Article
Can ISUIA conclusions be applied to all anterior circulation aneurysms?
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Published: | April 28, 2011 |
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Objective: According to the International Study of Unruptured Intracranial Aneurysms (ISUIA), anterior circulation (anterior and middle cerebral and internal carotid artery) aneurysms less than 7mm in diameter carry a minimal risk of rupture. However, it is general neurosurgical experience that anterior communicating artery (Acom) aneurysms are frequent and most measuring 7 mm rupture. Do Acom aneurysms behave differently from other anterior circulation aneurysms?
Methods: We studied the prospectively recruited patients of the multicenter @neurIST project. The prevalence of unruptured aneurysms by location was compared between ISUIA reported figures and @aneurIST data. The odds ratio of aneurysm rupture was compared between Acom and anterior circulation, middle cerebral artery, internal carotid artery and posterior circulation locations. Average sizes of unruptured and ruptured aneurysms were calculated.
Results: Of 263 unruptured aneurysms in the @neurIST study, 207 (78%) were found in the anterior circulation (ISUIA 61%) and among these 48 (23%) were Acom aneurysms (ISUIA 10,3% for both anterior cerebral artery and Acom). The higher incidence of these aneurysms in the @neurIST collective was significant (p<0.001).The odds ratios for aneurysm rupture between the Acom and anterior circulation, middle cerebral artery, internal carotid artery and posterior circulation locations were 2.72, 3.96, 6.45 and 1.45, respectively. Unruptured and ruptured aneurysm sizes were 6.29±4.43 mm and 6.79±7.2 mm for the Acom, 5.98±4.56 mm and 6.76±8.35 mm for the internal carotid artery, 5.25±3.66 mm, 7.09±5.67 mm for the middle cerebral artery and 5.34±6.37 mm for the posterior circulation, respectively.
Conclusions: The prevalence of unruptured aneurysms of the anterior circulation is significantly higher in the @neurIST study than reported in ISUIA. Acom is the most frequent location of aneurysms observed in @neurIST. Acom aneurysms are mostly discovered after rupture and behave similarly to posterior circulation aneurysms in contrast to middle cerebral and internal carotid artery aneurysms. We therefore suggest that anterior circulation conclusions of ISUIA can not be applied to Acom aneurysms.