Temporary and permanent occlusion of cervical and cerebral arteries

Bypass Surgery for Complex Intracranial Aneurysms: 15 Years of Experience at a Single Institution and Review of Pertinent Literature

BACKGROUND

Bypass surgery is a treatment option for complex intracranial aneurysms.

OBJECTIVE

To determine the utility of bypass surgery for the treatment of complex intracranial aneurysms and to review the literature on this topic.

METHODS

Sixty-two patients were included in this retrospective study. Unruptured aneurysms were dominant (80.6%), and the internal carotid artery was the most common location of the aneurysm (56.4%), followed by the middle cerebral artery (21.0%). The mean maximal diameter of the aneurysms was 20.5 ± 11.4 mm. The clinical and angiographic states were evaluated preoperatively, immediately after surgery (within 3 days) and at the last follow-up. The mean angiographic and clinical follow-up duration was 34.2 ± 38.9 and 46.5 ± 42.5 months, respectively.

RESULTS

Sixty-one patients (98.3%) underwent extracranial–intracranial bypass, and 1 underwent intracranial–intracranial bypass. At the last follow-up angiography, 58 aneurysms (93.5%) were completely obliterated and 4 were incompletely obliterated, with a graft patency of 90.3%. Surgical mortality was 0 and permanent morbidity was 8.1%. A good clinical outcome (Karnofsky Performance Scale ≥ 70 and modified Rankin Scale score ≤ 2) was achieved in 91.9% of patients (n = 57).

CONCLUSION

With a proper selection of bypass type, bypass-associated treatment can be a good alternative for patients with complex intracranial aneurysms when conventional microsurgical clipping or endovascular intervention is not feasible.

Bypass or not? Adjustment of surgical strategies according to motor evoked potential changes in large middle cerebral artery aneurysm surgery

OBJECTIVE

To report the use of neuroelectrophysiologic monitoring to alter the course in aneurysm surgery to minimize postoperative infarction and bypass-related adverse events.

METHODS

Two patients with large middle cerebral artery (MCA) aneurysms were admitted to the authors' hospital. Direct clipping seemed to be difficult, and postoperative paralysis was not rare in the authors' experience owing to prolonged temporal occlusion of the parent artery. Balloon test occlusion (BTO) was positive in one patient, who developed paralysis and aphasia 3 minutes after balloon occlusion of the feeding M1 artery. A bypass procedure seemed to be inevitable in both patients. Motor evoked potentials (MEPs) and sensory evoked potentials (SEPs) were used for monitoring during the operation.

RESULTS

For the patient with a positive BTO result, MEP waves did not change until 17 minutes after temporary clip placement. The aneurysm was clipped, and the occlusion time was 24 minutes. MEP waves recovered quickly after reperfusion. In the other patient, there were early changes in MEP waves after temporary clipping. After bypass construction from the temporal artery to the inferior M2 trunk, the time window of safe occlusion was prolonged to 7-8 minutes. Both the aneurysm and the bypassed branch were obliterated, and the clip reconstruction was done to preserve the flow from M1 to the superior M2 trunk. Permanent postoperative disability did not occur in either patient.

CONCLUSIONS

Intraoperative physiologic monitoring is a complementary method to preoperative BTO to evaluate the window of safe occlusion with high reliability.

Perioperative and intraoperative maneuvers to optimize surgical outcomes in skull base surgery

There are many approaches to obtaining a workable endoscopic surgical field in sinus surgery. With extended sinus and transdural endoscopic surgery, a more rigid approach must be taken. There are 3 main factors that invariably lead to poor surgical outcomes in endoscopic sinus and skull base surgery: bleeding, inadequate access, and unidentified anatomic anomalies. Bleeding is arguably the most common reason for incomplete resection. An understanding of microvascular and macrovascular bleeding allows a more structured approach to improve the surgical field in extended endoscopic surgery. The endoscopic surgeon should always be comfortable in performing the same procedure as an open operation. However, converting or abandoning an endoscopic procedure should rarely occur because much of this decision making should take place preoperatively. Along with poor hemostasis, inadequate access is an important cause of poor outcome. Evaluation of the anatomy involved by pathology but also the anatomy that must be removed to allow adequate exposure is important. This article reviews the current techniques used to ensure optimal surgical conditions and outcomes.

