AVM aneurysms

Ideally, there should be no venous enhancement. Nevertheless, except for specific indications such as cavernous sinus aneurysm and arteriovenous malformation (AVM) assessment, this is seldom clinically limiting. Z-direction coverage, in-plane and longimdinal resolution, and signal-to-noise ratio should be maximized, while radiation dose, total amount of contrast administered, and acquisition slice thickness should be minimized. Our routine stroke CTA protocol for 16- or 64-slice MDCT scanners covers from the great vessel origins at the aortic arch to the cranial vertex. 

Reconstruct CTA to identify aneurysm or AVM in hemorrhagic stroke, major vessel occlusion in ischemic stroke... 

The procedure for Onyx administration in an aneurysm is similar to the plug and push technique described for AVM embolization, but with the additional consideration of inflation and deflation of the balloon during the procedure such that blood flow in the parent artery is not restricted for an extended period of time. Overall, this may tend to increase procedure times when embolizing aneurysms with Onyx as opposed to coil embolization. 

Embolic materials for both intracranial AVMs and aneurysms have come a long way since the first endovascular embolization procedure was carried out. Much advancement to this branch of neurosurgery came about because of an emphasis on development of equipment that was better suited to endovascular techniques. Some of these inventions include flow-directed microcatheters, endovascular balloons, and re-designed stents. Owing to a greater capacity to perform endovascular techniques with suitable equipment, the development of better embolic materials has followed. Now, there are a variety of techniques and materials that endovascular neurosurgeons have at their disposal, all of which provide a variety of benefits, yet have considerable drawbacks. Efforts are always being made to improve current materials and techniques, as well as to... 

In the series of Cunha e Sa et al. (1992) the site of rupture was the aneurysm in 46% of cases, the AVM in 33% of cases, and undetermined in 21% of cases. In other series (Batjer et al. 1986 Piotin et al. 2001), the source of hemorrhage in patients harboring brain AVMs and associated aneurysms was identified as an aneurysm in approximately 80% of cases. 

A higher percentage of multiple aneurysms has been reported in the population of patients with brain AVMs (Batjer et al. 1986 Brown et al. 1990 Cunha e Sa et al. 1992 Thompson et al. 1998), but this feature seems not to be associated with a higher risk of hemorrhage (Piotin et al. 2001). 

On the basis of retrospective analysis, the rupture of brain AVMs is estimated to be less severe than that of intracranial aneurysms, with mortality between 10% and 15% and an overall morbidity of less than 50% (The Arteriovenous Malformation Study Group 1999). Hemorrhages of brain AVMs are subarachnoidal (30%), parenchymal (23%), intraventricular (16%), and in combined locations in 31% of cases (Hartmann et al. 1998). Parenchymal hemorrhages were most likely to result in a neurological deficit (52%). Overall, in the series of Hartmann et al. (1998), 47% of patients... 

In fact, as was shown by Hillman (2001), the rupture of an AVM is as devastating as that of an aneurysm. While aneurysm rupture is more lethal than AVM rupture (21% vs 9%), a good outcome is obtained less frequently in AVM than in aneurysm ruptures (49% vs 56%), due to the high incidence of parenchymal hematoma. 

Because there is no consensus concerning treatment of AVM and associated aneurysms, we propose the following practical strategy ... 

In cases where the hemorrhage is clearly due to AVM rupture the treatment is aimed primarily at the AVM. The first embolization procedure maybe performed after the acute phase, as for ruptured brain AVM not associated with aneurysms. 

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