Incidental Intracranial Aneurysms Research Articles

Frequency of incidental intracranial aneurysms in neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is often mentioned among the heritable connective tissue disorders associated with intracranial aneurysms, but the association has not been firmly established. We therefore reviewed a contemporary series of hospitalized patients with NF1, many of whom underwent brain magnetic resonance imaging (MRI). We identified patients with NF1 who were hospitalized at Cedars-Sinai Medical Center, Los Angeles, California, between January 1, 1997 and December 31, 2001 through the hospital's centralized medical records system using DRG codes. The mean age of the 39 patients was 30.4 years, and 22 patients had undergone MRI of the brain for the evaluation of symptoms due to the presence of central or peripheral nervous system tumors. Incidental intracranial aneurysms were detected in 2 (5%) of the 39 patients. Limiting the patient population to the 22 patients who had undergone MRI examination, the detection rate was 9%. This was significantly (P < 0.005) higher than the aneurysm detection rate in a control population (0/526 [0%]) of patients hospitalized for primary or secondary brain tumors, all of whom had undergone MRI examination. Our study suggests that patients with NF1 are at an increased risk of developing intracranial aneurysms.

Contemporary management of incidental intracranial aneurysms

The management of unruptured intracranial aneurysms has changed significantly in recent years and continues to evolve. The three main factors that have affected the management of unruptured intracranial aneurysms are as follows: 1) increased availability of noninvasive imaging technology, resulting in increased detection of incidental aneurysms; 2) improved understanding of the natural history of unruptured aneurysms; and 3) the advent of neuroendovascular therapy. In this report, the authors discuss the implications of these factors in the diagnosis and management of truly incidental, asymptomatic aneurysms and review the current practice patterns at their institution. Historical and current articles regarding noninvasive neuroimaging, aneurysm screening, endovascular and surgical therapy, and the natural history of unruptured aneurysms were reviewed. Current practices used for diagnosis and management of incidental aneurysms at the authors' institution were also reviewed. The management of incidental intracranial aneurysms has become an increasingly controversial subject in recent years. Improvements in noninvasive imaging resulting in detection of an increasing number of incidental aneurysms, the establishment of endovascular therapy as an attractive alternative to surgery, and studies indicating a more benign natural history for unruptured aneurysms than previously thought have led to significant changes in neurosurgical practice. Safety and long-term efficacy are the goals of treatment for unruptured aneurysms. Until conclusive studies are completed, the experience of the neurovascular team at each institution and the art of patient selection for treatment will continue to play a fundamental role in the management of these lesions.

Patients With Small, Asymptomatic, Unruptured Intracranial Aneurysms and No History of Subarachnoid Hemorrhage Should Be Treated Conservatively

It is foolhardy to remove from consideration of treatment any aneurysm solely because its maximal size is <10 mm or 7 mm. Annually, ≥15 000 American patients have subarachnoid hemorrhage (SAH) from aneurysms with a maximum diameter <7 mm and consequently experience irreparable morbidity and severe mortality. The majority of their aneurysms were, of course, unruptured, single, asymptomatic, and even smaller at some point before rupture. If the rupture rates for <10-mm aneurysms in International Study of Unruptured Intracranial Aneurysm (ISUIA) I1 or <7 mm in ISUIA II2 are used with the known number of ruptured aneurysms of these sizes admitted each year to calculate the prevalence of such small aneurysms in American adults, there is an unbelievably high result: in the range of 7% to 14%. Previous best estimates of prevalence on the basis of retrospective and prospective, radiological and pathological data have been ≈2% for all sizes of aneurysms and for those <10 mm, less than 1%. In autopsy studies, unruptured aneurysms have not outnumbered ruptured ones; the reverse is the case.3 Between ISUIA I1 and ISUIA II,2 the rupture rate …

Treatment options of unruptured intracranial aneurysms.

