Salvage coiling after the inadvertent proximal migration of a neuroform atlas stent into middle cerebral artery aneurysms: A report of two cases.

Introduction and importance: During endovascular treatment (EVT) of middle cerebral artery (MCA) aneurysms using a Neuroform Atlas stent (NAS), inadvertent proximal migration of the NAS into the aneurysm may occur.

Case presentations: Patient 1 was a 49-year-old female with an unruptured MCA bifurcation aneurysm. During deployment of a 4 × 24-mm NAS from the upper trunk to the main trunk of the MCA, the proximal NAS inadvertently migrated into the aneurysm. Afterward, salvage coiling was continued. The aneurysm was coiled satisfactorily. After EVT, the patient recovered well. Patient 2 was a 58-year-old male who experienced a subarachnoid hemorrhage. Aneurysmal dilatation of the right MCA bifurcation with a ruptured bleb was found. Coiling with the assistance of an NAS was performed. During deployment of a 4 × 24-mm NAS, the proximal NAS inadvertently migrated into the aneurysm. Afterward, salvage coiling was continued. The aneurysm was coiled satisfactorily. After EVT, the patient recovered well. Follow-up magnetic resonance angiography showed no recurrence.

Clinical discussion: During EVT, proximal NAS migration into an MCA aneurysm may occur secondary to stent undersizing or inadvertent proximal advancement, necessitating bailout strategies. ‌Although salvage coiling is technically feasible in these cases, its off-label use remains contraindicated.

Conclusion: When proximal NAS migration into an MCA aneurysm occurs, salvage coiling remains feasible, as the displaced stent can serve as an intraneurysmal scaffold, allowing completion of EVT through subsequent coiling.