An Intraoperative Look at Failure of Flow Diversion: When Additional or Alternative Treatments Should Be Considered

The pipeline embolization device (PED) is a flow-diverting stent that provides an additional treatment modality in the management of intracranial aneurysms. An aneurysm treated with a flow diverter is expected to involute over time, contrary to the immediate obliteration expected by surgical clipping or coiling. Yet, which aneurysms will respond to PED therapy and the time frame to expect full obliteration remain unclear.

We report the unusual case of a 50-year-old woman with multiple (4 total) intracranial aneurysms who underwent multimodality treatment. Two aneurysms were treated with PEDs. Nine months later, the patient underwent a craniotomy for treatment of an additional aneurysm; at the time of surgery, one of the PED-treated aneurysms was noted to be clearly obliterated, and the other was visualized to be filling. The ophthalmic artery arose from the persistently filling aneurysm. The aneurysm was treated by clip ligation without incident.

The rate of PED aneurysm obliteration increases with longer follow-up; however, the time frame for observing a persistently filling aneurysm before additional treatment is considered remains unknown. Some aneurysms may never close even after discontinuation of dual antiplatelet therapy. Ophthalmic artery aneurysms have been noted to fail treatment with PED based on the anatomic relationship of the aneurysm to the ophthalmic artery. This case provokes us to consider factors that may affect the latency to aneurysm obliteration, including aneurysm size, aneurysm morphology, patient gender, failure of previous aneurysm treatment, and duration of time from initial endovascular treatment.