Editorial: Basilar occlusion

Abstract

In this issue of the Journal of Neurosurgery, Kellner and colleagues4 present an excellent retrospective analysis of their experience with surgical proximal basilar artery (BA) occlusion for complex BA aneurysms. Over a 22-year period a total of 15 patients were treated in this manner. Patients underwent this procedure if direct surgical clipping or endovascular coiling were believed to be unsafe and there was good collateral flow to the posterior circulation through at least 1 robust posterior communicating artery (PCoA). Considering the difficult lesions treated, the results were excellent: 80% of the patients were neurologically intact 1 month after surgery, there was no postoperative aneurysmal bleeding during an average follow-up of 3 years (range 2 months to 18 years), and 57% of the surviving patients were found to have their aneurysm completely occluded on late angiographic follow-up. As the authors will agree, the limitations of the study include its retrospective nature, its inherent selection bias, the small cohort of patients, and the heterogeneity of the lesions treated. However, we believe this is an important article because it reminds us that the time-honored technique of proximal artery (Hunterian) ligation remains a viable and effective treatment option. Despite advances in modern microsurgical and endovascular techniques, aneurysm obliteration with preservation of the parent artery may not always be possible, may carry significant morbidity, or may be unlikely to provide durable results. In such cases proximal artery occlusion is a reasonable alternative, provided there is adequate collateral circulation. We would like to make some comments emphasizing certain aspects of the article. Although the authors do not elaborate on their intraoperative decision making, they state that BA occlusion was used as a fallback treatment after direct clipping was aborted because of anatomical concerns. We completely agree with this approach and cannot overemphasize that clinical decision making does not stop once a decision has been made to operate; rather, it is a continuous process assessing the risks and benefits throughout the procedure up to the point of definitive treatment. On many occasions during his career, the senior author of this editorial (R.C.H.) has deviated from his original surgical plan or aborted a procedure after finding an unexpected morphological feature, such as calcification at the neck of an unruptured aneurysm, that in his opinion increased the surgical morbidity as compared with his preoperative estimation.3 We also agree with the authors that in many instances surgical clip occlusion in the BA is safer than endovascular coil occlusion. A long vessel segment is frequently required to place a solid occlusive coil mass during endovascular proximal artery sacrifice. Such long segments devoid of critical branches and/or perforators are found in the internal carotid arteries (ICAs) and vertebral arteries (VAs); however, endovascular coil occlusion of the BA is problematic due to the lack of such a perforatorand branch-free zone. Furthermore, the risk of coil migration remains a concern. In contrast to coil occlusion, surgical clip occlusion in the BA has the advantage of directly visualizing the perforating vessels, which are frequently not visualized on angiography, and placing the clip in a segment of the artery devoid of any branches. The authors use the term “point occlusion,” which in our opinion nicely describes the selective nature of clip occlusion. We would like to comment on the authors’ decision to delay proximal vessel occlusion in patients presenting with subarachnoid hemorrhage. Although the authors do not specifically mention the reason, we presume this delay in treatment was to minimize the potential ischemic complications in patients who would develop vasospasm. Patients who demonstrate robust collaterals or have tolerated balloon test occlusion (BTO) early after rupture of the aneurysm may not tolerate occlusion if vasospasm develops several days later. This is why we prefer, in the setting of subarachnoid hemorrhage, to treat patients conservatively and wait until the period at risk for vasospasm has subsided before proximal artery occlusion is undertaken. The authors frequently performed a preoperative Editorial See the corresponding article in this issue, pp 319–327.