Introduction/Purpose Superior cerebellar artery (SCA) aneurysms (basilar-SCA) are rare yet possess high rupture risk. Endovascular treatment of typically involves coil embolization, with or without adjunctive devices. The interplay between dominance of the vertebral artery (VA), curvature of the basilar artery (BA) and the side of aneurysm projection during microcatheter access has not been previously studied but could have implications for aneurysm access and microcatheter stability during coiling.

Materials and Methods A retrospective review of SCA aneurysms treated at our institution between 2018 and 2022 was performed. Clinical data included demographics, presentation (ruptured vs unruptured), procedural complications and functional outcome (modified Rankin Score, mRS) at follow-up. Angiographic data focused on aneurysm site, size, access, and occlusion class post treatment and at follow up. Special attention was paid to vertebral artery dominance and basilar artery curvature.

Results A total of 9 patients (pts) had 9 SCA aneurysms. 8 were unruptured (88.8%). Over half were associated with multiple aneurysms (5/9, 55.5%), and one-third (3/9) had a previous subarachnoid hemorrhage from another aneurysm. 7/9 were located on left side (77.7%). Codominant and R-dominant VA were present in the majority (7 patients). The basilar artery demonstrated no curve (5 pts) or leftward curve (2) most commonly. 5/7 (71%) left SCA aneurysms were treated from a R VA approach; 3 had codominant and 2 right dominant VA. Mean aneurysm dimensions (in mm) were: height 3.2 (± 1.03), width 2.6 (± 0.74) and neck 2.07 (± 0.85). Coil embolization alone was performed in 2 (22.2%). Adjunctive techniques included balloon remodeling in 2 (22.2%) and stent assistance in 5 (55.5%). Femoral access was used in most cases (7/9). Adequate angiographic occlusion (Raymond-Roy occlusion class RROC 1+2) was achieved in 77.7% (7/9, 4 RROC 1, 3 RROC 2). Complications were noted in 1 patient (11.1%). Follow up rate was 88.8% (8/9), with median duration of 19.15 months (range 7.5-85.2). Adequate aneurysm occlusion was noted in all patients at follow up (100%, 7 RROC 1, 1 RROC 2); improvement from 2/3 to 1 was noted in 4 (44.4%) and worsening from RROC 1 to 2 in 2 patients (50% of RROC 1 at immediate angiography). Good functional outcome was noted in 77%.

Conclusion Our study revealed majority of SCA aneurysms arising on the left side, with codominant or R dominant vertebral arteries and a straight or leftward basilar artery curvature. Most interventions were performed from the right side, with need for adjunctive techniques in majority. Excellent short- and long-term occlusion rates and good functional outcome can be expected in the majority, yet close follow up is required to detect recurrence.

Disclosures M. Sattur: None. M. Mahdi Sowlat: None. S. Samir Elawady: None. A. S. Sumal: None. A. M Spiotta: None.