1F). This was embolized to a satisfactory occlusion. Subsequent surveillance of catheter cerebral angiographic images at 6 months and one year

have shown durable complete occlusion (Fig. 1G). Case Two A 55-year-old woman developed right carotid occlusive disease after Brefeldin A chemical structure subtotal resection and radiation of a right optic nerve glioma nearly 12 years prior. She was found to have an anterior communicating artery aneurysm that was clipped. Four months prior to presentation, she was found to have a 4 mm inferiorly directed anterior communicating artery aneurysm residual, (Fig. 2A) which was embolized with coils with a final result intentionally leaving some neck filling to minimize the risk of impairing flow to the contralateral hemisphere (Fig. 2B). Fig. 2 A. Oblique

left internal carotid angiography demonstrating a 4 mm inferiorly directed anterior communicating artery aneurysm with an occluded right internal carotid artery and significant bihemispheric opacification. B. Oblique left internal carotid angiography … Four months later, she developed a severe headache and was found to have subarachnoid hemorrhage in the basilar cisterns and interhemispheric fissure (Fig. 2C). Catheter angiography demonstrated the previously visualized embolized anterior communicating artery aneurysm to have increased in size to 15 mm in maximal diameter (Fig. 2D). Fortunately, embolization of the

aneurysm dome proceeded uneventfully (Fig. 2E) and she was discharged home with a favorable recovery and normal neurologic examination. DISCUSSION Hemodynamic stress is a well-known physiologic risk factor for cerebral aneurysm pathogenesis [6, 7, 8, 9, 10]. This has been further described as a sequential, repetitive reversal of flow within the dome of the aneurysm. Blood enters the cavity along the proximal wall and then emerges distally during systole. During diastole, the flow direction is reversed; these rapid changes in direction of blood flow continually stress the intima and neck of the cavity and may contribute to aneurysm formation and progression [11]. Histologically, a thinning of the tunica media can be observed, the critical component of the arterial wall that is responsible for compliance [12]. Entinostat Cervical carotid segment stenosis and/or occlusion, a relatively common finding [13] in about 3% of the general population, can increase this type of hemodynamic stress within the remaining collateral vessels. In the case of an ICA occlusion, cerebral perfusion pressure drops as regional blood flow is maintained via autoregulated vasodilation and the rerouting of blood through compensatory pathways. In a small series presented by van Everdingen et al. patients with symptomatic unilateral ICA occlusion had increased contralateral flow in the internal carotid and basilar artery.