Natural History Of Unruptured Aneurysms Research Articles

Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) represents a small portion of cerebrovascular disease but a disproportionally large percentage of the morbidity and mortality. The overall prognosis depends on the volume of the initial bleeding, rebleeding, and the degree of delayed cerebral ischemia. The presence of cardiac manifestations and neurogenic pulmonary edema at the initial presentation indicates a higher degree of severity and systemic complications. This review covers the pathophysiology, stabilization and assessment, diagnosis and treatment, and disposition and outcomes of SAH. Figures show common saccular aneurysm locations, a noncontrast head computed tomographic scan of an SAH, an angiogram and surgical clipping of a broad-based anterior communicating aneurysm, and a three-dimensional reconstruction angiogram of a complex anterior communicating aneurysm with additional imaging of endoscopic stent-assisted coiling of the same aneurysm. Tables list the natural history of unruptured aneurysms and the annual risk of rupture, common clinical features and syndromes related to aneurysm location, the World Federation of Neurologic Surgeons grading system, the Hunt and Hess grading systems, and the Fisher scale. This review contains 4 highly rendered figures, 5 tables, and 144 references. Key words: aneurysm rupture, cerebral aneurysm, cerebral vasospasm, Fisher scale, Glasgow Coma Scale assessment, Hunt and Hess grading criteria, subarachnoid hemorrhage, World Federation of Neurologic Surgeons grading scale Key Advances CT angiography is an emerging technology that has the diagnostic advantage of being non-invasive. The diagnostic accuracy of CTA varies widely and when compared to the standard digital subtraction angiography (DSA) the sensitivity and specificity range from 77% to 100% and 87%-100% respectively. The 2012 AHA guidelines and the 2011 Neurocritical care society (NCS) consensus guidelines recommend that from the time of symptom onset to securing of the aneurysm, the blood pressure be controlled with a titratable agent with a goal systolic blood pressure of less than 160mmHg or a MAP of less than 110mmHg. Cardiac abnormalities are common following acute SAH. Subendocardial ischemia may result from autonomic stimulation from the brain and circulating catecholamine surge, resulting in an abnormal ECG in 50% to 100% of patients with SAH in the acute phase depending on severity. The International Subarachnoid Aneurysm Trial ISAT was a landmark study that looked at aSAH repair comparing surgical clipping with endoscopic coiling and demonstrated a mortality benefit with coiling in the right patient population.

Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) represents a small portion of cerebrovascular disease but a disproportionally large percentage of the morbidity and mortality. The overall prognosis depends on the volume of the initial bleeding, rebleeding, and the degree of delayed cerebral ischemia. The presence of cardiac manifestations and neurogenic pulmonary edema at the initial presentation indicates a higher degree of severity and systemic complications. This review covers the pathophysiology, stabilization and assessment, diagnosis and treatment, and disposition and outcomes of SAH. Figures show common saccular aneurysm locations, a noncontrast head computed tomographic scan of an SAH, an angiogram and surgical clipping of a broad-based anterior communicating aneurysm, and a three-dimensional reconstruction angiogram of a complex anterior communicating aneurysm with additional imaging of endoscopic stent-assisted coiling of the same aneurysm. Tables list the natural history of unruptured aneurysms and the annual risk of rupture, common clinical features and syndromes related to aneurysm location, the World Federation of Neurologic Surgeons grading system, the Hunt and Hess grading systems, and the Fisher scale. This review contains 4 highly rendered figures, 5 tables, and 144 references. Key words: aneurysm rupture, cerebral aneurysm, cerebral vasospasm, Fisher scale, Glasgow Coma Scale assessment, Hunt and Hess grading criteria, subarachnoid hemorrhage, World Federation of Neurologic Surgeons grading scale

Incidence of Aneurysmal Subarachnoid Hemorrhage with Procedures Requiring General Anesthesia in Patients with Unruptured Intracranial Aneurysms

Background: The role of general anesthesia in precipitating aneurysm rupture is not clearly defined. In this study, we aimed to assess the natural history of unruptured aneurysms in patients undergoing non-aneurysm-related procedures requiring general anesthesia. Methods: Retrospective review of consecutive patients with untreated intracranial aneurysms that underwent unrelated surgery with operative note documentation of general anesthesia. Events of intraoperative and postoperative subarachnoid hemorrhage were recorded to determine the incidence of rupture. Results: A total of 110 patients harboring 134 unsecured aneurysms were studied. The mean age was 56.5 years (range, 17–92), and 68% were women (n = 75/110). Mean aneurysm size was 3.5 mm (range 1.5–17). A total of 208 procedures were performed under general anesthesia. There were no events of subarachnoid hemorrhage in 5.7 years of follow-up. Conclusion: In our study, general anesthesia did not precipitate aneurysm rupture, and there were no instances of subarachnoid hemorrhage during the follow-up period. Our results suggest a benign natural history for aneurysms undergoing unrelated general anesthesia. However, this should be interpreted with caution given limitations related to our small sample size and retrospective study design.

