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  • Aneurysm Growth and De Novo Aneurysm Formation During an Aneurysm Surveillance Protocol

    Final Number:

    Joseph Carl Serrone MD; Ryan David Tackla MD; Yair Gozal MD, PhD; Dennis J Hanseman PhD; Steven L Gogela MD; Shawn Vuong MD; Jennifer Kosty BA, MD; Bryan Matthew Krueger MD; Aaron W Grossman M.D. PhD.; Andrew J. Ringer MD

    Study Design:

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2015 Annual Meeting

    Introduction: Due to observational studies finding small anterior circulation unruptured intracranial aneurysms (UIA) to be at low risk for subarachnoid hemorrhage (SAH), any UIAs are now followed with surveillance imaging. The incidence of growth of UIAs, incidence of de novo aneurysm formation, and risk factors for growth or de novo aneurysm formation require further research. We report our experience with an aneurysm surveillance protocol and review the literature on this topic.

    Methods: We retrospectively identified 192 patients with 234 UIAs that were recommended for observation with surveillance imaging and obtained at least 1 follow-up study. The incidence of UIA growth and de novo aneurysm formation was assessed. Risk factors for UIA growth and de novo aneurysm formation were evaluated. Patient compliance with the surveillance protocol and results after treatment were assessed.

    Results: Over 749 aneurysm-years of follow-up, 28 of 234 UIAs grew resulting in an annual risk of growth of 3.74%. At 6-months, 7.0% of patients had a growth of the aneurysm identified. Initial aneurysm size was the only predictor of aneurysm growth (p=0.002). The incidence of growth for UIAs < 5 mm versus UIA = 5 mm was 1.6% and 8.7% per aneurysm-year, respectively. Over 614 patient-years of follow-up, 4 de novo aneurysms formed in 192 patients resulting in a 0.64% annual risk of de novo aneurysm formation. The rate of aneurysm growth or de novo aneurysm formation was 5.0% per patient-year of follow-up. Patient compliance with our protocol was 65% with younger age predictive of patient compliance (p = 0.01).

    Conclusions: Observation of low risk UIAs with surveillance imaging can be safely implemented into clinical practice with good adherence. More frequent surveillance imaging for newly diagnosed UIAs is warranted. Future guidelines should recommend a specific frequency and duration of aneurysm surveillance.

    Patient Care: Our research will contribute to the development of future guidelines regarding the specific frequency and duration of surveillance imaging of unruptured intracranial aneurysms.

    Learning Objectives: By the conclusion of this session, participants should be able to: 1) Identify the risk factor(s)for growth of unruptured intracranial aneurysms, 2) Identify patients which may warrant immediate occlusion or at least more frequent surveillance imaging, 3) Describe the annual risk of growth for unruptured intracranial aneurysms and the risk of de novo aneurysm formation.

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