High-flow bypass surgery for a large cavernous internal carotid artery aneurysm associated with persistent primitive trigeminal artery: A case report

Background: Giant cavernous internal carotid artery (ICA) aneurysms present with therapeutic challenges, especially if associated with a persistent primitive trigeminal artery (PPTA). Although flow diverters (FDs) are commonly used, the PPTA can maintain collateral inflow to the aneurysm sac, preventing complete thrombosis. Case Description: A 74-year-old woman presented with progressive oculomotor nerve palsy and visual decline. High-flow external carotid-middle cerebral artery bypass with distal ICA occlusion beyond the aneurysm was performed. The bypass remained patent without infarction, and partial aneurysm thrombosis occurred, whereas PPTA flow was preserved. Conclusion: This case emphasizes the importance of individual microsurgical strategies if FD treatment may be ineffective due to complex embryonic vascular anatomy.