Aneurysmal subarachnoid hemorrhage (SAH), despite improvements in surgical and medical treatment, is still a serious disease with high rates of case fatality (40% to 50%) and morbidity.1–3 Incidence rates of SAH have not changed during the CT era, and outcome of SAH has only modestly improved during the past few decades. Outcome is still determined mainly by severity of initial bleeding or early rebleeding.1–4 It seems that identification of preventive treatment methods for aneurysm rupture and of modifiable risk factors for SAH are important as means to influence incidence and outcome of this serious disease. Unruptured aneurysms, when incidentally discovered or found in connection with diagnosis of ruptured aneurysm (multiple aneurysm cases), have been operated on for 2 to 3 decades in western countries. In this way, the high case fatality and morbidity associated with a possible severe initial bleed can be eliminated by preventive surgical intervention. However, the natural history as well as risks of surgery of unruptured intracranial aneurysms are poorly known as are the risk factors for rupture because of lack of studies with sufficient number of patients and follow-up years. The Table shows cohorts of largest studies of rupture risk of unruptured intracranial aneurysms.4–8 The recently published prospective part of The International Study of Unruptured Intracranial Aneurysms (ISUIA; patient enrollment in 61 centers between 1991 and 1998)5 shows somewhat different results as compared with those of the retrospective part of ISUIA (in 53 centers between 1970 and 1991).7 In the prospective study,5 overall incidence of aneurysm rupture was higher (0.8% versus 0.3% per year); risk for rupture of vertebrobasilar aneurysms was lower (relative risk 2.3 versus 5.1 to 13.8 as compared with other aneurysms); mean follow-up time per patient was shorter (3.9 versus 8.3 years); there was a lower limit …

Intracranial aneurysms and ischemic cerebrovascular diseases

Objective: To investigate the relationship between intracranial aneurysm and ischemic cerebrovascular diseases, including strokes or transient ischemic attacks (TIAs). Method: 501 cases of intracranial aneurysms were reviewed retrospectively. Reasons for indicating the examinations, during which the incidental unruptured intracranial aneurysms were discovered, were collected. Result: 78 cases of unruptured, intracranial aneurysms were found in this study. Among the reasons for indicating the examinations, there were 29 cases of ischemic strokes and TIAs, which have a discovery rate of 37.18%. Only one incidental intracranial aneurysm (3.4%), located in the left middle cerebral artery that may have resulted in the ischemic stroke, was observed. Conclusion: Ischemic strokes and TIAs may act as clinical signs for the harboring of intracranial aneurysms. Most of the incidental intracranial aneurysms, however, might be coexisting disease with the ischemic cerebrovascular disease. Further studies are needed for revealing their intrinsic connection.

Is Carotid Angiography Necessary? Editors Disagree

The crux of the question addressed by our protagonists is whether the benefits of carotid angiography (CAA) outweigh the potential risks of the procedure compared with the noninvasive but less precise use of carotid Doppler ultrasound (DU) and lack of information about the intracranial circulation. The interpretation of the existing data can be, in part, philosophical: as Rothwell outlined, the net increase in risk for angiography is about 1 stroke for every 200 cases studied. Does this outweigh the benefits of intracranial vascular imaging provided by CAA? …

Identifying patients at risk for postprocedural morbidity after treatment of incidental intracranial aneurysms: the role of aneurysm size and location

A decision to treat incidental intracranial aneurysms (IIAs) relies on understanding the risks of treatment and weighing them against the those of aneurysm rupture. Whereas the natural history of IIAs is currently being studied, the risks associated with treating IIAs and factors associated with poor outcome need to be clearly established. In a consecutive series of 125 patients, 160 IIAs were treated either surgically (152 cases) or endovascularly (eight cases). Postprocedural morbidity was defined as a new neurological deficit associated with a score greater than or equal to 3 on the modified Rankin Scale or a score of less than 24 on the Mini-Mental Status Examination. Logistic regression analysis was used to identify predictors of postprocedural morbidity from retrospectively collected data on demographic, clinical, and radiographic characteristics. Treatment of IIAs was not associated with any mortality and was associated with postprocedural morbidity in 17 (13.6%) of 125 patients (early outcome) and eight (6.4%) of patients (late outcome). In the logistic-regression model, treatment of aneurysms (>or=13 mm) and posterior circulation aneurysms were independently associated with postprocedural morbidity. In patients in whom postprocedural neurological deficits developed, 12 (70.6%) of 17 and four (23.5% ) of 17 patients harbored aneurysms with broad or calcified necks, respectively. Age, comorbidities, multiple aneurysms, specific aneurysm location, and history of subarachnoid hemorrhage related to a different aneurysm were not significantly associated with poor outcome. The authors found that IIAs can be safely and effectively treated without causing mortality and with a lower morbidity rate than previously reported. A combination of radiographic variables may be helpful in identifying patients at risk for postprocedural morbidity.

