Treatment of Unruptured Large and Giant Carotid Cavernous Aneurysms in Japan at the Time of Flow Diverter Introduction: A Nationwide, Multicenter Survey by the Japanese Society on Surgery for Cerebral Stroke

Background: Flow diverters (FDs) have been introduced for the management of large or giant cavernous carotid aneurysms (CCAs) in addition to conventional modalities, dramatically changing treatment strategies. The aim of this study was to examine the management of unruptured large/giant CCAs in Japan when FDs were being introduced using a nationwide survey.

Methods: 540 unruptured large/giant CCAs treated at neurosurgical teaching departments in Japan between 2012 and 2016 were retrospectively studied.

Results: Large CCAs were treated equally by parent artery occlusion (PAO), FD, and coiling, but giant aneurysms were occluded mainly by PAO. PAO was combined with revascularization in most cases. The nearly complete obliteration rate at final follow-up was higher after PAO (92.4%) than after FD (60.1%) and coiling (70.3%), and PAO was the most effective for ophthalmoparesis. Coiling had higher risks of recurrence and retreatment. Procedure-related major complications were observed in 9.6%. Cranial nerve symptoms were the most common complications, with coiling having significantly higher risks. All treatment modalities achieved good clinical outcomes (92.1-96.1%); however, five delayed rupture cases were observed (PAO 1, FD 4), resulting in two deaths (PAO 1, FD 1).

Conclusions: The nationwide survey reported here determined the status of treatment for unruptured large/giant CCAs in Japan when FDs were being introduced. Since PAO has disadvantages including the long-term hemodynamic effects of ICA occlusion, reconstructive treatment using FDs is optimal for this type of aneurysm; however, PAO can be an option in selected cases given the higher rates of complete occlusion and symptom improvement.