Concept of arteriovenous malformation compartments and surgical management

Abstract

Cerebral AVMs are known to be a source of intracranial hemorrhages and epileptic seizures. Their natural history indicates approximately 15% mortality and 35% morbidity over a 15-year period. This significant mortality and morbidity mandates a need for satisfactory treatment of this entity, ideally by elimination of AVMs. Microsurgical resection, endovascular embolization and radiosurgery (irradiation) are the three effective modes of treatment currently available. However, no objective criteria have been established for which mode(s) of treatment should be selected for individual patients with AVMs. Considering the complexity of AVMs and variable conditions of individual patients, neurosurgeons, intravascular interventionalists and radiosurgeons must make their own decisions on how to treat each patient based on their experience. In practice, treatment of small AVMs in non-functional areas is favored equally by each of these specialists, while they tend to avoid treatment of large AVMs, particularly those in functional areas of the brain. The authors report the surgical intervention of large AVMs, including those located in functional areas of the hemisphere by special techniques. One can demonstrate AVM compartments by using angiography and with the aid of color Doppler ultrasonography, each compartment can be outlined and dissected individually until all the compartments are isolated without causing any damage to the surrounding brain and the entire AVM is rendered shrunken and then removed. The concept of compartmental treatment of AVMs may be applied in the future to radiosurgery and intravascular embolization of large AVMs.

Hemorrhagic Complications after Endovascular Treatment of Cerebral Arteriovenous Malformations

“…This highlights the importance of careful delivery of liquid embolic agent and emphasizes the need for thorough anatomic and hemodynamic knowledge of the AVM compartment and veins draining the nidus. 27 Venous deposition of the embolic agent can be difficult to see when a large volume has been injected or when multiple embolizations have already been performed because the attenuation of Onyx prevents visualization. Our study has some limitations.…”

Pathophysiology and Treatment of Brain AVMs*

“…There are dynamic changes at the arteriovenous junctions: the arterial wall normally resists the arterial pressure, and the veins with their much thinner wall are unable to resist the same pressure resulting in incremental dilatation from arterial pulsation [2]. The vessel wall of several arterial feeders is hypotrophic with a thin muscular layer, contrary to the angiographic appearance of a seemingly hypertrophic artery ( Figure 1 [3].…”

“…The shunting arterioles in circumferential feeding arteries constrict and reduce flow when the blood pressure is lowered to < 60 mm Hg. The nidus is composed of anomalous venous loops, and is almost always located subcortically with rare exceptions [2]. The flow from the arteries or arterioles within this nidus runs directly into the communicating venules representing the free communication system within the nidus.…”

Durable thrombosis in a rat model of arteriovenous malformation treated with radiosurgery and vascular targeting

“…Although endovascular therapy can be considered minimally invasive and in theory can obliterate flow, it is technically possible in only a few cases; its main use is as an adjunct to resection or radiosurgery. 16,41,59 Durable thrombosis in a rat model of arteriovenous malformation treated with radiosurgery and vascular targeting…”