variant eNOS alleles (p = 0.004).

Conclusions

Uniquely, the authors have identified a set ofeNOSgene variations whose presence indicates patients with intracranial saccular aneurysms that are more prone to rupture. The authors conclude that if these findings are reproducible in the setting of a large multicenter study, then in addition to known anatomical factors, a rapid and cost-effective genetic screening tool will become available to clinicians as an aid to predicting rupture risks in patients presenting with unruptured intracranial aneurysms.

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.

Anatomical and clinical outcomes after endovascular treatment for unruptured cerebral aneurysms. A single-center experience

SUMMARY

To describe the immediate and follow-up anatomical outcomes as well as procedure-related morbidity after endovascular procedures for unruptured cerebral aneurysms, we reviewed 68 patients with 78 unruptured aneurysms treated with detachable coils from may 1996 to february 2002. Angiograms were retrospectively reviewed for the nature of the aneurysms and the degree of therapeutic obliteration. Periprocedural complications, immediate clinical outcome and longterm neurological status were analyzed. Immediate anatomical outcomes were complete in 35 aneurysms (45%); residual neck in 24 (31%), partial contrast filling in 17 (22%), and failed embolization in two (2%). Of 27 aneurysms with follow-up angiography, 12 of the 13 aneurysms that were completely occluded in the initial treatment were still completely occluded at the end of a mean follow-up period of 17 months. Periprocedural complications were thromboembolic (n=6), haemorrhagic (n=3), coil protrusion (n=7) and other unrelated complications (n=3). Only two patients, with thromboembolic complications were moderately disabled with permanent neurological deficits in immediate clinical outcome, and their condition improved to independent in 1.5 and three months each. Small aneurysms and posterior circulation location showed more protective immediate results than aneurysms of large and anterior circulation after endovascular treatment (p values: 0.01 and 0.02). Our experiences of endovascular treatment for unruptured cerebral aneurysms were comparable to the results of recent series. Endovascular treatment for small posteriorly located aneurysms produced significantly better results than for large anteriorly located lesions.

Anxiety before and after surgical repair in patients with asymptomatic unruptured intracranial aneurysm

BACKGROUND

Ruptured intracranial aneurysm is a serious condition with high mortality and morbidity. Patients notified of the presence of the unruptured intracranial aneurysm may become anxious because of the fear of rupture. We prospectively investigated the anxiety of patients with unruptured intracranial aneurysm before and after surgery.

METHODS

Thirty-seven patients with an asymptomatic unruptured intracranial aneurysm were enrolled, 13 men and 24 women aged 32 to 70 years (mean age, 57.2 years), who underwent surgical repair of the aneurysm. The anxiety of patients was assessed one month before and after surgery using the Japanese version of the State-Trait Anxiety Inventory.

RESULTS

The trait anxiety scores, which refer to stable personality factors reflecting the general level of fearfulness, did not change significantly after surgery. In contrast, the state anxiety scores, which refer to transient anxiety that varies according to the situation, decreased significantly after surgery (p = 0.001, paired t test). Only the preoperative high state anxiety scores among the multiple variables were associated with the significant decrease in state anxiety after surgery (p = 0.0183, logistic regression analysis).

CONCLUSIONS

The anxiety of patients with asymptomatic unruptured intracranial aneurysm significantly decreased after surgery. Anxiety of patients with asymptomatic unruptured intracranial aneurysm may deserve attention in deciding whether to treat the aneurysm.

Endovascular coil occlusion of 1811 intracranial aneurysms: early angiographic and clinical results

OBJECTIVE

We sought to evaluate the early angiographic and clinical outcomes of the first session of endovascular coil occlusion of a large number of patients with intracranial aneurysms treated by five neurointerventionalists during a decade at a single center.

METHODS

We performed retrospective analyses of pre- and postprocedural angiographic studies and early clinical outcomes. Enrolled patients underwent endovascular treatment of intracranial aneurysms with detachable coils.

RESULTS

A total of 1811 aneurysms in 1579 patients were treated with coil occlusion. Of these, 90 to 100% occlusion of 86.5% of the aneurysms was achieved. In 82.3% of the procedures, no complications occurred. The clinical outcome profile at primary discharge according to the Glasgow Outcome Scale was as follows: Grade V, 74.6%; Grade IV, 6.7%; Grade III, 11.1%; Grade II, 3.1%; and Grade I, 4.5%. In patients with large aneurysms with wide necks, a lower occlusion rate and an increased complication rate were encountered. The use of three-dimensional and fibered coils resulted in higher occlusion rates. Balloon remodeling and stent deployment increased the complication rate. Previous aneurysm rupture, procedural complications, and vasospasm correlated with poor outcome. Of the patients in poor grade after aneurysm rupture, 42% recovered to Glasgow Outcome Scale Grade IV or V, as opposed to 90% of patients who were treated for unruptured aneurysms. The ischemic complication rate was 9%, and the hemorrhagic complication rate was 3%. The early procedural morbidity rate was 5.3%, and the procedural mortality rate was 1.5%. The management mortality rate was 4.4%.