Should Patients with Autosomal Dominant Polycystic Kidney Disease Be Screened for Cerebral Aneurysms?

Autosomal dominant polycystic kidney disease is a genetic disorder affecting 1 in 1000 people worldwide and is associated with an increased risk of intracranial aneurysms. It remains unclear whether there is sufficient net benefit to screening this patient population for IA, considering recent developments in imaging and treatment and our evolving understanding of the natural history of unruptured aneurysms. There is currently no standardized screening protocol for IA in patients with ADPCKD. Our review of the literature focused on the above issues and presents our appraisal of the estimated value of screening for IA in the setting of ADPCKD.

Analysis by Categorizing or Dichotomizing Continuous Variables Is Inadvisable: An Example from the Natural History of Unruptured Aneurysms

In medical research analyses, continuous variables are often converted into categoric variables by grouping values into ≥2 categories. The simplicity achieved by creating ≥2 artificial groups has a cost: Grouping may create rather than avoid problems. In particular, dichotomization leads to a considerable loss of power and incomplete correction for confounding factors. The use of data-derived "optimal" cut-points can lead to serious bias and should at least be tested on independent observations to assess their validity. Both problems are illustrated by the way the results of a registry on unruptured intracranial aneurysms are commonly used. Extreme caution should restrict the application of such results to clinical decision-making. Categorization of continuous data, especially dichotomization, is unnecessary for statistical analysis. Continuous explanatory variables should be left alone in statistical models.

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.

Defining the natural history of unruptured aneurysms.

Despite advances in neurosurgical technique, neuroanesthesia, and neurocritical care and the evolution of endovascular therapy, aneurysmal subarachnoid hemorrhage (SAH) continues to be associated with poor outcome in a majority of patients. The 30-day mortality rate for SAH approaches 50%,1,2 and nearly one half of survivors suffer major neurologic morbidity. These dismal outcomes are especially significant since SAH affects a younger cohort than ischemic stroke, and the impact is magnified in terms of lost quality life-years. On the basis of an annual incidence of 10/100 000, it is estimated that nearly 30 000 Americans will have an aneurysmal SAH each year.3 Although prevention of SAH would seem to be the most effective strategy for reducing morbidity,4 the optimal management of patients with unruptured cerebral aneurysms remains controversial and requires a precise assessment of the risks for various treatment strategies and accurate knowledge of the natural history of the disease process. Unfortunately, the natural history of unruptured cerebral aneurysms is poorly understood. Until recently, few systematic studies have enrolled a sufficient number of patients for follow-up, and larger retrospective population analyses2,5 were done prior to the advent of current imaging modalities. Five years ago, the first phase of the International Study of Unruptured Intracranial Aneurysms (ISUIA) study provided a retrospective analysis of previously identified patients with unruptured aneurysms not receiving treatment, as well as a temporal snapshot of a cohort of patients followed prospectively over a 4-year period.6 The study reported what many considered to be remarkably low rates of aneurysm rupture (especially for aneurysms <10 mm in diameter) and a remarkably high rate of complications for surgical treatment, thus prompting a longer-term …

Intracranial Aneurysms

This article reviews the current knowledge of the pathogenesis, clinical features, diagnostic evaluation, and treatment of intracranial aneurysms. The vast majority are acquired lesions, likely as a result of hemodynamic stress on the relatively unsupported bifurcations of the intracranial arteries. Cigarette smoking is an emerging important risk factor for their development. The natural history of unruptured aneurysms is controversial and may be subject to revision. A benign perimesencephalic pattern of subarachnoid hemorrhage has been recognized that usually is not due to a ruptured aneurysm. Current treatment includes surgical clipping and endovascular treatment with Guglielmi detachable coils, which produces comparable results in some instances. Epidemiologic studies suggest that the outcome of patients with aneurysmal subarachnoid hemorrhage remains poor, with a 30-day death rate of 45%, although the outcome of patients who reach the hospital alive may have improved in recent years.

Treatment strategy for patients with unruptured intracranial aneurysms.

