**4. Conclusion**

262 Aneurysm

occurred.

intracranial bypass should be contemplated.

**3.4. Coil embolisation and stent placement** 

**3.3. Parent vessel occlusion** 

One of the treatment options available for patients with internal carotid or vertebral artery aneurysms is parent vessel occlusion, either surgical or endovascular. The goal of parent vessel occlusion for the treatment of fusiform aneurysms is intra-aneurysmal thrombosis and involution of the aneurysm. Endovascular occlusion can be achieved with detachable balloons or coils or with a combination of the two. Studies reporting patient outcomes after parent vessel occlusion for treatment of fusiform aneurysms of the vertebrobasilar circulation have been limited. A few series have reported the results of parent vessel occlusion in the posterior circulation, although not exclusively for intracranial fusiform aneurysms. In one study the long-term outcomes for 21 patients with unclippable posterior circulation aneurysms treated with either unilateral or bilateral parent vessel occlusion of the vertebral artery, with a mean follow-up of 2 years (range, 6 months to 6 years) were examined [47]. Six of the patients had fusiform aneurysms, and the remaining 5 had aneurysms that were of saccular morphology. All occlusions in this series were performed by using latex balloons. Thirteen (61.9%) of 21 patients achieved good outcomes, including angiographic cure and clinical improvement. Twenty-eight and six-tenths percent of the patients had partial thrombosis of their aneurysm. One death and one treatment failure

Occlusion of the internal carotid artery may lead to severe cerebrovascular events and therefore a balloon occlusion test should be performed in advance; if a temporary occlusion test is successful, trapping or parent artery occlusion is an option. However, it has been shown that 5–22% of patients passing the balloon occlusion test develop ischemic complications, including cerebral infarct, while some reports have revealed cerebral aneurysm formation after permanent carotid occlusion [48,49]. The placement of detachable balloons in the ICA above and below the false aneurysm can completely eliminate blood flow. Disadvantages with this endovascular approach include the possibility of embolic cerebrovascular accidents. If the patient cannot tolerate the occlusion test, an extracranial-to-

Another treatment option in the management of aneurysms represents stent placement with or without coil embolisation and coil embolisation without stent placement. Findings of experimental studies have shown that a metallic stent, bridging the aneurysmal neck, may alter the flow pattern within the aneurysm, promoting thrombus formation and aneurysmal occlusion [50,51]. Although immediate aneurysmal occlusion can be seen after single stent placement for treatment of extracranial pseudoaneurysms, in some cases, 3–6 months or longer may pass before occlusion occurs. To achieve faster complete aneurysmal occlusion, the combination of stents and detachable coils has been suggested for extracranial, as well as intracranial aneurysms [2,52,53] and the combination is currently considered an alternative to single stent placement or other techniques such as the remodeling technique or parent vessel occlusion. Lanzino et al [52] reported 10 cases managed with stent-supported coil

In conclusion, endovascular treatment of vertebral and carotid artery aneurysms with covered stents is very promising, safe and feasible treatment option. So called flow diverting devices despite their "slow mode" of action, but according to their special features (as is high flexibility and very low profile), seems to be very effective tool in endovascular treatment of carotid and vertebral artery aneurysms. On the other hand, covered stents with for example a novel pericardium covered stent, allow complete occlusion of the aneurysm, fistula or dissection in one action. This approach in the treatment of aneurysms seems to be very promising. Therapeutic decision making in the treatment of vertebral and carotid artery aneurysms must balance endovascular or surgical morbidity and mortality rates with the risk of hemorrhage and other considerations on an individual basis. Evolving technologies move towards increased covered stents flexibility with pushing down their profiles. This evolution followed with future studies of these advanced endovascular approaches will probably increase the role of covered stents in the field of endovascular treatment of vertebral and carotid artery aneurysms in the future. More detailed clinical studies will need to be conducted to confirm the overall performance and long-term effect of covered stents in the treatment of internal carotid and vertebral artery aneurysms.
