Microsurgery of cerebral aneurysms after endovascular treatment: a systematic literature review (Part 1
Authors:   Moscow Regional Research and Clinical Institute (MONIKI), Dzhindzhikhadze R. S. ,   Moscow, Russian Federation, Gadzhiagaev V. S. ,   Moscow Regional Research and Clinical Institute (MONIKI); Moscow, Russian Federation, Polyakov A. V. ,   Moscow Regional Research and Clinical Institute (MONIKI); Moscow, Russian Federation, Zaytsev A. D. ,   Moscow Regional Research and Clinical Institute (MONIKI); Moscow, Russian Federation, Sultanov R. A. ,   Moscow Regional Research and Clinical Institute (MONIKI); Moscow, Russian Federation, Salyamova E. I. ,   Moscow Regional Research and Clinical Institute (MONIKI); Moscow, Russian Federation
Published: December 2024

Currently, the indications for the use of endovascular techniques for intracranial aneurysm exclusion
have significantly expanded. However, despite the introduction of new methods and devices, endovascular
treatment of cerebral aneurysms has a significant drawback: lower radical exclusion. The long-term risk of
aneurysm recurrence after endovascular embolization is significantly higher and can reach 15-34%, while
the recurrence rate after clipping is about 1-3%. Objective. To conduct a systematic review of the literature on microsurgical treatment of recurrent and residual aneurysms after unsuccessful endovascular treatment, determine the surgical technique features depending on the cause of aneurysm recurrence, localization, size, and shape of the aneurysm, and analyze treatment outcomes, including radical exclusion, complication rates, and clinical outcomes. Materials and methods. A systematic review was conducted according to PRISMA
guidelines. Literature searches were performed in PubMed and Web of Science databases. Patient data were
extracted from the articles, along with morphological parameters of aneurysms: localization, aneurysm size,
neck size, and shape of the aneurysm. Aneurysm occlusion rate was assessed using the modified Raymond-Roy scale. Clinical outcomes were evaluated using the modified Rankin scale. Results. After reviewing the full text of the articles, 42 studies were selected for final analysis. Most commonly, ICA aneurysms were encountered in the described series (40.6%), with the supraclinoid segment of the ICA being the most common location (31.8%).
The average size was 9.81 mm (SD 7.57 mm, 95% CI 8.87-10.70 mm). Radical exclusion of aneurysms during
microsurgical operations in patients after unsuccessful endovascular embolization was observed on average in
94.4% ± 8.4% (95% CI 90.0%-98.0%). Among all postoperative complications, ischemic complications were
the most common, occurring on average in 6.4% of patients in the series (SD ±6.0%, 95% CI 3.9%-8.8%).
The only proven factor increasing the risk of complications was the use of stent assistance during aneurysm embolization. There was also a tendency towards statistical significance for aneurysm localization, with the risk being slightly higher for vertebrobasilar aneurysms. Conclusion. Despite technical difficulties, microsurgical treatment of residual and recurrent aneurysms is a safe and effective method in most cases, with only a small number of patients requiring unconventional techniques such as coil removal, thrombectomy, or deconstructive procedures combined with revascularization. Aggressive treatment is recommended in all cases where longterm angiographic follow-up shows an increasing residual or recurrent aneurysm.