Are microsurgical techniques still indicated for posterior circulation aneurysms? A 10-year longitudinal analysis of clinical and radiological outcomes in the post-endovascular era.

[OBJECTIVE] High rates of retreatment remain a concern after endovascular therapy (EVT) for posterior circulation aneurysms. The authors aimed to analyze the indications and outcomes of microsurgery for posterior circulation aneurysms in the endovascular era.

[METHODS] A single institutional prospectively maintained database was queried from 2015 to 2025.

[RESULTS] Sixty-seven aneurysms were treated with microsurgery. Females comprised 55.2% (n = 37) of the cohort, and the median age was 55.4 years. Aneurysms were located along the posterior inferior cerebellar artery (PICA) in 23 patients, distal intracranial vertebral artery (VA) in 13, basilar apex in 12, posterior cerebral artery (PCA) in 11, and superior cerebellar artery (SCA) in 8. Twenty-five patients (37.3%) presented with acute rupture/subarachnoid hemorrhage (SAH). The median Hunt and Hess grade for patients who experienced SAH was II. The sizes of the aneurysms were < 4 mm in 8 patients, 4-10 mm in 34, 10-24 mm in 20, and > 24 mm in 5. Indications for microsurgery were complex anatomy in 22 patients, large thrombosed aneurysm not amenable to EVT in 13, residual aneurysm after prior EVT in 10, giant aneurysm in 9, distally located aneurysm in 10, partially thrombosed aneurysm in 3, residual aneurysm after prior clipping at an outside hospital in 6, mass effect in 2, and associated hematoma in 1. Microsurgical clip reconstruction was performed in 51 patients (76.1%), trapping with bypass in 5 (7.5%), parent vessel sacrifice in 3 (4.5%), trapping alone in 7 (10.4%), and wrapping in 1 (1.5%). Postoperative digital subtraction angiography (n = 61) confirmed complete occlusion in 54 patients (88.1%). Only 3.0% of patients (n = 2) needed retreatment for an enlarging residual among partially occluded aneurysms (n = 8, 11.9%). Complete occlusion was observed in 100% of SCA aneurysms (n = 8), 84.6% of VA aneurysms (n = 11/13), 90.9% of PCA aneurysms (n = 10/11), 85.7% of PICA aneurysms (18/23), and 75% of BA aneurysms (n = 7). The median follow-up was 27.8 months, and 60 patients (90%) were alive, of whom 55 (93.2%) had a modified Rankin Scale (mRS) score of 0 or 1. SAH-related mortality was seen in 5 patients (20%). Advanced age (p = 0.018) and prior treatment (p = 0.004) predicted poor clinical outcome (mRS score > 3 or mortality) in multivariate logistic regression analysis.

[CONCLUSIONS] Microsurgical techniques yielded excellent complete occlusion rates with low morbidity. Only 3% of patients with posterior circulation aneurysms needed additional treatment for aneurysms that were not amenable to or cured with EVT.