Stent-assisted coil embolization for an unruptured vertebral artery–posterior inferior cerebellar artery aneurysm with retrograde access via type 1 persistent primitive proatlantal artery: A case report

Vertebral artery (VA)-posterior inferior cerebellar artery (PICA) aneurysms are rare lesions that are difficult to treat with both endovascular and surgical techniques. Tight angulation of the PICA from VA may make access to the PICA difficult from ipsilateral VA if adjunctive techniques are needed. Recently, the safety and efficacy of retrograde access have been reported. We report a case of endovascular treatment for a VA-PICA aneurysm with a stent-assisted technique using retrograde access via contralateral persistent primitive proatlantal artery (PPA). The patient was a 76-year-old woman with an unruptured VA-PICA aneurysm on the dominant VA side. Coil embolization with a stent-assisted technique using retrograde access seemed appropriate. However, the origin of the left VA was not confirmed. Left common carotid artery angiography demonstrated that the PPA (type 1) branching from external carotid artery joined the VA V4 segment. Retrograde access via the PPA for stenting was performed. A microcatheter for stenting was retrogradely advanced to the right PICA at ease. After deploying the stent, coil insertion was completed from the right VA, and the final angiogram showed adequate occlusion of the aneurysm with preservation of the PICA. Thus, PPA may be an approach route in the treatment of VA-PICA aneurysms with unconfirmed contralateral VA orifice and apparent PPA on angiography, when retrograde access is needed.