German Clinical Trials Register

Acronym/abbreviation of the study

MICRON

URL of the study

http://www.micron.study/

Brief summary in lay language

About 2-3% of the average adult population are the carriers of intracranial aneurysms. In case of aneurysm rupture, subarachnoid hemorrhage occurs, often with very severe disease progression and high mortality. Therefore, the study of the natural history of intracranial aneurysms with identifying relevant risk factors for growth, progression, and rupture is of great clinical importance. Previous histological studies of intracranial aneurysms have identified inflammation on the vessel wall as a driving force of intracranial aneurysms. However, with small numbers of tissue samples and inadequate history collection, the potential of histological studies could not be fully exploited. This study aims to initiate a multi-center histological aneurysm registry in which the clinical data on the included patients will be collected with a standardized survey form, and the tissue samples collected intraoperatively will be examined at the study center using various microscopic, immunohistochemical, and molecular genetic tests to clarify the influence of patient history on the morphological, histological, and molecular genetic characteristics of intracranial aneurysms.

Brief summary in scientific language

Intracranial aneurysms are a rare disease of cerebral vessels, present in about 2-3% of the average adult population. Due to their small size (average diameter about 7 mm), intracranial aneurysms remain asymptomatic for some time. Most intracranial aneurysms even remain lifelong without any clinical relevance for affected patients. However, in case of aneurysm rupture, a severe form of cerebral hemorrhagic stroke, subarachnoid hemorrhage, occurs. With this disease, despite maximal therapy and the advances in neuro-intensive medical treatment, patients suffer from severe disease progression with long-term morbidity of over 50% and hospital mortality of 25-30%. Interventional treatment of intracranial aneurysms by endovascular coiling or microsurgical clipping is well established and feasible, but carries treatment-related risks of up to 10%. Therefore, the study of risk factors for the development, growth, and rupture of intracranial aneurysms is of major clinical importance. So far, some risk factors have been identified, such as female gender, arterial hypertension, smoking, drug, and alcohol consumption. Much has been speculated about the role of other diseases in aneurysm development, but the data are very sparse. Moreover, it is unclear whether daily medications also influence the natural history of intracranial aneurysms. In this regard, there are some studies with abdominal aortic aneurysms, where significant correlations were found in some cases, which may serve as a basis for drug risk control for aneurysm growth and rupture in the future. To verify various clinical parameters as aneurysm-relevant risk factors, correlation of these reports with the immediate changes in the aneurysm wall is essential. To date, some histologic studies have been performed on the routinely collected tissue samples from the aneurysm wall, with few definitive conclusions overall due to the relatively small cohort sizes and the small number of markers examined, as demonstrated in a recent meta-analysis. To date, the reliable data indicate a significant role for local inflammation, intraluminal thrombosis, and oxidative stress in local shear-induced injury to the vessel wall. To what extent the well-known and suspected risk factors influence the pathophysiological processes occurring in the aneurysm wall and which of these cascades could be modulated by pharmacokinetic action is currently totally unclear. To adequately investigate the whole relationship between patient-specific clinical risk factors and aneurysm wall changes, considering the experience from the previous smaller retrospective studies (limited to about 20 patients on average), a prospective data collection including a representative number of patient tissue samples (about 300) is required. Nowadays, the primary treatment choice for intracranial aneurysms is endovascular coiling. Since such samples are only collected in microsurgical clipping, a temporally foreseeable implementation of such a project is only possible in the context of a collaborative project between several treating centers. Therefore, the research project is intended as a multi-center prospective histological aneurysm registry. For three years, tissue samples from Germany's participating major neurovascular centers, which treat intracranial aneurysms by microsurgical clipping and routinely take tissue samples intraoperatively from the clipped aneurysms, will be collected, processed, and examined centrally at the Essen Study Center.