CONCLUSION

These data confirm the safety and efficacy of endovascular coil occlusion for patients with intracranial aneurysms.

Neurological, neuropsychological, and psychosocial outcome following treatment of unruptured intracranial aneurysms: a review and commentary

Thirty studies published between 1977 and 2001 that focus on outcome following unruptured intracranial aneurysm (UIA) treatment are reviewed. Although findings from these studies suggest outcome from UIA treatment is reasonably good (between 5% and 25% morbidity and between 0-7% mortality), many of the complex issues associated with the treatment of UIAs remain controversial. Most of the studies reviewed address outcome in terms of mortality and neurological morbidity. Very few studies exist which include measures of outcome such as cognitive status, psychosocial functioning and quality of life. Given that patients facing treatment tend to be healthy middle-aged adults with many years of active working and social life ahead of them, it is important to take into account the long-term consequences of either harboring an UIA, or having it treated. The small number of studies that include cognitive, psychosocial and quality of life outcomes are reviewed in some detail and suggestions made for improving future UIA outcome research.

Endovascular Treatment of Asymptomatic Cerebral Aneurysms: Anatomic and Technical Factors Related to Ischemic Events and Coil Stabilization

The present study assessed the safety and efficacy of embolization using Guglielmi detachable coils (GDCs) in 100 asymptomatic cerebral aneurysms classified as sidewall (70) or terminal (30) aneurysms according to the parent artery (68 small aneurysms with a small neck, 21 small aneurysms with a wide neck, and 11 large aneurysms). A balloon-assisted technique was used in 49 aneurysms. Immediate angiography revealed that 71 aneurysms were completely obliterated. Transient deficits occurred in 19 patients, permanent deficits in four patients, and one patient died. Most complications occurred during or immediately after treatment and resolved within a few minutes to a few weeks. None of the surviving patients manifested significant morbidity at 1-year follow up. Follow-up angiographic study was performed in 79 aneurysms. Rates of recanalization and progressive thrombosis (total occlusion of the residual aneurysm at follow up) were 11% and 38%, respectively, in sidewall aneurysms, and 26% and 0%, respectively, in terminal aneurysms. Treatment with GDCs was effective for patients with small aneurysms with small necks, the morbidity was acceptable, and progressive thrombosis occurred during the follow-up period. GDC treatment achieved unsatisfactory results in patients with small terminal aneurysms with wide necks and in large aneurysms, because the obliteration rate was low, and the recanalization and complication rates were high. Multivariate analysis showed that complete occlusion was associated with small-necked aneurysms, and ischemic events tended to occur in terminal aneurysms and in aneurysms treated by the balloon-assisted technique.

Investigation of the surgically treated and untreated unruptured cerebral aneurysms of the anterior circulation

BACKGROUND

The natural history of unruptured cerebral aneurysms and the surgical risks are modified by several factors including size, location, and presence of subarachnoid hemorrhage (SAH). The main confusion arises because the backgrounds of the past reports describing the natural history or the surgical complication of unruptured cerebral aneurysms were different. The present study aimed to adjust the backgrounds and investigate the surgical indication with close monitoring of both surgically treated and untreated unruptured cerebral aneurysms.

METHODS

In the past 9 years, 201 patients who had unruptured anterior circulation aneurysms were monitored. The decision of the operation was not randomized. The patients were divided into three subgroups by the size of the aneurysms (small group: below 5 mm, medium group: between 5 and 15 mm, large group: over 15 mm). In both surgically untreated and treated patients, overall mortality and morbidity corresponding to Rankin score II or worse was counted as unruptured aneurysm related event. The ratio of event free was compared between surgically treated and untreated patients using Log-rank test.

RESULTS

In untreated patients, SAH was noted in 1 in the small group and 4 in the medium group. The annual rupture rate of the medium group was 12 times higher than that of the small group. In surgically treated patients, overall mortality and morbidity of the surgery was 2.3% in the small group, 3.6% in the medium group, and 20% in the large group. One surgically treated patient had SAH because of regrowth of aneurysm. When ratio of event free was compared, no significant advantage of surgery was noted in the small group and in all of the patients. However, the benefit of surgery was significant in the medium group (Log-rank p = 0.0189).

