Introduction/purpose Endovascular coil embolization with or without stenting for the treatment of posterior communicating artery (PcommA) aneurysms is well established. However, if the PcommA originates from the base of the aneurysm, complete aneurysm obliteration with preservation of the PcommA may not be possible without the use of stent-assisted coiling (SAC). Depending on the angle of the origin of the PcommA, the use of an anterograde approach from the proximal carotid to distal PcommA may not be possible. However, the use of a retrograde approach from the PcommA to the distal carotid may be possible. We present three patients with wide necked PcommA aneurysms in which the neck of the aneurysm was approached retrograde through the posterior circulation to allow for SAC in order to allow for complete aneurysm obliteration with preservation of the PcommA.

Materials/methods We retrospectively reviewed all cases of SAC performed by the senior author from June 2009-January 2014 to identify cases in which a PcommA aneurysm was treated via the retrograde approach. Three patients met the inclusion criteria. Medical records were reviewed for clinical course and imaging characteristics of the aneurysms. We also reviewed the operative reports and angiographic imaging of each endovascular treatment of each patient. All procedures were performed under general anesthesia and patients were started on Clopidogrel and Aspirin prior to stenting. Bifemoral access was obtained to allow 1)a coiling microcatheter access to the aneurysm via an anterograde approach through the carotid circulation, and 2)a stent delivery catheter across the neck of the aneurysm from the posterior communicating artery to the distal internal carotid artery via the posterior circulation. Following stent deployment, coil embolization was performed.

Results Retrograde SAC was performed in three patients with an average age of 58±8 years. Two patients had previously treated aneurysms and one had an untreated aneurysm. The average size of filling aneurysm was 7.03±2.66 mm. The Enterprise® stent (Codman & Shurtleff, Inc., Raynham, MA) was used in all cases. Immediate angiographic results in two cases revealed no residual filling, and the third case had only trace residual filling. However at over 1-year follow-up angiography, this aneurysm was completely occluded. The patency of the PcommA was maintained in all three cases. There were no clinical complications associated with retrograde SAC in this series.

Conclusion The retrograde approach for SAC of PcommA aneurysms is a viable method to allow for complete aneurysm obliteration and preservation of the PcommA when other approaches would risk either incomplete obliteration with preservation of the PcommA or complete obliteration at the risk of occlusion of the PcommA. This approach may allow for complete and safe treatment of PcommA aneurysms that would have otherwise required microsurgical clipping for vessel reconstruction of the PcommA to maintain its patency. To our knowledge, we present the largest series to date of patients undergoing retrograde SAC of PcommA aneurysms.

Learning objective Retrograde stent assisted coiling is a useful technique which allows for complete aneurysm obliteration while maintaining the patency of the posterior communicating artery in select aneurysm of the posterior communicating artery.

Disclosures J. Caplan: 6; C; Stryker. J. Huang: None. R. Tamargo: None. M. Radvany: 1; C; Siemens Medical. 6; C; CeloNova Biosciences, Inc.