A carotid-cavernous fistula (CCF) is an abnormal communication between the venous cavernous sinus and the carotid artery . The fistula may occur spontaneously, but most commonly occurs following head trauma. In one retrospective study, the time to presentation following injury ranged from one day to as late as two years after injury.
There are two distinct types of carotid-cavernous fistulas:
- A direct fistula is a high-flow fistula between the cavernous internal carotid artery and the cavernous sinus. It is the most common CCF following head trauma and is thought to form from a traumatic tear in the wall of the cavernous internal carotid artery or following the rupture of an aneurysm . Thus, high-pressure arterial blood gains rapid access to the venous system and leads to venous hypertension, causing the presence of an orbital bruit, exophthalmos, proptosis, dilated conjunctival vessels, and cranial nerve dysfunction as seen in this patient.
- Indirect fistulas are low-flow and typically occur between branches of the external or internal carotid artery and the cavernous sinus. The etiology of this type of fistula is unclear, but it has been associated with pregnancy, sinusitis, age, and trauma. These low-flow fistulas generally resolve without treatment .
CCFs typically require endovascular therapy. This may be transarterial (most commonly in the case of direct CCF) or transvenous (most commonly in indirect CCF).
- There are two distinct types of carotid-cavernous fistulas: indirect and direct.
- Clinical findings include venous congestion of the eyelids, palsies of cranial nerves 3, 4, or 6, progressive visual loss, proptosis, and an ocular bruit.
- Once a CCF is diagnosed, it is important to consult the appropriate treating specialist, either an interventional neurologist or neurosurgeon.