Microsurgical management of 883 previously coiled intracranial aneurysms: a systematic review, meta-analysis, and meta-regression of its effectiveness and safety.

[OBJECTIVE] With the increasing number of intracranial aneurysms (IAs) treated by endovascular coiling, more residual and recurrent IAs are being encountered. This study aimed to evaluate the effectiveness and safety of the microsurgical management of these previously coiled IAs.

[METHODS] Systematic searches of the Medline, Embase, and Cochrane Central databases were performed. The primary outcome was good functional outcome (modified Rankin Scale score 0-2 or Glasgow Outcome Scale score 4-5) and unchanged/improved functional outcomes at the last follow-up. Secondary outcomes included intraoperative rupture, complete occlusion confirmed on imaging, and perioperative complications and death within 30 days.

[RESULTS] Thirty-nine studies reporting on 874 patients with 883 previously coiled IAs managed by microsurgery were included in the meta-analysis. Of the 883 IAs, 656 (74.3%), 167 (18.9%), 44 (5.0%), and 16 (1.8%) underwent direct clipping, clipping with coil removal, bypass, and trapping, respectively. Forty-five (5.1%), 806 (91.3%), and 32 (3.6%) IAs were classified as Gurian group A, B, and C. IAs were located anteriorly in 88.2% and posteriorly in 11.8%; 45.3% were < 7 mm, 31.3% were 7-12 mm, 14.6% were 13-24 mm, and 8.8% were > 25 mm. The overall mean clinical follow-up duration was 33.7 months. Overall proportions of intraoperative rupture, perioperative stroke, and death were 0.1% (95% CI 0.0%-1.1%, I2 = 25.2%), 8.2% (95% CI 5.85%-11.34%, I2 = 52.8%), and 3.7% (95% CI 2.63%-5.24%, I2 = 0.0%), respectively. The proportions of complete occlusion, good, and improved/unchanged functional outcomes were 97.2% (95% CI 95.82%-98.13%, I2 = 0.0%), 82.9% (95% CI 79.67%-85.69%, I2 = 5.1%), and 92.3% (95% CI 89.27%-94.54%, I2 = 0.0%), respectively. Direct clipping of unruptured anterior circulation IAs was associated with the lowest proportion of intraoperative rupture, perioperative stroke, and death. Direct clipping was also associated with the greatest proportion of complete occlusion, good functional outcome, and improved/unchanged neurological outcome. Microsurgery within 1 month of endovascular coiling and management of Gurian group C IAs were associated with greater proportions of perioperative death.

[CONCLUSIONS] Microsurgical management of previously coiled IAs is an effective and safe strategy in well-selected patients. Important factors to consider in the management of these IAs include the size and location of the IA, rupture status at initial presentation, indication for microsurgery, and type and timing of microsurgery.