Vertebral artery-posterior inferior cerebellar artery bypass using a radial artery graft for hemorrhagic dissecting vertebral artery aneurysms: surgical technique and report of 2 cases

Endovascular occlusion of hemorrhagic dissecting aneurysms of the vertebral artery (VA) is not possible when the posterior inferior cerebellar artery (PICA) originates from the dissecting aneurysm or when the contralateral VA provides inadequate collateral blood flow to the distal basilar circulation. The authors introduce a VA-PICA bypass with radial artery interposition graft and aneurysm trapping as an alternative approach and describe 2 cases in which this bypass was used to treat hemorrhagic dissecting VA aneurysms. The VA-PICA bypass is performed via a standard far lateral approach. An end-to-side anastomosis between the radial artery graft and the PICA at the level of the caudal loop is performed first, and an end-to-side anastomosis is performed between the V(3) segment and the proximal end of the radial artery graft. A 56-year-old woman harbored a hemorrhagic dissecting VA aneurysm incorporating the origin of the PICA. Endovascular treatment failed, with aneurysm refilling on follow-up angiography. A 65-year-old man had a hemorrhagic dissecting VA aneurysm and a hypoplastic contralateral VA. Both patients were treated with the VA-PICA bypass and aneurysm trapping, with adequate filling of the PICA territory in the first patient and both the PICA territory and the basilar circulation in the second patient. Vertebral artery-PICA bypass with radial artery interposition graft and subsequent trapping of the dissected VA segment is an alternative to occipital artery-PICA and PICA-PICA bypass for the treatment of hemorrhagic dissecting VA aneurysms that are not suitable for endovascular occlusion.

Cavernous carotid aneurysms: to treat or not to treat?

Most cavernous carotid aneurysms (CCAs) are considered benign lesions, most often asymptomatic, and to have a natural history with a low risk of life-threatening complications. However, several conditions may exist in which treatment of these aneurysms should be considered. Several options are currently available regarding the management of CCAs with resultant good outcomes, namely expectant management, luminal preservation strategies with or without addressing the aneurysm directly, and Hunterian strategies with or without revascularization procedures. In this article, we discuss the sometimes difficult decision regarding whether to treat CCAs. We consider the natural history of several types of CCAs, the clinical presentation, the current modalities of CCA management and their outcomes to aid in the management of this heterogeneous group of cerebral aneurysms.

Revascularization for complex intracranial aneurysms

The modern management of intracranial aneurysms includes both constructive and deconstructive strategies to eliminate the aneurysm from the circulation. Both microsurgical and endovascular techniques are used to achieve this goal. Although most aneurysms can be eliminated from the circulation with simple clip reconstruction and/or coil insertion, some require revascularization techniques to enhance tolerance of temporary arterial occlusion during clipping of the aneurysm neck or to enable proximal occlusion or trapping. In fact, the importance of revascularization techniques has grown because of the need for complex reconstructions when endovascular therapies fail. Moreover, the safety and feasibility of bypass have progressed due to advances in neuroanesthesia, technological innovations, and ~ 5 decades of accumulating wisdom by bypass practitioners. Cerebral revascularization strategies become necessary in select patients who possess challenging vascular aneurysms due to size, shape, location, intramural thrombus, atherosclerotic plaques, aneurysm type (for example, dissecting aneurysms), vessels arising from the dome, or poor collateral vascularization when parent artery or branch occlusion is required. These techniques are used to prevent cerebral ischemia and subsequent clinical sequelae. Bypass techniques should be considered in cases in which balloon test occlusion demonstrates inadequate cerebral blood flow and in which there is a need for Hunterian ligation, trapping, or prolonged temporary occlusion. This review article will focus on decision making in bypass surgery for complex aneurysms. Specifically, the authors will review graft options, the utility of balloon test occlusion in decision making, and bypass strategies for various aneurysm types.