Deepa P. Bhupali, MD

Backes D, Vergouwen MDI, Velthuis BK, van der Schaaf IC, Bor ASE, Ale Algra A, and Rinkel GJE. Difference in Aneurysm Characteristics Between Ruptured and Unruptured Aneurysms in Patients With Multiple Intracranial Aneurysms. Stroke. 2014

Backes et al. set out to more clearly define risk factors for aneurysm rupture – information which could significantly impact patients’ lives. They compared geometric and morphological characteristics of ruptured and unruptured aneurysms within the same patient in a cohort of patients who had aneurysmal SAH and multiple unruptured intracranial aneurysms. One of their most interesting findings is that although aneurysm size was the strongest risk factor associated with rupture, the aneurysm that ruptured was not the largest aneurysm in one third of their cases.

These results are meaningful. In clinical practice, many decisions regarding aneurysm treatment are based on size; however, it’s clear that size alone is not enough to accurately predict risk of rupture. 

When the authors adjusted for size and location of aneurysm, they found that a higher aspect ratio and an irregular shape were strongly associated with risk of rupture. But, as the authors note, it is difficult to truly know if aneurysm shape and size are the result rather than the cause of rupture. This again highlights the fact that the current tools and methods used to characterize aneurysms are limited.

Bottom line: We need better ways to evaluate the risk of aneurysm rupture and relying solely on size is not sufficient.