Failure of Flow Diverter Treatment of Intracranial Aneurysms Related to the Fetal-type Posterior Communicating Artery

Abstract

PurposeThe pipeline embolization device (PED) is a flow diverter that has shown promise in the treatment of intracranial aneurysms. Close to one-fifth of aneurysms, however, fail to occlude after PED placement. This study aims to identify anatomical features and clinicopathologic factors that may predispose failed aneurysm occlusion with the PED.Materials and MethodsWe retrospectively reviewed all anterior circulation unruptured saccular aneurysms treated with the PED in a single-center. The primary outcome measure was angiographic occlusion. Anatomical features and potential predictors, including gender, aneurysm location, size, height, aspect ratio, neck width, prior treatment and the number of PED, were studied using binary logistic regression.Results29 anterior circulation unruptured saccular aneurysms with a mean size of 6.99 mm treated with the PED in a single center were retrospectively studied. The overall occlusion rate was 79.3% after a mean follow-up of 9.2 months. Four aneurysms were related to the fetal-type posterior communicating artery (PComA), and all were refractory to flow diverter treatment. Female gender was significantly associated with a higher occlusion rate. We present the anatomical features and propose possible pathophysiological mechanisms of these PComA aneurysms that failed flow diverter treatment.ConclusionA PComA aneurysm with persistent fetal-type circulation appears to be particularly refractory to flow diverter treatment, especially when the aneurysm incorporates a significant portion of the PComA. Our experience suggested that flow diverting stents alone may not be the ideal treatment for this subgroup of aneurysms, and alternative modalities should be considered. Female patients were found to have a significantly higher rate of treatment success.

Factors Affecting the Obliteration Rate of Intracranial Aneurysms Treated with a Single Pipeline Embolization Device

“…They found that the female gender had a higher rate of aneurysm occlusion, but failed to show any statistically significant association between other factors and the result of the PED treatment. 13 Aneurysms originating from the PCOM itself rather than the ICA at the origin of PCOM, may not have sufficient pipeline coverage of the aneurysm neck, which could explain the failed obliteration in these studies. Anatomical characteristics of aneurysms and branching artery are as important as flow or demand theory in terms of obliteration success rate with PED.…”

“…21 Tsang et al reported similar obliteration rates for PCOM aneurysms with fetal PCA. 13 They evaluated the effect of factors such as gender, aneurysm location, size, aspect ratio, neck-width and prior treatment on obliteration rate. They found that the female gender had a higher rate of aneurysm occlusion, but failed to show any statistically significant association between other factors and the result of the PED treatment.…”

“…8-11 In addition, the use of the PED in treatment of recurrent previously-coiled aneurysms has been described to be safe and effective in achieving aneurysm occlusion. 12 In a recent review article, the occlusion rate of aneurysms treated with the PED was reported as 83% at six months 13 with the overall morbidity and mortality rate of 1.23% and 1.18% respectively. 14 There are few studies evaluating the factors influencing aneurysm obliteration rate, and most of the previous reports did not isolate aneurysms treated with a single device compared to multiple devices.…”

“…14 There are few studies evaluating the factors influencing aneurysm obliteration rate, and most of the previous reports did not isolate aneurysms treated with a single device compared to multiple devices. 13,15 …”

Comment on “Failure of the Pipeline Embolization Device in Posterior Communicating Artery Aneurysms Associated with a Fetal Posterior Cerebral Artery”

“…However, their review of the previously published literature is incomplete and indeed this phenomenon has been described by our own series of 4 patients several months earlier [2]. Soon, thereafter, it was described by Tsang et al [3], and followed by the recent article by Zanaty et al These publications were likely in development simultaneously, but we wish to point out the previously published literature on the topic and reinforce the phenomenon observed across the 3 series.…”