Incidental Intracranial Aneurysms

This month's issue of Neurosurgical Focus concentrates on the management of intracranial aneurysms. The authors of the lead article review risk factors for postprocedure morbidity after treatment of incidental intracranial aneurysms. The findings in this manuscript document that incidental intracranial aneurysms may be treated and result in less morbidity than noted in the International Study of Unruptured Intracranial Aneurysms (ISUIA) report. The current study reviews a single group's experience with the management of intracranial aneurysms, taking a comprehensive team approach to the management of these lesions. Thus, it cannot easily be correlated with the ISUIA trial. The main finding of this study suggests that surgical management may involve a morbidity rate as high as reported in the ISUIA trial. The significant findings in this paper are that aneurysms greater than 13 mm in size and those with broad and calcified necks portend a greater risk for surgical morbidity. In the past, familial predisposition toward cerebral aneurysms has always been described in patients with two or more affected family members. The second manuscript in this issue suggests that first-degree relatives of patients with aneurysms are at higher risk for harboring intracranial aneurysms. The authors analyzed 96 relatives between the ages of 20 and 70 years with three-dimensional fast–spin echo magnetic resonance imaging for the presence of intracranial aneurysms. They found that the incidence of unruptured aneurysms was greater than anticipated. Given the noninvasive means available for evaluating patients, it may be of benefit to have all relatives undergo three-dimensional magnetic resonance imaging. The focus of the final vascular paper is on a single group's experience using the subtemporal approach for the management of basilar bifurcation aneurysms. The authors describe their modifications and technical nuances. This is a superb technical note from a group with considerable experience. This issue focuses on some of the finer details of intracranial aneurysm disease. The reader should gain a greater understanding of the management of patients with unruptured intracranial aneurysms and their first-degree relatives. Moreover, the technical surgical approach for basilar bifurcation aneurysms is superbly reviewed.

705 Identifying Patients at Risk for Post-Procedural Morbidity after Treatment of Incidental Intracranial Aneurysms: The Role of Aneurysm Size and Location

705 Identifying Patients at Risk for Post-Procedural Morbidity after Treatment of Incidental Intracranial Aneurysms: The Role of Aneurysm Size and Location

Embolization of incidental cerebral aneurysms by using the Guglielmi detachable coil system.

