Arteriovenous Malformations

Arteriovenous malformations commonly present with intracerebral hemorrhage that may be intraparenchymal, intraventricular, subarachnoid or subdural. Consequently, a head CT scan is often the initial radiographic investigation for an AVM and, generally, is the best study to delineate the presence and location of acute intracerebral blood (Fig. 20.2a). In the absence of hemorrhage, an AVM nidus appears slightly hyperdense, sparsely calcified and wedge-shaped on a non-contrast head CT. The apex of a wedge-shaped AVM is directed towards the ventricular system. The arterial feeders, nidal vessels and dilated draining veins are seen on head CT scans after administration of intravenous contrast. MRI is useful in defining the exact anatomic location and size of an AVM. On MRI, the AVM nidus appears as a prominent nest of flow voids within the brain parenchyma (Figs 20.1a, b, c and 20.2b). The large, dilated draining veins adjacent to the nidus are generally well seen. Hemosiderin deposition occurs after AVM hemorrhage; this hemosiderin deposition causes low signal changes on T2-weighted and gradient-echo MRI images and is diagnostic of old hemorrhage. Hemosiderin is not seen on CT scans. Cerebral angiography is necessary for treatment planning. An angiogram fully defines the AVM's angioarchitecture, including its location and size, the number and origin of its arterial feeders, nidal anatomy, direction of venous outflow and the presence of AVM-associated aneurysms (Figs 20.1d-g, 20.2c, d and 20.3a, b). We have not found MRA studies to be useful in treatment planning for AVMs.

Cure Your Yeast Infection For Good

Cure Your Yeast Infection For Good

The term vaginitis is one that is applied to any inflammation or infection of the vagina, and there are many different conditions that are categorized together under this ‘broad’ heading, including bacterial vaginosis, trichomoniasis and non-infectious vaginitis.

Get My Free Ebook


Post a comment