Subsequent recanalization of an angiographically proven obliterated AVM has not occurred in our experience. The occlusion of the vessels is not a thrombotic process but rather the culmination of concentric narrowing of the vessel by an expanding vessel wall. Expansion of the extracellular matrix and cellular degeneration define the final stage prior to luminal obliteration. The most important changes are seen later in the intima with the appearance of loosely organized spindle cells (myofibroblasts) and an extracellular matrix containing collagen type IV, not seen in the intima of untreated vessels. The earliest change is damage to the endothelium with swelling of the endothelial cells and subsequent denution or separation of the endothelium from the underlying vessel wall. The pathological changes in AVM’s treated with the Gamma Knife have been described by several authors. The introduction of the Gamma Knife rekindled interest in the treatment of AVM’s with radiation. In this early period, Johnson was the only one to report reasonable results with a 45% angiographic obliteration.
OBLITERATION MEANS SERIES
This early success was overshadowed by numerous series of failures. At re-operation five years later only an obliterated avascular mass was discovered. He then treated the patient with fractionated radiation. During craniotomy for an AVM he had to interrupt surgery due to major hemorrhage from the lesion. The effects of ionizing radiation and a role in the management of AVM’s was first reported in 1928 by Cushing. Complete radiographic obliteration can be achieved after appropriate Gamma surgery. The minimal clinical and only moderate changes in the normal cerebral vasculature after high doses of gamma radiation is in sharp contrast to the response of the vessels of an AVM. UVA Child Development & Rehabilitation Center.Translational Health Research Institute of Virginia.Institute of Law, Psychiatry & Public Policy.Child Health Research Center (Pediatrics).Thaler Center for AIDS & Human Retrovirus Research Center for Immunity, Inflammation & Regenerative Medicine.Center for Behavioral Health & Technology.Molecular Physiology & Biological Physics.Microbiology, Immunology, & Cancer Biology (MIC).
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