Sizes of ruptured and unruptured aneurysms in relation to their sites and the ages of patients

Restricted access

Object. The authors explore the risk of rupture in aneurysms categorized by size.

Methods. A computerized database of 945 patients with aneurysms treated between 1967 and 1987 was retrospectively established. All available clinical and radiological studies were abstracted. Because of the recent interest in the size of intracranial aneurysms in relation to their likelihood of rupture, the database was searched with respect to this parameter. In 390 patients representing 41% of all cases, aneurysms were measured by neuroradiologists at the time of diagnosis. In 78% of the 945 patients there was only one aneurysm, and of the 507 aneurysms that were measured, 60% were solitary. Of all patients, 86% had ruptured aneurysms. The average age of all patients was 47 years, and for those with ruptured aneurysms it was 46 years. Of the ruptured aneurysms, 77% were 10 mm or smaller, compared with 85% of the unruptured aneurysms. It was found that 40.3% of the ruptured aneurysms were on the anterior cerebral artery or anterior communicating artery, compared with 13% of the unruptured aneurysms. None of the cavernous internal carotid artery (ICA) aneurysms were ruptured and 65% of the ophthalmic artery (OphA) aneurysms were. Of the unruptured aneurysms, 15% were located in the cavernous ICA or the OphA. Of the ruptured aneurysms, 29% were on the middle cerebral artery, compared with 36% of the unruptured aneurysms. The mean size of ruptured and unruptured aneurysms showed no statistically significant increase with patient age, although the difference in size between the ruptured and unruptured aneurysms decreased with increasing age. The mean size of all ruptured aneurysms (10.8 mm) was significantly larger than the mean size of all unruptured aneurysms (7.8 mm, p < 0.001); the median sizes were 10 mm and 5 mm, respectively. The size of ruptured aneurysms in patients who died in the hospital was significantly larger than those in the patients who survived (12 mm compared with 9.9 mm, p = 0.004). Symptomatic unruptured aneurysms were significantly larger than incidental unruptured aneurysms (14.6 mm compared with 6.9 mm, p = 0.032), which were, in turn, larger than aneurysms that were unruptured and part of a multiple aneurysm constellation. Both ruptured and unruptured aneurysms were larger in male than in female patients, but not significantly.

Conclusions. Site and patient age, as well as lesion size, may affect the chance of rupture.

Article Information

Address reprint requests to: Bryce Weir, M.D., Division of Biological Sciences and the Pritzker School of Medicine, The University of Chicago, 5841 South Maryland, MC 1000, Chicago, Illinois 60637. email: Bweir1@delphi.bsd.uchicago.edu.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Bar graphs showing sizes of ruptured and unruptured aneurysms. It is shown in absolute numbers that 4 to 10 mm was the most common size for both ruptured and unruptured aneurysms. In percentage terms this was also true, but the 11 to 15-mm size is the most likely to be ruptured and those 3 mm or smaller are most likely to present in the unruptured aneurysm category.

  • View in gallery

    Graph showing smoothed estimates of size distribution curves. The y axis is scaled so that the area beneath each curve between any two sizes reflects the proportion of aneurysms in that size interval, and the area beneath each entire curve equals 1.

  • View in gallery

    Bar graphs showing sites of aneurysms. The most common ruptured aneurysms were in the ACoA (A Com), and MCA aneurysms were the most common unruptured aneurysms. The lesions most likely to be unruptured were in the cavernous ICA (Cav) and ACA (Other AC). The lesions most likely to be ruptured were in the ACoA and PerA (Peric). Bas = BA; IC Bif = ICA bifurcation; Oph = OphA; P Com = PCoA.

  • View in gallery

    Bar graphs showing ages of patients. The 40 to 59-year group was the most common for both ruptured and unruptured aneurysms in actual numbers and by percentage. Patients in the group with the largest percentage of ruptured aneurysms were 20 to 39 years old, and those with the highest percentage of unruptured aneurysms were 80 years or older.

  • View in gallery

    Scatterplots showing patient age compared with lesion size for ruptured (left) and unruptured aneurysms (right).

  • View in gallery

References

  • 1.

    Crompton MR: Mechanism of growth and rupture in cerebral berry aneurysms. Br Med J 1:113811421966Crompton MR: Mechanism of growth and rupture in cerebral berry aneurysms. Br Med J 1:1138–1142 1966

    • Search Google Scholar
    • Export Citation
  • 2.

    The International Study of Unruptured Intracranial Aneurysms Investigators: Unruptured intracranial aneurysms—risk of rupture and risks of surgical intervention. N Engl J Med 339:172517331998The International Study of Unruptured Intracranial Aneurysms Investigators: Unruptured intracranial aneurysms—risk of rupture and risks of surgical intervention. N Engl J Med 339:1725–1733 1998

    • Search Google Scholar
    • Export Citation
  • 3.

    Kassell NFTorner JC: Size of intracranial aneurysms. Neurosurgery 12:2912971983Kassell NF Torner JC: Size of intracranial aneurysms. Neurosurgery 12:291–297 1983

    • Search Google Scholar
    • Export Citation
  • 4.

    McCormick WFAcousta-Rua GJ: The size of intracranial saccular aneurysms. An autopsy study. J Neurosurg 33:4224271970McCormick WF Acousta-Rua GJ: The size of intracranial saccular aneurysms. An autopsy study. J Neurosurg 33:422–427 1970

    • Search Google Scholar
    • Export Citation
  • 5.

    Mozoi KKwak RSakamoto Tet al: Angiographical study of intracranial saccular aneurysms: with particular reference to their size and shape in Suzuki J (ed): Cerebral Aneurysms. Experiences with 1000 Directly Operated Cases. Tokyo: Neuron1979 pp 163170Mozoi K Kwak R Sakamoto T et al: Angiographical study of intracranial saccular aneurysms: with particular reference to their size and shape in Suzuki J (ed): Cerebral Aneurysms. Experiences with 1000 Directly Operated Cases. Tokyo: Neuron 1979 pp 163–170

    • Search Google Scholar
    • Export Citation
  • 6.

    Zeger SLLiang KY: Longitudinal data analysis for discrete and continuous outcomes. Biometrics 42:1211301986Zeger SL Liang KY: Longitudinal data analysis for discrete and continuous outcomes. Biometrics 42:121–130 1986

    • Search Google Scholar
    • Export Citation

TrendMD

Cited By

Metrics

Metrics

All Time Past Year Past 30 Days
Abstract Views 292 292 31
Full Text Views 237 237 0
PDF Downloads 142 142 0
EPUB Downloads 0 0 0

PubMed

Google Scholar