Treatment Strategy for Patients with Unruptured Intracranial Aneurysms.

Abstract

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.

Endovascular Coil Embolization of 435 Small Asymptomatic Unruptured Intracranial Aneurysms: Procedural Morbidity and Patient Outcome

“…Although the risk of rupture of asymptomatic UIAs and treatment morbidity and mortality have been extensively investigated, current evidence does not conclusively support a standard treatment strategy regarding asymptomatic UIAs; and in particular, the size at which an aneurysm becomes dangerous remains uncertain. 2,7 All current treatments carry risks, and recommendations for treatment versus observation are often difficult and controversial. Management decisions require accurate assessments of the risks of potential rupture, death, or disability due to rupture and the risks related to various treatment options to prevent an iatrogenic insult to patients destined to coexist peacefully with their unruptured aneurysms before dying of some other cause.…”

“…6,9 Moreover, current understanding does support the use of the small aneurysmal diameter as an independent criterion for management decision-making, though it is of undoubted importance. [5][6][7] The annual bleeding rate of asymptomatic UIAs has been investigated by retrospective and prospective studies. 2,3,5,[10][11][12][13][14][15][16][17][18][19][20][21] However, the estimates of UIA rupture risk vary considerably and appear to depend on study design, study population, and aneurysm characteristics.…”

“…In other studies, the annual ranges of rupture rates among patients with asymptomatic UIA varied from 0.05% to 2.3% per year. 7,21,22 In 1998, the International Study of Unruptured Intracranial Aneurysms (INSUIA) investigators reported the results of a large retrospective multicenter study on the natural course of asymptomatic UIAs. 5 In this study, the natural course of 1937 asymptomatic UIAs in 1449 patients was retrospectively assessed.…”

“…Although accumulating evidence points to the influence of aneurysm size on rupture risk in patients with UIA, the critical size at which an aneurysm becomes hazardous remains uncertain. [5][6][7] The risk of rupture may be relatively low for small aneurysms, but, to our knowledge, there is no evidence available that confirms their benign natural course or the merits of their conservative management. Estimates on the risk of UIA vary considerably, depending on study design, study population, and aneurysm characteristics.…”

Unruptured Intracranial Aneurysms: Some Questions Answered, Many Questions Remain

“…Some of these available guidelines 8 , cost-utility analyses 9 , and expert opinion recommendations 10,11 were published prior to the availability of more detailed aneurysm site-and size-specific natural history data, and morbidity and mortality of surgery and endovascular therapies from large prospective cohort studies. Most experts are in agreement that larger UIAs and those that are symptomatic should be considered for interventional treatment [12][13][14][15][16][17] because of the unacceptably high risk of UIA rupture with conservative management. Mathematical modeling of aneurysm natural history and management risks have been conflicting, with some suggesting that small unruptured aneurysms may not benefit from a procedure 18 .…”