BACKGROUND AND AIM Spontaneous partial or complete thrombosis of saccular unruptured intracranial aneurysm (UIAs) is a known occurrence in giant aneurysms. However, spontaneous complete thrombosis of non-giant aneurysms is a rare event in the natural history of UIAs. The aim of this paper is to report on the cases from literature of complete spontaneous thrombosis with a view to identify possible factors associated with this phenomenon. MATERIAL AND METHODS We performed a systematic review of the current literature on spontaneous complete thrombosis of saccular, non-giant, unruptured UIAs, including a case that we treated at our institution. We analysed the possible risk factors for thrombosis, association with ischemic events, rupture and recanalization. We reviewed the possible management's strategies for this group of patients described in literature to date. RESULTS We identified 26 patients for a total of 27 thrombosed aneurysms from the literature review (including our case). Thrombosis was prevalent in women, in the anterior circulation and in larger aneurysms. Endovascular events in the parent artery, either spontaneous or iatrogenic, were associated with spontaneous thrombosis in 4 cases. In 47 % of cases an antiplatelet treatment (AP) was introduced. Rupture and recanalization of the aneurysm were observed in 14 % and 33 % respectively. A larger size was the only factor statistically associated with rupture (P = 0041). AP was not statistically associated with recanalization or rupture of the aneurysm. CONCLUSION Complete spontaneous thrombosis is not a curative event. Its natural history is associated with recanalization, rupture and ischemic stroke. Conservative treatment with a clinical-radiological follow up and treatment with AP is a safe option for small aneurysms. Definitive aneurysmal exclusion should be considered in medium and large aneurysms due to the significant risks associated with untreated aneurysms.

中文翻译：

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未破裂非巨大颅内动脉瘤的完全自发性血栓形成：病例报告和系统评价

背景和目的囊状未破裂颅内动脉瘤（UIA）的自发性部分或完全血栓形成是巨大动脉瘤中的一种已知事件。然而，非巨大动脉瘤的自发性完全血栓形成是 UIA 自然病程中的罕见事件。本文的目的是报告完全自发性血栓形成文献中的病例，以确定与这种现象相关的可能因素。材料和方法 我们对当前关于囊状、非巨大、未破裂 UIAs 自发性完全血栓形成的文献进行了系统回顾，其中包括我们在我们机构治疗的一个病例。我们分析了血栓形成的可能危险因素、与缺血事件的关联、破裂和再通。我们审查了可能的管理 迄今为止文献中描述的针对这组患者的策略。结果 我们从文献回顾（包括我们的病例）中确定了 26 名患者，共 27 个血栓形成的动脉瘤。血栓形成在女性、前循环和较大的动脉瘤中普遍存在。4 例自发性或医源性载瘤动脉血管内事件与自发性血栓形成有关。在 47% 的病例中引入了抗血小板治疗 (AP)。分别在 14% 和 33% 中观察到动脉瘤破裂和再通。较大的尺寸是与破裂统计相关的唯一因素（P = 0041）。AP 与动脉瘤再通或破裂无统计学相关性。结论 完全自发性血栓形成不是治愈性事件。它的自然病程与再通有关，破裂和缺血性中风。带有临床放射学随访和 AP 治疗的保守治疗是小动脉瘤的安全选择。由于与未经治疗的动脉瘤相关的重大风险，中型和大型动脉瘤应考虑明确排除动脉瘤。