An Alternative Rescue Procedure for Neuroform Atlas® Withdrawal During Deployment: A Report of Two Cases.

Neuroform Atlas (NFA; Stryker Neurovascular, Fremont, CA, USA) is a useful and safe device for the treatment of broad-necked and unruptured cerebral aneurysms. Rarely does a proximal shift of both the stent and delivery catheter occur during deployment, and it can be complex to treat. We present two cases in which an NFA that had migrated proximally during deployment was successfully retrieved. In Case 1, a left internal carotid artery (ICA) and posterior communicating artery (Pcom A) bifurcation aneurysm of 12.8 mm in maximum diameter was treated by the stent-assisted technique. An NFA stent (4 ´ 21 mm) was selected for use after placement of three coils. During deployment of the stent from the left Pcom to the ICA, withdrawal of the system in the proximal direction resulted in part of the stent falling into the aneurysm. The half-released stent was retrieved carefully because we considered that complete deployment of the stent would result in inadequate treatment and fatal consequences in the long term. After Case 1, an experiment was conducted to determine whether it was safe to retrieve the NFA into the parent catheter. In Case 2, we experienced the same situation during the procedure of an anterior communicating artery aneurysm. Based on the experience of Case 1, we were able to perform stent retrieval in Case 2 without hesitation. The sudden withdrawal of an NFA stent can occur during the placement procedure. If surgeons encounter proximal migration during NFA deployment, retrieval of the NFA may be an option.