Guglielmi detachable coil (GDC) technology is a valuable therapeutic alternative to the surgical treatment of ruptured or incidental intracranial aneurysms. The authors describe their technical and clinical experience in the use of the GDC technique in patients who underwent endovascular occlusion for the treatment of incidentally found intracranial aneurysms. One hundred fifteen patients with 120 incidentally found intracranial aneurysms underwent embolization by means of the GDC endovascular technique. Ninety-one patients were females and 24 were males. Patient age ranged from 13 to 80 years. In 64 patients the incidental aneurysms were discovered when unrelated nonneurological conditions signaled the need for angiography or magnetic resonance angiography (Group 1). Twenty patients who presented with incidental aneurysms that were discovered during treatment for an acutely ruptured aneurysm underwent treatment of both types of aneurysm during the acute phase of subarachnoid hemorrhage (SAH) (Group 2). Sixteen patients with incidental aneurysms were treated during the chronic phase of SAH (Group 3). Group 4 included 15 patients who had incidental aneurysms associated with brain tumors or arteriovenous malformations. Angiographic results revealed complete or near-complete occlusion in 109 aneurysms (91%) and incomplete occlusion in five aneurysms (4%). Guglielmi detachable coil embolization was attempted unsuccessfully in six aneurysms (5%). One hundred nine patients (94.8%) remained neurologically intact or unchanged from their initial clinical status. Five patients (4.3%) deteriorated as a result of immediate procedural complications. All these complications occurred in the first 50 patients treated in the series. No clinical complications were observed in the last 65 patients. In one patient, a partially embolized aneurysm ruptured 3 years postprocedure. In Groups 1 and 3, the average length of hospitalization was 3.3 days. The evolution of GDC technology has proved to provide safe treatment of incidental aneurysms (a morbidity rate of 0% was achieved in the last 65 patients). The topography of the aneurysm and the clinical condition of the patient did not influence final anatomical or clinical outcomes. The GDC technology also confers a positive economic impact by decreasing hospital length of stay and by eliminating the need for postembolization intensive care.

Carotid Artery Tandem Lesions Frequency and Consequences for Endarterectomy

We determined the frequency of tandem carotid lesions within the carotid siphon, common carotid artery and proximal intracerebral arteries as well as incidental intracranial saccular aneurysms. We also determined the consequence of a tandem lesion on the surgeon's decision-making process when a hemodynamically significant stenosis or aneurysm was detected during the preoperative evaluation.

Embolization of incidental cerebral aneurysms using the Guglielmi detachable coil system

Guglielmi detachable coil (GDC) technology is a valuable therapeutic alternative to the surgical treatment of ruptured or incidental intracranial aneurysms. The authors describe their technical and clinical experience in the utilization of the GDC technique in patients who underwent endovascular occlusion for the treatment of incidentally found intracranial aneurysms. One hundred fifteen patients with 120 incidentally found intracranial aneurysms underwent embolization using the GDC endovascular technique. Ninety-one patients were female and 24 were male. Patient age ranged from 13 to 80 years. In 64 patients the incidental aneurysms were discovered when unrelated nonneurological conditions indicated the need for angiography or magnetic resonance angiography (Group 1). Twenty patients who presented with incidental aneurysms that were discovered during treatment for an acutely ruptured aneurysm were treated in the acute phase of subarachnoid hemorrhage (SAH) (Group 2). Sixteen patients with incidental aneurysms were treated during the chronic phase of SAH (Group 3). Group 4 included 15 patients who had incidental aneurysms associated with brain tumors or arteriovenous malformations. Angiographic results showed complete or near complete occlusion in 109 aneurysms (91%) and incomplete occlusion in five aneurysms (4%). Unsuccessful GDC embolization was attempted in six aneurysms (5%). One hundred nine patients (94.8%) remained neurologically intact or unchanged from initial clinical status. Five patients (4.3%) deteriorated due to immediate procedural complications (overall immediate morbidity rate). All of these complications occurred in the first 50 patients treated earlier in this series. No clinical complications were observed in the last 65 patients. Follow-up cerebral angiograms were obtained in 77 patients with 79 aneurysms. The median clinical follow-up period was 16.3 months. No recanalization was observed in the 52 completely occluded aneurysms. Of the 22 aneurysms with small neck remnants, eight (36%) showed further thrombosis, 7 (32%) remained anatomically unchanged, and seven (32%) showed recanalization due to compaction of the coils. In one patient, a partially embolized aneurysm ruptured 3 years postembolization. In Groups 1 and 3, the average length of hospitalization was 3.3 days. The evolution of the GDC technology has proved to provide safe treatment of incidental aneurysms (a morbidity rate of 0% was achieved in the last 65 patients). The topography of the aneurysm and the clinical condition of the patient did not influence final anatomical or clinical outcomes. The GDC technology also confers a positive economical impact by decreasing hospital length of stay and by eliminating the need for postembolization intensive care unit care.

Risk of harboring an unruptured intracranial aneurysm.

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. 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. 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. 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.