CONCLUSIONS

The present results indicated that prophylactic surgery has a benefit for the medium-size aneurysms (5-15 mm) of the anterior circulation. For large aneurysms, individual investigation is necessary because of the variety of surgical difficulties, and the complex symptoms because of rupture and the mass effect as well as cerebral embolism. In small aneurysms, careful observation may be a reasonable choice unless the aneurysm is at a specially high risk of rupture.

Intraoperative Cerebral Angiography: Superficial Temporal Artery Method and Results

OBJECTIVE

To report the method for and results of intraoperative cerebral angiography performed via the superficial temporal artery, for assessment of cerebral aneurysm surgery.

METHODS

All patients undergoing craniotomies for treatment of intracranial aneurysms were prospectively entered into a database. A policy of performing angiography via the superficial temporal artery in appropriate cases was instituted. This procedure was performed with retrograde catheterization of the superficial temporal artery, as it coursed over the zygomatic arch, with an 18-gauge, 1.88-inch, intravenous catheter and hand injection of contrast material, with intraoperative digital subtraction fluoroscopic guidance.

RESULTS

Thirty-six patients who underwent 38 craniotomies for clipping of 43 aneurysms underwent intraoperative angiography via the superficial temporal artery. There were six unexpected findings (14%), including four unexpected arterial occlusions and two unexpected residual aneurysms. One aneurysm was observed to be patent when it was punctured, after intraoperative angiography had indicated no filling of the aneurysm. Additional clips were placed. Three patients (8%) developed multiple arterial infarctions in the territory of the injected carotid artery, for which multiple causes were possible. Adequate angiographic images could usually be obtained with this method.

CONCLUSION

Intraoperative angiography via the superficial temporal artery is simple and is not associated with substantial complications. It is a reasonable alternative to transfemoral angiography for detection of adverse consequences of intracranial aneurysm clipping.

Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment

BACKGROUND

The management of unruptured intracranial aneurysms is controversial. Investigators from the International Study of Unruptured Intracranial Aneurysms aimed to assess the natural history of unruptured intracranial aneurysms and to measure the risk associated with their repair.

METHODS

Centres in the USA, Canada, and Europe enrolled patients for prospective assessment of unruptured aneurysms. Investigators recorded the natural history in patients who did not have surgery, and assessed morbidity and mortality associated with repair of unruptured aneurysms by either open surgery or endovascular procedures.

FINDINGS

4060 patients were assessed-1692 did not have aneurysmal repair, 1917 had open surgery, and 451 had endovascular procedures. 5-year cumulative rupture rates for patients who did not have a history of subarachnoid haemorrhage with aneurysms located in internal carotid artery, anterior communicating or anterior cerebral artery, or middle cerebral artery were 0%, 2. 6%, 14 5%, and 40% for aneurysms less than 7 mm, 7-12 mm, 13-24 mm, and 25 mm or greater, respectively, compared with rates of 2 5%, 14 5%, 18 4%, and 50%, respectively, for the same size categories involving posterior circulation and posterior communicating artery aneurysms. These rates were often equalled or exceeded by the risks associated with surgical or endovascular repair of comparable lesions. Patients' age was a strong predictor of surgical outcome, and the size and location of an aneurysm predict both surgical and endovascular outcomes.

INTERPRETATION

Many factors are involved in management of patients with unruptured intracranial aneurysms. Site, size, and group specific risks of the natural history should be compared with site, size, and age-specific risks of repair for each patient.

In-hospital Mortality and Morbidity after Surgical Treatment of Unruptured Intracranial Aneurysms in the United States, 1996–2000: The Effect of Hospital and Surgeon Volume

OBJECTIVE

We sought to determine the risk of adverse outcome after contemporary surgical treatment of patients with unruptured intracranial aneurysms in the United States. Patient, surgeon, and hospital characteristics were tested as potential outcome predictors, with particular attention to the surgeon's and hospital's volume of care.

METHODS

We performed a retrospective cohort study with the Nationwide Inpatient Sample, 1996 to 2000. Multivariate logistic and ordinal regression analyses were performed with endpoints of mortality, discharge other than to home, length of stay, and total hospital charges.

