Flow alteration therapy for impending rupture of intracranial giant aneurysm after flow diverter placement.

Background: Flow diverter (FD) placement is generally effective for intractable internal carotid artery (ICA) aneurysms. However, salvage treatment for the aneurysm enlarging even after FD placement remains to be elucidated. Additional overlapping FD placement is considered the first-line treatment for residual or recurrent aneurysms. However, it is unclear whether overlapping FD is also effective for enlarging giant aneurysms that are considered impending rupture status. Although parent artery occlusion is a promising option, treatment strategy must be optimized, especially when a critical perforating artery is involved. Case Description: A 74-year-old woman experienced rapid symptomatic growth of her giant supraclinoid ICA aneurysm 10 months after FD placement. We assumed that reinforcement of flow diverting effect alone would be less effective for this extremely intractable aneurysm with more aggressive clinical feature so that surgical bailout by parent artery occlusion was planned. Complete ICA obliteration underneath the aneurysm was unavailable due to the presence of anterior choroidal artery. Thus, we took a flow alteration strategy, where we created minimal retrograde flow through the parent artery by a combination of an extracranial-intracranial bypass and targeted endovascular proximal parent artery obliteration, resulting in prevention of aneurysmal rupture and further growth. Conclusion: Impending rupture of the intracranial giant aneurysm after FD placement may be controllable with a tailor-made parent artery occlusion strategy even when a critical perforating artery is involved.