Risk factor analysis of growing unruptured intracranial aneurysms: A single center cohort study

Intradural unruptured intracranial aneurysms (UIA) can rupture and lead to subarachnoid hemorrhage. Previous studies suggest aneurysm growth being a strong risk factor for rupture. The natural history and the individual risk of growth of aneurysms remain controversial.

To analyze the time to growth and identify risk factors associated with growth of UIAs.

Prospectively collected data of 588 patients with a total of 858 UIAs followed up by imaging were analyzed. Patients and aneurysms were categorized in a growing or a stable cohort. Logistic and survival analyses were used to assess potential factors associated with UIA growth.

During a median follow-up of 3.4 years (IQR 1.3 - 6.6 years), 112 (13.1%) out of the 858 UIAs showed an increase in size or a change of morphology. Posterior circulation UIAs (OR 2.01 (1.15 - 3.52), p = 0.01), aneurysm size at diagnosis (OR 1.10 (1.04 - 1.16) per mm, p = 0.002) and arterial hypertension (OR 1.60 (1.03 - 2.49), p = 0.04) were significantly associated with growth. Survival analyses confirmed a time-dependent association with growth for posterior circulation UIAs (HR 3.9 (1.74 - 8.75), p = 0.002) and aneurysm size (HR 1.22 (1.13 - 1.31), p < 0.0001).

UIA location in the posterior circulation, a larger size at diagnosis and the presence of arterial hypertension are significant risk factors associated with UIA growth.