Surgical management of Cerebral Aneurysms by Frederick Vincent No disclosure that would be a potential conflict of interest with this presentation Plan: .Epidemiology .Etiology .Histology of intracranial arteries .Location .Presentation of aneurysms .Conditions associated with aneurysms .Classic saccular aneurysm: pathogenesis, risk factors, vessel wall pathology, histopathology .Surgical approaches to aneurysms .Surgical technique .Cases of brain aneurysm Epidemiology Difficult to estimate Autopsy prevalence: 0.2 – 7.9% , it depends Prevalence 5% Ratio of ruptured: unruptured 5:3 to 5:6 (rough estimate is 1:1) 50% of these aneurysms rupture Only 2% present during childhood Etiology .Congenital predisposition (medial gap/muscular layer) .Atherosclerotic or hypertensive .Embolic: as in atrial myxoma .Infectious (mycotic aneurysm) .Traumatic .Associated with other conditions Histology of intracranial arteries • Intima (17%), media (52%) and adventitia (31%) • Endothelium and subendothelial connective tissue • Internal elastic lamina (mechanical strength) separates the I and M • M consists of closely packed layers of smooth muscle cells surrounded by collagen and elastin fibers • No external elastic lamina between M and Ad • Ad is very thin • Lower wall:lumen ratio • Mean wall thickness 0.6 mm in the Basilar and 0.5 mm MCA • Intradural arteries are surrounded by CSF remain in this state after entering the brain parenchyma (perivascular space/Virchow-Robin spaces) • Ensheathed by “glia limitans” -> specialized layer of astrocytes Location • Apex of branch points which is the site of max hemodynamic stress • More peripheral do occur associated mycotic aneurysm or trauma • Fusiform aneurysms more common in the VertBasilar system • Dissecting aneurysm (categorized with arterial dissection) • Saccular aneurysm locations • 85-95% in the carotid system: AcoA 30% p-com 25% MCA 20% • 5-15% in the posterior ciculation: 10% basilar tip 5% vertebral • 20-30% have multiple aneurysms Presentation • Rupture • SAH • Intracerebral hemorrhage 20-40% • IVH 13-28% • Subdural hematoma 2-5%