Treatment of Cerebral Arteriovenous Malformations Internal Treatment The treatment plan for AVMs must be based on the risk of subsequent cerebral hemorrhage, which is determined by each patient’s demographics, past history, and angiographic features. AVMs with a history of hemorrhage, small size, and relatively high pressure in the deep drainage and supply arteries have a higher likelihood of hemorrhage. Treatment is recommended for young AVM patients with one or more high-risk features, while older patients or those without high-risk features are best managed symptomatically only. In the latter case, only anticonvulsants are recommended for seizure control and moderate analgesics for headache relief, if necessary. 1. anticonvulsants Depending on the type of epilepsy, it can be brought under control by applying different conventional anticonvulsant treatments. Most patients can be well controlled with phenytoin, carbamazepine, valproic acid or lamotrigine. Treatment of headache Both nonspecific headache and migraine can be treated with conventional analgesics. 5-hydroxytryptamine agonists are not particularly contraindicated unless focal neurological deficits are present during migraine attacks. Surgical treatment of AVM includes surgical resection, endovascular embolization, and focal radiation therapy – either alone or in combination. 1. Surgical resection: Surgical resection has long been the primary radical treatment, and is most effective for smaller, easily accessible lesions. Depending on the location of AVM, the lesion can be approached via different pathways such as the convex surface of the brain, skull base or ventricular system during craniotomy. The lesion is removed after freeing and ligating the blood supplying arteries and draining veins. Surgical clamping of the aneurysm may also be performed. Postoperative angiography is routinely performed to determine if there are residual lesions; however, cases of AVM recurrence several years later without residual angiography after AVM resection have been reported. 2. Endovascular embolization: Super-selective endovascular treatment consists of introducing substances that can induce thrombosis, such as fast-acting acrylate gels, spring coils that can induce thrombosis, sclerosing agents, or small balloons, into the AVM lesion. The purpose of embolization is to stop the shunting of high velocity blood flow from the high pressure artery to the venous system. Embolization is more commonly used as a pre-treatment for surgical or radiosurgical treatment rather than as a radical treatment. Continuous embolization therapy can gradually reduce the AVM to a fraction of its original size, and the reduction in AVM volume and the presence of embolic material within the AVM can make surgical and radiosurgical treatment safer and more precise. Even if the embolization treatment can not completely make the lesion disappear, it can relieve the neurological symptoms caused by the large AVM. Radiosurgery: Radiosurgery is suitable for AVMs ≤3 cm in diameter. proton beam, linear gas pedal or gamma knife can release high energy rays to AVMs with minimal effect on surrounding normal brain tissue, and a single dose is usually sufficient. Proton beam irradiation can sometimes be used to treat larger lesions. It is generally accepted that radiation therapy achieves its therapeutic goal by inducing thrombosis. It is attractive because of its non-invasive nature. After treatment, the white matter of the brain surrounding the AVM often shows a high signal shadow on MRI, and when treated to a greater extent, a significant occupying effect due to edema is seen. It may take 1 to 3 years for radiosurgery to fully thrombose the AVM, so patients remain at risk of bleeding during treatment.