Flow Diversion as Salvage for Failure of Previously Treated Intracranial Aneurysms

Introduction: Indications for flow diversion continue to evolve. Risks and efficacy of flow diversion after previous surgical (clipping) or Endovascular (coiling, stent assisted coiling, previous flow diversion) treatment is a topic that warrants further investigation. We aimed to assess safety and efficacy of PED in previously treated intracranial aneurysms.

Methods: In our retrospectively maintained institutional database, we identified patients who underwent PED for non-occluded or recurrent aneurysms following prior treatment with surgical or Endovascular modalities. Radiographic evidence of occlusion status at first follow up and last follow up, clinical outcomes including complications and modified Rankin Scale (mRS) scores were extracted for comparison.

Results: In total, 68 patients were included. Among them, 24 had previous PED, 26 coiling, 3 stent-assisted coiling, 1 stent, 12 clipping, 2 coiling and clipping. Three patients had radiographic watershed infarct without any clinical symptoms, 2 patients had post-operative ischemia with neurologic symptoms, another 2 patients had intracranial hemorrhagic with permanent deficits. In the prior PED group, 29% had complete occlusion at 6 months follow up, and 41.7% had complete obliteration at last follow up. In the previously coiled group, 69.2% and 76.9% had complete occlusion at 6 months and last follow up respectively. In the previously clipped group 91.7% had complete obliteration at 6 months, 100% at last follow up. All lesions had complete or near complete occlusion by 6 months in stent-assisted coil, stent, combined coiling and clipping group

Conclusion : Utilization of PED in previously treated residual or recurrent aneurysms is relatively safe (4/68 with deficit; 5.9%), with many of these lesions complex and high risk for other forms of treatment. Re-treatment with flow diversion is associated with a high rate of complete occlusion in patients with previous endovascular coiling, stent-assisted coiling, stenting or clipping. However, its efficacy is lower in patients with previous PED placement.