Combined Endovascular and Microsurgical Management of Giant and Complex Unruptured Aneurysms

Francisco A. Ponce, M.D.; Felipe C. Albuquerque, M.D.; Cameron G. Mcdougall, M.D.; Patrick P. Han, M.D.; Joseph M. Zabramski, M.D.; Robert F. Spetzler, M.D.

Disclosures

Neurosurg Focus. 2004;17(5) 

In This Article

Discussion

Combined endovascular and surgical therapy has been practiced since 1987.[19] Early applications of endovascular therapy as a surgical adjunct included embolization of vascular lesions before resection.[4,18,20] This approach made it possible to obliterate extensive portions of vascular malformations and tumors and thus enhanced the feasibility of resection. Combined techniques have also been applied to the treatment of intracranial dural fistulas[6,12,17] and vascular occlusion.[11,16,21] The classic application of the combined technique is an extracranial-intracranial by pass combined with endovascular parent-vessel occlusion. First attempted in 1987, Serbinenko, et al.,[19] de scribed this technique in 1990 after treating nine patients with giant ICA aneurysms for whom direct clip occlusion was deemed to be associated with an unjustifiably high risk.

Early combined treatment strategies also included endovascular retrograde suction decompression of paraclinoid aneurysms to facilitate dissection and direct clip occlusion.[3] The use of balloon occlusion of the ICA before dissection of unruptured aneurysms allowed proximal artery control for temporary occlusion without requiring neck dissection for proximal control of the ICA.[15]

The overwhelmingly poor prognosis associated with untreated giant and complex aneurysms mandates aggressive treatment in which both microsurgical and endovascular techniques are used. In this series, combination therapy was performed safely and aneurysms were obliterated successfully in most cases. The use of such techniques significantly alters the natural history of these lesions.[5]

The combined endovascular and surgical treatment paradigms typically fall within one of four categories, as follows: 1) endovascular or surgical treatment after unsuccessful prior surgical or endovascular treatment, respectively; 2) endovascular treatment of the remote second aneurysm; 3) endovascular proximal parent artery control during surgery for clip occlusion/decompression; and 4) combined surgical and endovascular treatment for complex intracranial aneurysms (for example, microsurgical revascularization followed by endovascular parent-artery occlusion and flow-redirection techniques).

Barnett, et al.,[2] Lawton, et al.,[13] and Hacein-Bey, et al.,[7] published large contemporary series of patients treated with a combined modality. In this report, we reviewed only the subset of patients who received the aforementioned fourth treatment paradigm. Specifically, endovascular and surgical modalities were combined in the initial treatment plan. Broadly, these patients may be categorized in the following subgroups: 1) those with aneurysms involving the petrous, cavernous, or paraclinoid ICA that are not amenable to direct surgical clip occlusion and that require an STA-MCA bypass or a cervical carotid artery-MCA saphenous vein bypass graft followed by parent-vessel occlusion; 2) those with aneurysms in the posterior circulation that require an STA-SCA or OA-PCA bypass; and 3) those with complex aneurysms that cannot be eliminated from the circulation and that require flow-redirection techniques. In our series, the most common aneurysms for which a combined technique was required were those involving the cavernous ICA and PCA. Of the latter, most were dissecting aneurysms.

The technique for combining endovascular and surgical approaches to treat ICA aneurysms (Figure 1C) has been well described.[1,2,8,10,13,14,15] We treated 12 patients by using an STA-MCA bypass or cervical ICA-MCA saphenous vein bypass graft, and all had excellent outcomes.

Revascularization followed by parent-vessel occlusion was the modality used to treat PCA aneurysms. The PCA aneurysms were difficult to access and their morphology was complex; four were dissecting aneurysms, one was fusiform, and one was a giant lesion. These patients underwent OA-PCA microanastomosis followed by embolization and occlusion of the aneurysm and parent vessel (Figure 3C). One patient underwent an OA onlay instead of a bypass because of a poor-quality recipient artery.

The technical difficulty involved in the performance of an OA-PCA bypass may be greater than that for STA-MCA, as evidenced by the fact that homonymous hemianopia developed in four patients after PCA occlusion. Nevertheless, this deficit improved or resolved in two patients and was permanent in only one. The postoperative course in three patients treated for PCA aneurysms was complicated by EDH, underscoring the frequent but unfortunately necessary risk associated with heparinization during the endovascular treatment stage.

Flow-redirection techniques were used for aneurysms involving the BA and the ACAs. When an aneurysm cannot be removed from the circulation, the goal is to alter the hemodynamics at the lesion by changing the direction of blood flow.

The two patients with complex aneurysms involving the trunk of the BA were treated using flow reversal. The first procedure consisted of revascularization through an STA-SCA bypass, followed by a two-stage endovascular treatment. The second patient underwent procedures consisting of unilateral occlusion of the VA proximal to the PICA, followed by contralateral VA occlusion distal to the PICA. The goal in delaying occlusion of the second VA was to provide the graft with time to mature. Ultimately, one PICA depends on backflow from the BA, and this demand is thought to help prevent basilar thrombosis, thus maintaining flow from the bypass to the BA and the brainstem perforating vessels.

In both patients for whom this strategy was selected, postoperative EDHs developed, and neither individual survived long enough for the second endovascular procedure to be performed. One patient required a decompressive craniectomy and recovered from this procedure during his prolonged hospitalization. He died 3 months later of a posterior fossa stroke caused by BA thrombosis suffered on the day he was scheduled to undergo the second stage of endovascular treatment. One patient with a basilar apex aneurysm was treated with flow redirection en tailing surgical clip occlusion of the right P1 segment of the PCA, followed by stent placement in the distal BA and left PCA, followed in turn by stent-assisted coil embolization of the aneurysm (Figure 2D). This patient eventually died of an underlying malignancy, although her postoperative course was excellent.

Two patients underwent flow-reversal techniques for ACA aneurysms. One had an A2-A3 aneurysm and the other had an ACoA aneurysm. Both patients underwent A3-A3 bypass followed by endovascular occlusion of the aneurysm and feeding artery.

A combined technique also may be indicated when an aneurysm is amenable to endovascular treatment but the tortuosity of the feeding artery renders access to the lesion impossible. One patient underwent transposition of a tortuous ICA to straighten the segment containing the aneurysm. Stent placement in the parent vessel and coil occlusion of the aneurysm were then possible.

Comments

3090D553-9492-4563-8681-AD288FA52ACE

processing....