INTRODUCTION
Arteriovenous malformation (AVM) is an abnormal connection between arteries and veins, without normal anatomy and function which the capillary network should have.[1] This vascular anomaly can appear in any location in human body,[2] however, it is most frequently found in the brain in central nervous system and consequently called cerebral AVM or brain AVM, consisting of a nidus, arterial feeders, and draining veins.[3] Cerebral AVMs have been conventionally described as a congenital anomaly, although an increasing number of studies suggest that the etiology may be multifactorial.[4,5] Its incidence is 0.9 to 1.4 per 100,000 person-years,[3,6] and more than half of patients with cerebral AVM present with intracranial hemorrhage.[4,7] Spontaneous obliteration of unruptured AVMs is rare; it occurs in <1.5% of cerebral AVMs and only 7 cases have been reported so far.[8–10] This phenomenon, together with the formation and outcome of cerebral AVMs, remains barely understood. In this work, we presented such a case in which venous thrombosis and obliteration of an unruptured AVM were noted, and reviewed the relevant literature. The Ethics Committee of The Second Affiliated Hospital, College of Medicine, Zhejiang University approved this study and the patient provided written informed consent form. The ethical approval number was ZEYY20170803.