RESULTS

We identified 3498 patients who were treated at 463 hospitals, and we identified 585 surgeons in the database. Of all patients, 2.1% died, 3.3% were discharged to skilled-nursing facilities, and 12.8% were discharged to other facilities. The analysis adjusted for age, sex, race, primary payer, four variables measuring acuity of treatment and medical comorbidity, and five variables indicating symptoms and signs. The statistics for median annual number of unruptured aneurysms treated were eight per hospital and three per surgeon. High-volume hospitals had fewer adverse outcomes than hospitals that handled comparatively fewer unruptured aneurysms: discharge other than to home occurred after 15.6% of operations at high-volume hospitals (20 or more cases/yr) compared with 23.8% at low-volume hospitals (fewer than 4 cases/yr) (P = 0.002). High surgeon volume had a similar effect (15.3 versus 20.6%, P = 0.004). Mortality was lower at high-volume hospitals (1.6 versus 2.2%) than at hospitals that handled comparatively fewer unruptured aneurysms, but not significantly so. Patients treated by high-volume surgeons had fewer postoperative neurological complications (P = 0.04). Length of stay was not related to hospital volume. Charges were slightly higher at high-volume hospitals, partly because arteriography was performed more frequently than at hospitals that handled comparatively fewer unruptured aneurysms.

CONCLUSION

For patients with unruptured aneurysms who were treated in the United States between 1996 and 2000, surgery performed at high-volume institutions or by high-volume surgeons was associated with significantly lower morbidity and modestly lower mortality.

Unruptured intracranial aneurysms in patients with transient cerebral ischemic episodes. Optional managements and literature review

Clinical experience about the management of patients with an unruptured intracranial aneurysm (UIA) presenting transient cerebral ischemic attacks (TIAs) is usually restricted to a few case reports. Some authors assume tha it is safe to perform an endarterectomy without acutely increasing the risk of aneurysm rupture while others reported a post-operative aneurysmal bleeding even for aneurysms smaller than 10 mm between some days and several months after endarterectomy. The aim of this paper is to analyse the factors involved in the particular ischemic episodes, the examination methods to be employed, and the optional management for each individual case on a literature review and own experience-based data.

Small unruptured cerebral aneurysms presenting with oculomotor nerve palsy

OBJECTIVE

Symptomatic unruptured aneurysms have been considered at relatively high risk for future rupture, and the majority of aneurysms that cause symptoms of mass effect are large. Unruptured aneurysms smaller than 1 cm in diameter sometimes cause neurological symptoms, but their clinical aspects remain obscure. In this article, we review our experience with small unruptured aneurysms presenting with oculomotor nerve palsy.

METHODS

Sixteen patients with unruptured aneurysms smaller than 1 cm presenting with oculomotor nerve palsy were included in this study. The patients' clinical profiles were reviewed, and factors affecting the recovery of oculomotor function were determined.

RESULTS

The mean size of the aneurysms was 5.8 +/- 1.4 mm. Eleven patients (68.8%) had preceding retrobulbar pain. Fifteen patients underwent successful microsurgical clipping or intravascular embolization, but one patient died of aneurysm rupture before surgery. Seven patients (43.8%) had a complete recovery of oculomotor function, six (37.5%) had an incomplete recovery, and two (12.5%) remained unchanged after treatment. The mean interval between the onset of oculomotor nerve palsy and treatment was 4.7 +/- 3.3 days in patients with complete recovery, 24.2 +/- 15.5 days in patients with incomplete recovery, and 41.0 +/- 12.7 days in unchanged patients. Early surgery resulted in more complete recovery of neural function (P < 0.01).

CONCLUSION

Unruptured aneurysms smaller than 1 cm can cause neurological symptoms of mass effect. We recommend timely surgery, preferably within 5 days, to avoid not only aneurysm rupture but also functional disability even in patients with unruptured aneurysms smaller than 1 cm.

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.

Surgical management of unruptured basilar artery bifurcation aneurysms

The basilar artery (BA) bifurcation is the most common site for aneurysms arising from the posterior circulation. Their inhospitable location, nested within the narrow confines of the interpeduncular fossa anterior to the brainstem, coupled with the rich network of adjacent critical thalamoperforating arteries irrigating the midbrain and thalamus, pose difficult anatomical obstacles for the surgeon.

The age old adage that the only cure for intracranial aneurysms remains exclusion from circulation before rupture still holds true. Although management of unruptured aneurysms in general is still controversial, unruptured aneurysms of the BA bifurcation can be treated surgically with acceptable rates of morbidity. The clinician must gather and weigh all clinical, pathological, and radiological data when formulating recommendations for the individual patient.

