Cognition and Functional Connectivity After Elective Treatment of Brain Aneurysms

The aim of this proposal is to investigate the effects of uneventful microsurgical and endovascular treatment of unruptured saccular non-giant anterior communicating artery [ACoA] aneurysms on resting state functional connectivity levels of higher order cognitive networks and to correlate the connectivity levels of these networks with neuropsychological performance and functional outcome. The investigators' hypothesis is that the functional connectivity of various cognition networks, i.e. cognitive control network, emotion control of cognitive networks, and working memory networks, as assessed by resting state functional magnetic resonance imaging [rsfMRI], can be impaired after uneventful microsurgical and endovascular treatment of unruptured ACoA aneurysms and can be correlated with neuropsychological performance. The investigators propose to investigate 38 patients harboring unruptured ACoA aneurysms and 19 healthy controls over a 36 (until 48) months period. Patients and healthy controls will undergo baseline structural MRI, task fMRI, rsfMRI, and baseline neuropsychological examinations prior as well as 2 months after either microsurgical or endovascular aneurysm treatment or baseline examinations, respectively. Furthermore all subjects will undergo additional neuropsychological examinations 12 months after baseline examination or long-term recovery from microsurgical and endovascular treatment, respectively. The research question is of substantial importance for this patient population, since it is currently incompletely understood how the minor structural brain tissue damages seen after both treatment methods of unruptured ACoA aneurysms translate into the observed neuropsychological deficits - which are often subtle and transient in nature but still insufficiently explained on grounds of morphology and structural connectivity alone. The sensitivity of rsfMRI to depict the functional communication of spatially remote brain regions presents a novel opportunity to investigate these deficits on a whole brain scale by mapping resting state functional connectivity in higher order cognition networks that are thought to be endangered by events related to both microsurgery and embolization. Correlating these data seems promising for several reasons. First, functional connectivity analysis could be correlated with the neuropsychological impairment in various neuropsychiatric disorders and in ischemic stroke. Ischemic damage to the territories supplied by ACoA perforating arteries is involved in many cases of postoperative neuropsychological impairment after ACoA aneurysm treatment. Second, neuropsychological evaluations have become increasingly incorporated into the standard of care in the postoperative follow-up of cerebral aneurysm patients. RsfMRI could serve as a novel adjunct to neuropsychological outcome assessment. Third, the results could add relevant information to the general perception of the role of frontal lobe and forebrain damage in the pathophysiology of neurocognitive impairment. This could have an impact on neurorehabilitation programs to improve neurocognitive outcome and quality of life in this patient population. Forth, the correlation of validated neuropsychological tests with the functional connectivity rsfMRI data would further enhance the role of rsfMRI in neuroscience and its clinical use.