Abstract
Rupture of an intracranial aneurysm results in aneurysmal subarachnoid hemorrhage (SAH), a subtype of stroke with an incidence of 9 per 100,000 person-years and a case-fatality around 35%. In order to prevent SAH, patients with unruptured intracranial aneurysms can be treated by neurosurgical or endovascular interventions, but both treatment modalities
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carry a ~5-7% risk of unfavorable outcome due to treatment complications. Therefore, the risk of preventive aneurysm treatment needs to be balanced carefully against the risk of SAH due to aneurysm rupture. Current assessment of the risk of aneurysm rupture, which is mainly based on geographical region, aneurysm size and aneurysm location, is insufficient. This thesis focusses on the improvement of the assessment of aneurysm growth and rupture (Part I), aneurysm wall inflammation as underlying mechanism of aneurysm rupture (Part II), and outcome after preventive aneurysm treatment for a patient perspective (Part III). Chapter 2 is a systematic review and meta-analysis on the literature on patient- and aneurysm-specific risk factors for aneurysm growth. In chapter 3, we studied geometric and morphologic aneurysm-specific risk factors for aneurysm rupture, and found that aspect ratio and irregular shape are robust risk factors for aneurysms rupture, independent of aneurysm size, location, and patient-specific characteristics. In chapter 4 we investigated whether the PHASES score, a risk model for aneurysm rupture, also predicts for aneurysm growth. In chapter 5, we elaborated on the results of chapter 2 through 4, and developed a risk model to predict the risk of aneurysm growth in patients with unruptured intracranial aneurysms. In chapter 6, we investigated whether the seasonal variation in SAH incidence was associated with temperature or increased incidence of influenza-like-illness, a seasonal inflammatory disease. In chapter 7, we investigated the prevalence of gadolinium-enhancement on 3 Tesla MRI and its determinants in a prospectively collected cohort of patients with small unruptured intracranial aneurysms. In chapter 8, we focused on the outcome after preventive aneurysm treatment from a patient perspective. The studies in this thesis help us to provide guidance to patients and their treating clinicians in decisions on treatment and follow-up of unruptured intracranial aneurysms (Part I), it gives supportive evidence for the hypothesis of aneurysm wall inflammation as contributing factor in the pathogenesis of aneurysm rupture and a baseline cohort for future studies on aneurysm wall enhancement as promising biomarker for prediction of aneurysm wall instability (Part II), and a first impression of the losses of functioning, working capacity, and life satisfaction after preventive treatment of unruptured intracranial aneurysms (Part III).
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