The increased sensitivity of neuroimaging techniques has enabled the more frequent diagnosis of unruptured aneurysms. Because the most devastating complication of an unruptured aneurysm is subarachnoid hemorrhage, it has been considered desirable to treat these aneurysms before they rupture. However, the optimal treatment strategy for patients with unruptured aneurysms remains controversial. The management decision requires knowledge of the natural history and an accurate assessment of the risks related to various treatment options. On December 10, 1998 the New England Journal of Medicine published an article by the International Study of Unruptured Intracranial Aneurysms Investigators. The study retrospectively assessed the natural history of unruptured aneurysms in 1449 patients; in addition, treatment-related mortality and morbidity were examined in a prospective cohort of 1172 patients. The major finding was that the rate of rupture for aneurysms smaller than 10 mm in diameter in patients with no history of subarachnoid hemorrhage was 0.05% per year, and that the mortality and morbidity associated with surgery greatly exceeded the risk of rupture in such patients. This report has generated tremendous controversy in the treatment of unruptured aneurysms and has influenced our decision making. The results of this study are critically analyzed and potential flaws presented. To develop recommendations for treatment, the literature was reviewed. The conclusion of this search is that there is insufficient evidence to recommend a standard of management. Therapeutic guidelines are provided, particularly for patients with small incidental aneurysms and no history of subarachnoid hemorrhage.

Embolization of Non-Ruptured Aneurysms

Options for treatment of intracranial aneurysms have expanded with the advent of the Guglielmi Detachable Coil (GDC) eight years ago. We have reviewed 435 cases of intracranial aneurysms treated at UCSF by endovascular means using the GDC system. Of these, 55% represent anterior circulation aneurysms, and 45% are located in the posterior circulation. Additionally, 55% of the aneurysms presented with subarachnoid hemorrhage (SAH) and 45% were unruptured. Factors which hindered optimal coiling include the following: wide aneurysm neck in relation to the overall aneurysm size, mural thrombus, giant aneurysm, arteries originating from the aneurysm sac, and middle cerebral location. After initial experience was gained, we tended to avoid these aneurysms especially in the non-ruptured group. This may be especially important in light of new epidemiological data suggesting that the natural history of unruptured aneurysms is significantly lower than previously thought. New technical developments which may reduce the risk of treating unruptured aneurysms include the two-dimensional coil, the three-dimensional coil, the balloon-assist technique for wide-necked aneurysms, and combined stent-coil procedures.

Unruptured congenital aneurysm of the sinus of valsalva presenting with pulmonary stenosis

Congenital aneurysm of the sinus of Valsalva is a rare cardiovascular anomaly. It is usually silent until rupture occurs. The natural history of unruptured aneurysm of the sinus of Valsalva is still not clear, and the therapeutic strategy is uncertain. Here we reported a case of unruptured aneurysm of the sinus of Valsalva which was correctly diagnosed before invasive diagnostic procedures. A 30-year-old female noted mild palpitation and dyspnea for 1 month. Physically, a grade 3/6 systolic ejection murmur at upper left sternal border was detected. Echocardiography revealed dilatation and irregular protrusion of the right sinus of Valsalva encroaching on right ventricular outflow tract to cause obstruction. With these findings, unruptured aneurysm of the sinus of Valsalva with pulmonary stenosis was diagnosed. Cardiac catheterization and angiography confirmed the diagnosis. The aneurysm was repaired with a Dacron patch with good results. It is concluded that sinus of Valsalva aneurysm can be diagnosed by echocardiography before its rupture so as to render a proper management for this potentially life-threatening anomaly. Cathet. Cardiovasc. Intervent. 46:210–213, 1999. © 1999 Wiley-Liss, Inc.

Natural history of unruptured intracranial aneurysms: a long-term follow-up study.

To investigate the natural history of unruptured aneurysms and predictive risk factors determining subsequent rupture, the authors followed 142 patients with 181 unruptured aneurysms until death or subarachnoid hemorrhage intervened, or for at least 10 years after the unruptured aneurysm was diagnosed. Six patients had a symptomatic aneurysm, five had an incidentally discovered aneurysm, and 131 had multiple aneurysms, of which the ruptured lesion was clipped at the beginning of the follow-up study. The median follow-up time was 13.9 years (range 0.8 to 30.0 years). During 1944 patient-years of follow-up study there were 27 first episodes of hemorrhage from a previously unruptured aneurysm, giving an average annual rupture incidence of 1.4%. Fourteen of these bleeding episodes were fatal. The cumulative rate of bleeding was 10% at 10 years, 26% at 20 years, and 32% at 30 years after the diagnosis. The only predictor for the rupture was the size of the aneurysm (p = 0.036). However, in patients with multiple aneurysms (the main subgroup) the only variable that tended to predict rupture was the age of the patient: risk of rupture was inversely associated with age (p = 0.080). The median diameter of the aneurysms was 4 mm at the beginning of the follow-up period, both in those with and those without a later hemorrhage. During the angiographic monitoring period, a ruptured aneurysm significantly (p < 0.001) increased in size in 17 patients with hemorrhage but aneurysms did not increase significantly in 14 patients without hemorrhage. In addition, a new aneurysm was found in six of 31 patients. The authors conclude that an unruptured aneurysm should be operated on, irrespective of its size, if it is technically possible and the patient's age and concurrent diseases are not contraindications to surgery.