O-3-31 - The prevalence of incidental intracranial aneurysms in general population, in families with one, and in families with two or more known subarachnoid hemorrhage cases

O-3-31 - The prevalence of incidental intracranial aneurysms in general population, in families with one, and in families with two or more known subarachnoid hemorrhage cases

Familial intracranial aneurysms

We set out to determine the prevalence of incidental intracranial aneurysms in first-degree relatives aged 30 years or more of people with intracranial aneurysms, and to see if polycystic kidney disease contributes to the aggregation of familial intracranial aneurysms. 91 families with two or more affected members had previously been identified from a 14 year series of 1150 intracranial aneurysm patients treated at the University Hospital of Kuopio, Finland. Magnetic resonance angiography was used as a preliminary screening method, followed by conventional four-vessel angiography to verify suspected aneurysms. Participants were also screened for polycystic kidneys by ultrasonography. Incidental aneurysms were detected in 40 individuals: 38 of 438 individuals from 85 families without polycystic kidney disease or other diagnosed heritable disorders, and two of 22 individuals from six families known to have polycystic kidney disease. The crude and age-adjusted prevalence of incidental intracranial aneurysms among screened first-degree relatives was 8.7 (SE 1.3)% (95% CI 6.2-11.7) and 9.1 (1.4)% (6.2-11.7), respectively, for the familial group and the crude prevalence for the polycystic kidney group was 9.1 (6.1)% (1.1-29.2). Our results demonstrate a high prevalence of incidental intracranial aneurysms among first-degree relatives aged 30 years or older of patients with the condition and indicate that the risk of having an aneurysm is about four times higher for a close relative than for someone from the general population. Also, polycystic kidney disease families are a small fraction of the familial intracranial aneurysm families.

Familial subarachnoid hemorrhage in east Finland, 1977-1990.

The familial occurrence of cerebral aneurysms in a defined clinical group of 1150 patients from a defined catchment area was studied. Two or more proven aneurysmal subarachnoid hemorrhage (SAH) patients within the same family were included. Of these 1150 patients, 113 (10%) had a proven familial occurrence of aneurysmal SAH. These 113 patients form 91 SAH families with a total of 203 aneurysm patients. Fifty-four percent of the patients were female, and the mean age in female patients was 49 years and in male patients was 44 years. In 23% of the families, three or more members were identified as having cerebral aneurysms. Middle cerebral artery aneurysms were the most common type (47%). Based on the high incidence (10%) of familial intracranial aneurysms among SAH patients, a prospective study of healthy family members for incidental intracranial aneurysms was performed, with positive findings of 12%.

Autopsy study of unruptured incidental intracranial aneurysms

The autopsy files and preparations of unruptured incidental intracranial aneurysms seen at the Montefiore Medical Center between 1951 and 1987 were reviewed. There were 84 patients with 102 unruptured aneurysms in a total of 10,259 autopsies, giving a prevalence of 0.8%. Sixteen of the 84 (19%) had multiple aneurysms. The thickness of walls of aneurysms could be estimated in 78 of 102 aneurysms, and was determined to be either thin or thin and thick in 71 aneurysms. In this study, four noteworthy factors were found: (1) the incidence of unruptured aneurysms was higher in elderly patients aged 60 years or older, and the peak percentage was 1.2% in the seventh decade; (2) aneurysms occurred more frequently in females than males, with a ratio of 53: 31; (3) the most common site of aneurysms was the middle cerebral artery; 37 of 102 aneurysms (36%) occurred on it; and (4) the rate of small aneurysms was very high; 50 of 93 aneurysms (54%) were 4 mm or less in diameter, and 33 aneurysms (35%) were 5–9 mm in diameter. However, relationships could not be found between age distribution and location, size, or thickness of walls; between gender and size or thickness of walls; between location and size or thickness of walls; or between size and thickness of walls. Based on published statistics on subarachnoid hemorrhage and this study, the rupture rate of unruptured aneurysms seems to be very low. Although the risk of rupture may be relatively low in small aneurysms, its low risk probably cannot be explained adequately by morphological examination only.

