Carotid cavernous fistula (CCF) is a rare but potentially serious condition involving an abnormal connection between the carotid artery and the cavernous sinus — a vein-filled space near the base of the brain. Symptoms may include bulging eyes, deteriorating vision, and ringing in the ears.
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What Is Carotid Cavernous Fistula?
Carotid cavernous fistulas (CCFs) are abnormal connections between the blood vessels that take blood to and from the brain, including the:
- Cavernous sinus — Space filled with veins located near the base of the brain.
- External carotid artery — Artery that sends branches to this area of the brain and connects with the internal carotid’s branches to help share blood flow.
- Internal carotid artery — Major blood vessel that passes through the cavernous sinus and sends off smaller branches that supply blood to nearby nerves, the dura (the protective membrane lining the cavernous sinus), and the pituitary gland (which controls hormones).
The integrity of the cavernous sinus and its dura are particularly important because blood is toxic to the sensitive neural tissues nearby.
What are the types of carotid cavernous fistulas?
CCFs are classified as either direct or indirect.
- Direct CCF — Arises directly from the carotid artery.
- Indirect CCF — Originates from smaller branch vessels of the carotid artery. Indirect CCFs are usually spontaneous and have no known cause.
Then CCFs are divided anatomically into types:
Direct CCFs
- Type A CCF – Fistula results from a direct connection between the internal carotid artery (ICA) and the cavernous sinus. The most common form of CCF, these CCFs come on suddenly and typically are caused by trauma, although they may also occur spontaneously. Symptoms rarely resolve without intervention.
Indirect or dural CCFs
- Type B CCF – Fistula results from dural branches of the ICA.
- Type C CCF – Fistula results from dural branches from the external carotid artery (ECA).
- Type D CCF – Fistula results from dural branches from ICA and ECA.
Intervention to treat the CCF is based on:
- Flow velocity of the CCF.
- Progression of symptoms.
- Your specific venous anatomy.
How common is carotid cavernous fistula?
Carotid cavernous fistula is a rare blood vessel disorder. The incidence rate is approximately 0.37 cases per 100,000 people in the U.S. each year.
What causes carotid cavernous fistula?
The cause of indirect CCFs is unknown.
However, direct CCFs may result from:
- Rupture of a cavernous carotid aneurysm.
- Tear the wall of a weak cavernous ICA.
- Trauma — Car accident, fall, sports injury, etc.
Direct carotid cavernous fistula risk factors
Risk factors for direct carotid cavernous fistulas include:
- Being a young man — Statistically most at risk for trauma.
- Having an aneurysm.
- Having a connective tissue disorder (such as collagen disease, fibromuscular dysplasia, or Ehlers–Danlos syndrome).
- Sustaining a head trauma.
Indirect carotid cavernous fistula risk factors
Risk factors for indirect carotid cavernous fistulas include:
- Being an older woman.
- Having a connective tissue disorder (such as collagen disease, fibromuscular dysplasia, or Ehlers–Danlos syndrome).
- Having atherosclerosis — Hardening of the arteries.
- Having diabetes.
- Having hypertension — High blood pressure.
Complications of carotid cavernous fistula
Left untreated, a carotid cavernous fistula can cause damage to cranial nerves and lead to permanent vision loss.
What Are the Signs and Symptoms of Carotid Cavernous Fistula?
Symptoms of CCF include:
- Bruit — A blowing sound in the vessel that can be heard with a stethoscope.
- Bulging eyes.
- Cranial nerve palsies.
- Deteriorating vision.
- Forward displacement of the eyeballs.
- Headaches.
- Nosebleeds.
- Swelling of the membranes that cover the outside of the eyes and line the eyelids.
- Tinnitus — Ringing in the ears.
When should I see a doctor about my carotid cavernous fistula symptoms?
Make an appointment with your primary care provider if you have mild eye symptoms, congestion, headaches, or tinnitus. These signs may point to an indirect CCF, which can sometimes resolve spontaneously but should be evaluated by your doctor.
Seek immediate medical attention if you have:
- Diplopia (double vision) or blurred vision
- Droopy eyelid or limited eye movement.
- Elevated eye pressure or vision impairment.
- Eye issues — Puffiness, redness, swelling.
- Eye pain or headache.
- Head injury.
- Proptosis — Bulging eye or difficulty closing the eye.
- Pulsing sensation in the eye or hearing bruit (a swishing sound).
- Sudden onset of eye symptoms after head trauma (such as a car accident, fall, sports injury).
These symptoms may indicate direct CCF, which can worsen rapidly and usually requires emergency intervention.
How Do You Diagnose Carotid Cavernous Fistula?
Your physician will examine you, take a medical history, and ask you about your symptoms.
Tests to diagnose Carotid cavernous fistula
Carotid cavernous fistulas can be diagnosed by imaging studies such as:
- Angiogram — X-ray test that uses dye and a camera to take pictures of the blood flow in an artery or a vein.
- CT scans — Use x-rays to make detailed pictures of structures inside of the body.
- MRI scans — Use a magnetic field and pulses of radio wave energy to make pictures of organs and structures inside the body.
How Do You Treat Carotid Cavernous Fistula?
Carotid cavernous fistula treatments vary depending on the type of CCF.
Treatment options may include:
Embolization
Embolization is a minimally invasive procedure that involves threading a small catheter or tube through a blood vessel in the groin. It is then navigated to the blood vessels in the brain to create an embolus, or blockage, of blood flow.
During embolization, small coils or detachable silicon balloons are guided through the arteries to stop the abnormal blood flow to the CCF.
Gamma Knife® radiosurgery
Gamma Knife radiosurgery is a painless treatment that uses hundreds of highly focused radiation beams to target tumors and lesions within the brain, with no surgical incision.
As the nation's leading provider of Gamma Knife procedures, UPMC has treated more than 12,000 patients with tumors, vascular malformations, pain, and other functional problems.
