This procedure involves using a catheter, threaded through an artery up to the head, to deliver a contrast agent into the AVM. As the contrast agent flows through the AVM structure, a sequence of X-ray images are obtained. Grading
Spetzler-Martin (SM) Grade
A common method of grading cerebral AVMs is the Spetzler-Martin (SM) grade. This system was designed to assess the patients risk of neurological deficit after open surgical resection (surgical morbidity), based on characteristics of the AVM itself. Based on this system, AVMs may be classified as grades 1 - 5. This system was not intended to characterize risk of hemorrhage. "Eloquent" is defined as areas within the brain that, if removed will result in loss of sensory processing or linguistic ability, minor paralysis, or paralysis. These include the basal ganglia, language cortices, sensorimotor regions, and white matter tracts. Importantly, eloquent areas are often defined differently across studies where deep cerebellar nuclei, cerebral peduncles, thalamus, hypothalamus, internal capsule, brainstem, and the visual cortex could be included. The risk of post-surgical neurological deficit (difficulty with language, motor weakness, vision loss) increases with increasing Spetzler-Martin grade. Supplemented Spetzler-Martin (SM-supp, Lawton-Young) Grade
A limitation of the Spetzler-Martin Grading system is that it does not include the following factors: Patient age, hemorrhage, diffuseness of nidus, and arterial supply. In 2010 a new supplemented Spetzler-Martin system (SM-supp, Lawton-Young) was devised adding these variables to the SM system. Under this new system AVMs are classified from grades 1 - 10. It has since been determined to have greater predictive accuracy that Spetzler-Martin grades alone.
Treatment
Treatment depends on the location and size of the AVM and whether there is bleeding or not.The treatment in the case of sudden bleeding is focused on restoration of vital function.Medical management
Anticonvulsant medications such as phenytoin are often used to control seizure; medications or procedures may be employed to relieve intracranial pressure. Eventually, curative treatment may be required to prevent recurrent hemorrhage. However, any type of intervention may also carry a risk of creating a neurological deficit.Preventive treatment of as yet unruptured brain AVMs has been controversial, as several studies suggested favorable long-term outcome for unruptured AVM patients not undergoing intervention. The NIH-funded longitudinal ARUBA study ("A Randomized trial of Unruptured Brain AVMs) compares the risk of stroke and death in patients with preventive AVM eradication versus those followed without intervention. Interim results suggest that fewer strokes occur as long as patients with unruptured AVM do not undergo intervention. Because of the higher than expected event rate in the interventional arm of the ARUBA study, NIH/NINDS stopped patient enrollment in April 2013, while continuing to follow all participants to determine whether the difference in stroke and death in the two arms changes over time.Surgical management
Surgical elimination of the blood vessels involved is the preferred curative treatment for many types of AVM. Surgery is performed by a neurosurgeon who temporarily removes part of the skull (craniotomy), separates the AVM from surrounding brain tissue, and resects the abnormal vessels.