Flow diversion for indirect carotid-cavernous fistula: Still an off-label indication?

Background: Flow diversion (FD) is an established treatment for large or giant wide-necked unruptured intracranial aneurysms. In the past few years, the use of flow diverter devices was extended to several other "off-label" indications, including solitary or adjunctive treatment to coil embolization for direct (Barrow A type) carotid cavernous fistulas (CCFs). The use of liquid embolic agents still represents the first-line treatment for indirect CCFs. Typically, the ipsilateral inferior petrosal sinus or superior ophthalmic vein (SOV) is the preferred transvenous routes to access CCFs. In some cases, vessel tortuosity or different features make the endovascular access challenging, thus requiring different approaches and strategies. The aim of the study is to discuss rational and technical aspect in treating indirect CCFs referring to the most up-to-date literature. An alternative experience-based endovascular strategy with FD is described. Methods: We report the case of a 54-year-old woman diagnosed with indirect CCF and treated with flow diverter stent. Results: After multiple unsuccessful attempts at transarterial right SOV catheterization, a right indirect CCF fed by a single trunk at the ophthalmic origin from the internal carotid artery (ICA) was treated by ICA stand-alone FD. Blood flow was redirect and successfully reduced through the fistula, with immediately postprocedure improvement of the patient's clinical status (ipsilateral proptosis and chemosis). Ten-months radiological follow-up showed the complete obliteration of the fistula. No adjunctive endovascular treatment was performed. Conclusion: FD appears a reasonable alternative stand-alone endovascular strategy also for selected difficult-to-access indirect CCFs, when all conventional routes are judged unfeasible. Further investigations will be necessary to better define and support this potential lesson-learned application.