Cavernous Carotid Fistula
Cavernous carotid fistulas (CCFs) are abnormal connections between the blood vessels that take blood to and from the brain: the internal carotid artery (ICA), the external carotid artery, and the cavernous sinus or its dura (the thin membrane that covers the cavernous sinus). The integrity of the cavernous sinus and its dura are particularly important because blood is toxic to a number of nearby sensitive neural tissues.
CCFs are classified as either indirect (type A, or dural) or direct (type B, C, and D). Indirect CCFs are usually spontaneous and have no known cause. Direct CCFs may result from trauma, rupture of a cavernous carotid aneurysm, or a tear in the wall of a weak cavernous ICA caused by congenital collagen vascular disease.
CCF symptoms vary, and can include:
- bulging eyes
- swelling of the membranes that cover the outside of the eyes and line the eyelids
- forward displacement of the eyeballs
- deteriotating vision
- cranial nerve palsies
- nosebleed
- headache
- bruit (a blowing sound in the vessel that can be heard with a stethoscope)
- tinnitus (ringing in the ears)
In rare cases, a type of stroke called subarachnoid hemorrhage may occur.
CT and MRI can be used to evaluate some aspects of a CCF. Angiography is used to map the exact arterial and venous anatomy. In cases where fistula flow is so rapid that the fistula site cannot be identified, arteriography can be done with simultaneous carotid compression.
Treatment
Many CCFs will close spontaneously. This is more common for indirect type fistulas. Those lesions that present with worsening proptosis, pial venous drainage, deteriorating vision, epitaxis, increased intracranial pressure, glaucoma, and ophthalmoplegia require urgent or semi-urgent attention.
One treatment option is carotid compression therapy — compressing the carotid artery to reduce blood pressure from the CCF. Under reduced pressure, the CCF may close itself. Compression therapy is most effective with indirect CCFs.
In direct fistulas, doctors may use transarterial embolization — inserting coils or detachable silicon balloons through the arteries involved to block the hole in the artery.
Transvenous treatments — approaching the CCF with a catheter from the venous side — can be used for either direct or indirect CCFs. Another option for both types of CCF is to selectively catheterize the superior ophthalmic vein, a procedure that may be performed through a catheter placed in the groin or by surgically exposing the vein.
To learn more about cavernous carotid fistula treatments at MINC, or to request a consultation, go to appointments & referrals.