閉塞性脳血管病変と脳動脈瘤合併症の臨床的検討

Special strategic consideration is necessary for the surgical treatment cases of complicated occlusive cerebro-vascular disease with intracranial aneurysm because the direct approach for such an aneurysm can easily give rise to cerebral infarction due to impending cerebral ischemia.A total 22 cases of complicated occlusive cerebro-vascular disease with intracranial aneurysm have been treated in our hospital in the past 10 years. Of those, nine started with apparent subarachnoid hemorrhage, and complicated occlusive cerebro-vascular disease was incidentally identified later (Group 1). In 13 other cases cerebral ischemic symptoms were first noted and incidental intracranial aneurysms were found by cerebral angiography later (Group 2).The ages of the patients ranged from 23 to 78 years old, with 15 of them being over 60 years old.(The average of group one was 65 and that of group two was 60.2).Of the patients in group one, neck clipping was the only surgical treatment necessary in four cases while three other cases required vascular reconstruction after neck clipping. Only three vascular reconstruction was done in one case. Another patient was simply treated conservatively. Postoperative symptomatic vasospasm was noted in three cases. The final results were excellent in three cases, good in two, poor in two and two cases the patient died. Apprent operative complication was seen in two patients; both had cerebral infarction due to injury of the arteriosclerotic small branch.The patients in group two were examined by cerebral angiography because of TIA in five cases, because of a minor stroke in 16 cases and because of a major stroke on one cases. Sixteen of those patients had surgical treatment of some sort: eight had neck clipping, five had coating of an aneurysm, one had STA-MCA anastosis, and two had neck clipping with additional STA-MCA anastomosis. The surgical results were good in 12 cases, poor in one and one patient died by because of late bleeding after coating.The surgical results give us warning that ruptured intracranial aneurysm complicated by occlusive cerebro-vascular disease should be operated on by careful and gentle maneuver, while an incidental intracranial aneurysm still requires radical operation in order to prevent subarachnoid hemorrhage.

椎骨脳底動脈系血管障害に合併した未破裂脳動脈瘤の4手術例

Among fifty-two angiographically examined patients with vertebro-basilar disorders, incidental intracranial aneurysms were found in five cases. Except for one patient who seemed unable to tolerate the operation, radical surgery was performed. These four cases were all males, ages ranging from 42-67. The vertebro-basilar disorders were of ischemic origin in three cases and hemorrhage in one case. These incidental aneurysms were located in the internal carotid artery, the middle cerebral artery and the anterior communicating artery. They were multiple in three cases. Intervals between strokes and operations were 51-81 days. In spite of a successful operation, mild to moderate disturbances of consciousness appeared in three cases. In two cases the problem subsided in a week, but in one case it persisted for two months. Fortunately, the final results in all cases were good. This transient deterioration of consciousness level might probably be ascribed to vertebro-basilar insufficiency which had once subsided but resumed due to the operative affections. Based on the experience with this small number of four cases, three points are suggested to prevent such hazards. 1) Extreme systemic hypotension as well as hypertension should be avoided during the operation. 2) GOF might be the anesthesia of choice in such cases. 3) The operation should be performed at a favorable time more than six months after the ictus.

Surgery of incidental intracranial aneurysms

A series of nine patients with an unruptured asymptomatic aneurysm not associated with a ruptured aneurysm is discussed. Three had giant aneurysms. Two patients had bilateral aneurysms of the middle cerebral artery. Five had solitary aneurysms of the middle cerebral artery. One had an aneurysm of the anterior communicating artery. One had an ophthalmic aneurysm. All aneurysms were clipped. Two operations were necessary in the two patients with bilateral aneurysms. There was no mortality and no significant morbidity. Clipping of the aneurysm is recommended for those patients who have no other serious illness that significantly increases the surgical risk. If a combination of pituitary tumor and aneurysm is found, a subfrontal instead of transsphenoidal approach should be considered so as to treat both the tumor and aneurysm at the same operation.