Aneurysm growth and de novo aneurysms during aneurysm surveillance

Abstract

OBJECTIVE Many low-risk unruptured intracranial aneurysms (UIAs) are followed for growth with surveillance imaging. Growth of UIAs likely increases the risk of rupture. The incidence and risk factors of UIA growth or de novo aneurysm formation require further research. The authors retrospectively identify risk factors and annual risk for UIA growth or de novo aneurysm formation in an aneurysm surveillance protocol. METHODS Over an 11.5-year period, the authors recommended surveillance imaging to 192 patients with 234 UIAs. The incidence of UIA growth and de novo aneurysm formation was assessed. With logistic regression, risk factors for UIA growth or de novo aneurysm formation and patient compliance with the surveillance protocol was assessed. RESULTS During 621 patient-years of follow-up, the incidence of aneurysm growth or de novo aneurysm formation was 5.0%/patient-year. At the 6-month examination, 5.2% of patients had aneurysm growth and 4.3% of aneurysms had grown. Four de novo aneurysms formed (0.64%/patient-year). Over 793 aneurysm-years of follow-up, the annual risk of aneurysm growth was 3.7%. Only initial aneurysm size predicted aneurysm growth (UIA < 5 mm = 1.6% vs UIA ≥ 5 mm = 8.7%, p = 0.002). Patients with growing UIAs were more likely to also have de novo aneurysms (p = 0.01). Patient compliance with this protocol was 65%, with younger age predictive of better compliance (p = 0.01). CONCLUSIONS Observation of low-risk UIAs with surveillance imaging can be implemented safely with good adherence. Aneurysm size is the only predictor of future growth. More frequent (semiannual) surveillance imaging for newly diagnosed UIAs and UIAs ≥ 5 mm is warranted.

Aspirin associated with decreased rate of intracranial aneurysm growth

“…One explanation might be that, in the early stage following rupture, inflammation could play a protective role to remodel and seal the aneurysm wall, and during this early period aspirin's effect may not be protective. Another study of 192 patients harboring 234 unruptured IAs 35 showed that aspirin was protective for aneurysm growth (OR 0.72), but the findings did not reach statistical significance, potentially due to the small size of the cohort. On the other hand, in their multivariate analysis of 2334 patients, Hostettler et al 18 demonstrated that aspirin use was inversely associated with rupture (OR 0.65).…”

Preventing Rupture: Clipping of Unruptured Intracranial Aneurysms

“…Apparently, as an aneurysm swells, the risk of subsequent rupture rises [51]. However, according to Serrone et al, the single predictor of aneurysm enlargement was the initial size of the lesion, with the annual risk of growth being evaluated at a mean of 3.5%, though higher for larger aneurysms [52]. The morphology of the aneurysm was also incriminated in influencing the risk of rupture, especially the formation of a daughter sac, the shape of the sac, and regions possessing a thinned arterial wall [53].…”

Rapid Documented Growth of Aneurysm Bleb Led to Rupture of an Incidental Intracranial Anterior Communicating Artery Aneurysm

“…1,2,4 Aneurysm size is the most important risk factor followed by aneurysm configuration changes including aneurysm size progression. 4,5 In addition, the coexistence of an aneurysm-associated bleb, defined as an additional bulge on the aneurysm sac itself, is also described as a high risk factor for aneurysm rupture. [6][7][8] Based on radiologic flow models, the cause for such a bleb formation is thought to be the point of maximal wall shear stress within the aneurysm.…”