Increase in Hypoplastic A1 or P1 Caliber After Anterior or Posterior Communicating Artery Flow Diverter Stent Challenge

Introduction: Anterior ( Acom ) or posterior communicating ( Pcom ) endovascular aneurysm treatment with flow diverter stents ( FDS) has been a controversy especially with hypoplastic A1 or P1 segments.

Methods: Retrospective study of Acom and Pcom aneurysms treated with flow diversion stents associated with a contralateral hypoplastic A1 or ipsilateral P1, respectively, in three major cerebrovascular centers.

Results: We found 5 patients with a poor A1 or P1 collateral to the Acom or Pcom territory covered by a flow diverter stent. Three patients had a hypoplastic A1 contralateral to the A1-A2 stent placement covering the acom origin. Two patients had a hypoplastic P1 ipsilateral to the Pcom covered to treat ICA aneurysms. All of these patients had a compensatory increase of the respective A1 or P1 in response to the FDS. No patient had new neurological symptoms or deficits after the procedure or during the follow up ( > 6 months ).

Conclusion : FDS placement into A1-A2 segments for Acom aneurysms treatment with a contralateral hypoplastic A1 and for ICA - Pcom aneurysms with an ipsilateral hypoplastic P1 could lead to remodeling and increase is caliber of hypoplastic segments with no neurological deficits in this small series of cases.