Pediatric emergency medicine trisk 4004 4004

Arteriovenous Malformation Current Evidence Arteriovenous malformations (AVMs) are vascular abnormalities composed of a fistulous connection of arteries and veins without a normal intervening capillary bed In the cerebral hemispheres, they frequently occur as cone-shaped lesions with the apex of the cone reaching toward the ventricles Nearly all AVMs are thought to be congenital Supratentorial location is the most common (90%) The most common presentation of an AVM is intracerebral hemorrhage (ICH) AVMs are responsible for 30% to 50% of hemorrhagic strokes in children After ICH, seizure is the second most common presentation Other presentations of AVMs include headache and focal neurologic deficits which, including seizure, may be related to steal phenomena or other alterations in perfusion in the tissue adjacent to the AVM Size of AVM In a series of 168 patients followed after presentation without a prior hemorrhage, the size of the AVM was not found to be predictive of future hemorrhage However, other studies have found AVMs of small size to be at higher risk of hemorrhage AVMs and Aneurysms Prevalence of the association of AVMs with aneurysms varies from 2.7% to 22.7% This association seems to be correlated with a higher risk of hemorrhage Brown et al studied 91 patients with unruptured AVMs and found the risk of ICH in patients with coexisting aneurysm to be 7% at year compared with 3% among those with AVM alone At years, the risk persisted at 7% per year, while it decreased to 1.7% per year in those with an AVM not associated with aneurysms Diagnostic Imaging A CT scan may be used as an initial screening tool for patients presenting with neurologic sequelae related to unruptured or ruptured AVMs This study can be used quickly to determine location of the lesion, acute hemorrhage, hydrocephalus, or areas of encephalomalacia from previous surgery or rupture A nonenhanced CT may show irregular hyperdense areas frequently associated with calcifications in unruptured AVMs or acute hemorrhage with ruptured AVMs ( Fig 122.2 ) A contrastenhanced CT can demonstrate the nidus, feeding vessels, or dilated draining veins MRI is superior to CT scan in delineating details of the macro architecture of the AVM, except in the case of acute hemorrhage These