الفهرس 
Overview of the Cerebrovascular DevelopmentOnly 14 pages are availabe for public view
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Abstract
Summary
Arteriovenous malformations are a complex tangle of abnormal arteries and veins linked by one or more fistulas. The fistulas allow high-flow, rapid arteriovenous shunting, thereby inducing arterial hypotension in vessels feeding the arteriovenous malformation and neighboring areas of the brain. Arteriovenous malformations have long been thought to arise from developmental derangements at the embryonic stages, at the fetal stage, or after birth. Their course cannot be easily predicted: they may remain static, grow, or even regress.
Arteriovenous malformations of the brain typically present before the age of 40 years and affect both sexes in nearly equal proportions. Rupture of these malformations accounts for only 2 percent of all strokes. Intracranial hemorrhage is the most common clinical presentation of arteriovenous malformation, with a reported frequency ranging from 30 to 82 percent.
The complex cerebrovascular anatomy of cerebral arteriovenous malformations makes them a challenge to treat, and the treatment itself carries significant risks. To evaluate the possible benefit of a risky treatment, one needs to understand the natural history and prognosis of the disease.
The goal for managing patients with intracranial arteriovenous malformations is to achieve a quality of life free from symptoms related to the AVM. In the absence of prospective trials or multicenter outcomes data, physicians are often forced to create subjective treatment plans based on local experience with some guidance from the literature. The aim of treatment is total obliteration of the malformation, because subtotal therapy does not confer protection from hemorrhage. Management strategies include single or combined therapy applying microsurgery, endovascular techniques, or radiosurgery. Each treatment modality has associated risks and benefits.
This clinical study presents an analysis of the qualities of the three tools used in treatment of cerebral AVMs. We tried to evaluate these modalities as regard procedural invasiveness, occlusion capacity, speed of efficacy, and long-term reliability. We analyzed the clinical and angioarchitectural outcomes as well as the complications resulting from management of 64 patients harboring cerebral AVMs.
Surgical excision, either as a single modality or combined with preoperative embolization, was the treatment option in 29 patients .Total nidal obliteraton was achieved in 90% of the surgically managed patients with a morbidity rate of 20.7%. AVM nidal size and the Spetzler-Martin grade were found to be predictors for the clinical outcome after surgical intervention. The rate of permanent nidal obliteration was found to be dependent on the Spetzler-Martin grade as well as the nidal configuration.
Radiosurgery was the treatment option chosen for 13 patients of those enrolled in our study. Seven patients exprienced preradiosurgical embolization. Total nidal obliteration was achieved in 69.2% of the radiosurgical group patients. Complications related to radiosurgical procedure occurred in 23.1% of the radiosurgical group patients; meanwhile no patient developed any new neurological deficit.
Embolization was chosen as a management modality in 22 patients. Onyx was the embolizing material in 10 patients of this group and NBCA was used in 12 patients. Total nidal obliteration was achieved in 33.3% of patients included in the endovascular group. On the other hand 66.7% of patients attained occlusion percentages ranging from 44% to less than 100%. A mortality rate of 4.5% was reported for endovascular intervention for cerebral AVMs. 4.5% of the endovascular patients also experienced neurological deterioration after endovascular intervention.
In general, surgical extirpation should be strongly considered as the primary mode of therapy for Spetzler-Martin grade I and II lesions. For patients with small lesions, where surgery offers some increased risk based on location or feeding vessel anatomy, radiosurgery should be strongly considered. For grade III lesions, a combined modality approach with embolization followed by surgery is often feasible. Surgical treatment only is often not recommended for grade IV and V lesions because it confers a high risk. Recommendations for endovascular management of AVMs can be divided into presurgical, preradiosurgical, or palliative management for focal neurological symptoms or uncontrolled seizures. In general, Spetzler-Martin grade II or III lesions may be embolized before surgery or radiosurgery. Embolization may be used in small arteriovenous malformations if there is an opportunity for cure (fistulous, single feeding artery) and there is a low morbidity risk.