Delayed thrombosis of a complex fusiform ICA aneurysm treated with flow reversal and partial occlusion: case report and brief review of possible mechanisms.

Immediate complete occlusion of complex cerebral aneurysms associated with perforating or major branch arteries may cause serious ischemic complications due to poor collateral supply. Flow reversal with concomitant proximal occlusion is an important therapeutic strategy in clinical practice and induces gradual thrombosis in the aneurysm within weeks or months, providing a time window for collateral progression. Herein, we report a case of delayed thrombosis of a complex fusiform aneurysm of the ICA following flow reversal with EC-IC bypass and concomitant partial coiling with parent artery occlusion. The effects of hemodynamic alterations on collateral circulation and intra-aneurysmal thrombosis are briefly discussed in the light of the literature.