Ruptured Primitive Trigeminal Artery Aneurysm Leading to Internal Carotid Artery Cavernous Sinus Fistula Intervention.

Background: Internal carotid artery cavernous sinus fistula (CCF) occurs when the cavernous segment of the internal carotid artery or its branches within the cavernous sinus rupture, creating an abnormal communication between arterial and venous blood. This leads to increased pressure within the cavernous sinus and a range of clinical manifestations. The prevalence of CCF is ~0.17% to 0.27%. Its etiology can be classified into 2 main types: traumatic, accounting for about 75% of cases, and spontaneous, accounting for the remaining 25%. The primitive trigeminal artery (PTA) is a rare remnant of the embryonic circulatory system that forms a connection between the internal carotid artery and the vertebrobasilar system. Its prevalence is estimated at 0.1% to 0.6%. A rupture of a PTA aneurysm leading to a cavernous sinus fistula of the internal carotid artery is even more uncommon. Current clinical approaches to managing this condition are still evolving and require further study.

Case Report: A 53-year-old female patient presented with a one-month history of diplopia. Digital subtraction angiography (DSA) revealed a ruptured aneurysm of the primitive trigeminal artery, resulting in a cavernous sinus fistula of the internal carotid artery. After discussions with her family, she underwent successful interventional embolization to treat the fistula. At the 6-month follow-up, the patient's diplopia had resolved completely, and no recurrence of the cavernous sinus fistula was observed on DSA.

Conclusion: Rupture of a primitive trigeminal artery aneurysm resulting in a cavernous sinus fistula of the internal carotid artery is an exceptionally rare condition. Transarterial embolization has proven to be a feasible treatment approach; however, due to the limited number of reported cases, treatment strategies require further investigation and refinement.