ABSTRACT NUMBER: ESOC2026A1276 WHEN HEADACHE AND DIPLOPIA HIDE A LOW-FLOW THREAT: INDIRECT CAROTID–CAVERNOUS FISTULA

Abstract Background and aims Carotid–cavernous fistulas (CCFs) are rare arteriovenous shunts between carotid system and cavernous sinus. Indirect, low-flow CCFs may present with subacute and nonspecific symptoms, leading to diagnostic delays. Headache and isolated cranial nerve palsies may precede ocular signs. Management strategies range from conservative treatment to endovascular intervention. We report two cases of indirect CCFs with different clinical severity and therapeutic approaches, highlighting diagnostic challenges and individualized management. Methods Patient A, a 63-year-old man, presented with subacute headache and acute right sixth cranial nerve palsy. CT head scan and Transcranial Doppler were unremarkable. Brain MRA, CTA and digital subtraction angiography (DSA) confirmed a right-sided indirect low-flow CCF. Patient B, a 64-year-old man developed changes in his usual migraine, followed by diplopia, ptosis, conjunctival hyperemia and orbital pain. Brain MRA and CTA were unremarkable. DSA revealed an indirect CCF. Both patients had Barrow type D fistulas. Results Given clinical stability and absence of visual compromise, patient A was initially managed conservatively with analgesia and carotid compression maneuvers. Persistent symptoms led to subsequent endovascular embolization with coils, without complications. In contrast, patient B presented with severe and progressive symptoms and underwent primary endovascular treatment. Both patients improved gradually and are asymptomatic nowadays. Conclusions - Painful diplopia should alert us for cavernous synus pathology, specially in the presence of hyperemia and ptosis. - Brain MRA/CTA assist with diferential diagnosis. DSA is essential for diagnostic and therapeutic aproaches of CCFs. - Clinical suspicion remains vital since recovery of vision defficits depends on severity and duration prior to closure. Conflict of interest Sonia Herranz: nothing to disclose