Introduction: Superior cerebellar artery (SCA) aneurysms are usually grouped with other more difficult to treat aneurysms that arise from the upper basilar artery or more broadly, the posterior circulation. However, the SCA aneurysm has distinctive anatomy that facilitates safe surgical management, notably few associated perforating arteries and excellent exposure in the carotid-oculomotor triangle. Herein, we present a large surgical series is reviewed to demonstrate the safety and relevance of microsurgical therapy as an alternative to endovascular therapy.

Methods: A consecutive series of 62 patients harboring 63 SCA aneurysms was retrospectively reviewed using a prospectively-maintained database, focusing on clinical characteristics, surgical techniques, and clinical outcomes.

Results: Of 31 patients (49%) presenting with subarachnoid hemorrhage, the SCA aneurysm was the source in 16 (25%). 33 aneurysms were complex (52%) and 43 patients (59%) had multiple aneurysms. 57 SCA aneurysms (90.5%) were clipped and five were bypassed/trapped or wrapped. Complete angiographic occlusion was achieved in 91.7%. Permanent neurological morbidity occurred in three patients and three patients that presented in coma after subarachnoid hemorrhage died. All patients with “simple” aneurysms and without subarachnoid hemorrhage had improved or unchanged mRS scale scores. Overall, outcomes were stable or improved in 82.5% of patients.

Conclusions: SCA aneurysms are more favorable for microsurgical clipping than other upper basilar artery aneurysms because of their unique anatomy. Although endovascular therapy is considered the first-line treatment of posterior circulation aneurysms generally, our results with SCA aneurysms demonstrate that microsurgery should be considered as a primary treatment in many patients.

Patient Care: Superior cerebellar artery (SCA) aneurysms are usually grouped with the other aneurysms that arise from the upper third of the basilar artery, namely basilar bifurcation and posterior cerebral artery aneurysms. In many series and trials, the relative infrequency of these aneurysms, as well as those arising at the origins of the posterior inferior cerebellar artery and anterior inferior cerebellar artery, requires binning them into the category of posterior circulation or vertebrobasilar aneurysms. Gone is the granularity of aneurysm-specific outcome analysis after therapeutic intervention, as is an appreciation of anatomical and microsurgical factors impacting these aneurysm-specific outcomes. SCA aneurysms are different from other upper basilar or posterior circulation aneurysms that are associated with high rates of surgical morbidity and mortality. With this distinction in mind, we present the largest surgical series of superior cerebellar artery aneurysms in order to review the treatment methods and outcomes for these rare lesions, and to demonstrate the relevance of microsurgical therapy as an alternative to endovascular therapy.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) identify the operative corridors to approach superior cerebellar artery aneurysms 2) identify some of the challenges with complex aneurysm configurations 3) identify which patients with posterior circulation aneurysms may benefit from microsurgical treatment over endovascular treatment

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