Arteriovenous malformations are not always congenital, there are also acquired, but the probability of acquired is particularly small. Arteriovenous malformations belong to a large category of cerebrovascular malformations. Normal blood circulation should transition from the arteries to the capillaries and then to the veins, but in patients with arteriovenous malformations the arteries drain directly into the veins, lacking the transition from the capillary layer, which can make the patient likely to develop epilepsy, headaches, intracranial hemorrhage, neurological dysfunction and other manifestations. Congenital arteriovenous malformations are mostly due to abnormal vascular lesions that occur during embryonic development, causing blood to drain directly from the arteries to the veins; acquired ones are mostly due to inflammation, trauma, and other causes of arteriovenous malformations, but the probability is smaller. Arteriovenous malformations do not present with symptoms at first, but as the patient ages, headaches, bleeding in the brain, and impaired consciousness usually develop after the age of 20. If the patient experiences these symptoms, it is recommended that the patient seek medical attention and treatment.