In the present report the authors describe their current technique for the surgical management of unruptured BA bifurcation aneurysms; this represents the culmination of the senior author's (N.K.) experience in the management of both ruptured and unruptured BA bifurcation aneurysms. A modified, right-sided subtemporal transtentorial approach has been adopted in all cases of isolated unruptured BA bifurcation aneurysms. Technical nuances are described.

Genetics of intracranial aneurysm

Subarachnoid hemorrhage (SAH) secondary to ruptured saccular intracranial aneurysm (IA) is a complex trait, with both genetic and environmental risk factors playing an important part. The 30-day mortality rate of patients with SAH is 40% to 44%, with many survivors suffering from major disability. Because most of the mortality after SAH is caused by rapid and massive brain injury from the initial bleeding, primary prevention of aneurysm formation and rupture is of paramount importance. This article reviews the evidence supporting a genetic predisposition to SAH from saccular IA, the conditions commonly associated with saccular IA, and the search for genetic risk factors.

Photothermal properties of shape memory polymer micro-actuators for treating stroke

BACKGROUND AND OBJECTIVES

In this paper the photothermal engineering issues of novel shape memory polymer (SMP) microactuators for treating stroke are presented. The engineering issues for using lasers to heat and subsequently actuate these SMP devices are presented in order to provide design criteria and guidelines for intravascular, laser activated SMP devices.

MATERIALS AND METHODS

A total of three devices will be presented: two interventional ischemic stroke devices (coil and umbrella) and one device for releasing embolic coils (microgripper). The optical properties of SMP, methods for coupling laser light into SMP, heating distributions in the SMP devices, and the impact of operating the thermally activated material in a blood vessel are presented.

RESULTS

Actuating the devices requires device temperatures in the range of 65-85 degrees C. Attaining these temperatures under flow conditions requires critical engineering of the SMP optical properties, optical coupling into the SMP, and device geometries.

CONCLUSION

Laser-activated SMP devices are a unique combination of laser-tissue and biomaterial technologies. Successful deployment of the microactuator requires well-engineered coupling of the light from the diffusing fiber through the blood into the SMP.

Treatment of asymptomatic unruptured intracranial aneurysms. A clinical decision analysis

SUMMARY

The indication of preventive surgery for patients who harbor asymptomatic un ruptured intracranial aneurysms remains controversial. To evaluate the benefit of this treatment, we investigated the management outcome in 128 patients with 157 unruptured aneurysms. Surgery was planned in patients 70 years old or younger without serious systemic complications. A total of 77 patients underwent surgery including four endovascular interventions, and conservative management was chosen in 51 patients. There was no mortality and 6.5% morbidity as postoperative results, and no complication was found after endovascular treatment. Among the patients in conservative management, four patients suffered from subsequent rupture during the total follow-up period of 148 person-years. The annual rupture rate was estimated at 2.7%. According to the clinical decision analysis based on our data, preventive surgery is beneficial for a Japanese 70 years old or younger. However, the expected utility decreases if the rupture rate is set at 0.5% or 0.05%, posing a doubt about the benefit of the surgery. Decision analysis provides an aid for logical and objective choice in the management of unruptured aneurysms. The actual risk of rupture has a major impact on decision making in therapeutic strategy.

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.

Prevalence of asymptomatic incidental aneurysms: review of 4568 arteriograms

OBJECT

The prevalence of unruptured cerebral aneurysms is unknown, but is estimated to be as high as 5%. The goal of this study was to determine the prevalence of asymptomatic incidental aneurysms.

METHODS

The authors studied all cerebral arteriography reports produced at a single institution, the University of Virginia, between April 1969 and January 1980. A review of 3684 arteriograms demonstrated 24 cases of asymptomatic aneurysms, yielding a prevalence rate of 0.65%. The majority (67%) of the 24 patients harboring unruptured aneurysms were women. More than 90% of the unruptured aneurysms were located in the anterior circulation and in locations similar to those found in patients with ruptured aneurysms. Nearly 80% of the aneurysms were smaller than 1 cm in their greatest diameter. The frequency of asymmetrical unruptured aneurysms (0.6-1.5%) was constant throughout all relevant age ranges (35-84 years).

CONCLUSIONS

While keeping in mind appropriate caveats in extrapolating from these data, the prevalence rate of asymptomatic unruptured aneurysms found in the present study allows an estimation of the yearly rate of rupture of these lesions. The authors suggest that this yearly rate of rupture falls within the range of 1 to 2%.