Intraoperative rupture of cerebral aneurysms during microsurgical clipping as a risk factor of residual aneurysm enlargement

BACKGROUND: Aneurysm neck clipping is preferable for saccular aneurysms due to stable occlusion. However, postoperative follow-up angiography reveals residual aneurysm in some cases after clipping. Long-term outcomes depend on clipping quality. Currently, there is no consensus regarding further management of these patients. OBJECTIVE: To analyze residual cerebral aneurysms within the first year after surgery, and to identify prognostic factors of enlargement and rupture of aneurysm remnant. MATERIAL AND METHODS: In 2024, clipping of 654 cerebral aneurysms in 550 patients was performed. Residual aneurysms were identified in 49 (7.5%) cases. Clipping quality was estimated in accordance with classification by Yu.V. Pilipenko. Three patients with partial exclusion (R4) underwent redo surgery in early postoperative period. Among 46 patients with residual aneurysms, we enrolled 25 patients with available clinical and angiographic data within one year after surgery. RESULTS: There were no CT signs of residual aneurysm enlargement in 22 (88%) out of 25 cases. In two patients (8%), enlargement of remnant required redo clipping. Fatal rupture of aneurysm remnant occurred in 1 (4%) case. All three patients experienced intraoperative aneurysm rupture during primary surgery. CONCLUSION: Intraoperative rupture significantly increases the risk of residual aneurysm enlargement. Localization in Anterior communicating artery (ACjoA) and clipping quality ≥R3 are potential risk factors requiring further studies of larger cohorts.