Carotid-Cavernous Fistulae

Carotid cavernous fistulae are abnormal connections between the carotid artery and the cavernous sinus. The carotid artery is a major artery of the neck which carries blood to the head and brain. The cavernous sinus is a large vein behind the eye. It receives blood from the orbit or eye socket, the pituitary gland (an organ located at the base of the brain that is involved in hormone regulation), and the brain.

The fistulae, or abnormal connections, can result from several causes. Trauma or injury such as minor falls or severe wounds are the most common causes or carotid-cavernous fistulae in young men. Clotting and subsequent reopening of the sinus can be another cause. In addition, rupture of an aneurysm, which refers to widening and weakening of the artery, can occur at the point where it passes through the sinus.

Without treatment, it is estimated that as many as 90% of patients will lose vision.

Carotid cavernous fistulae can be classified as direct or indirect. Direct refers to the connection of the carotid artery with the cavernous sinus. Indirect refers to the connection of branches of the carotid arteries through the wall of the cavernous sinus. Indirect fistulae are more common in postmenopausal women than in any other population.

Patients with carotid cavernous fistulae may experience symptoms such as proptosis-pulsating, bulging of the eye, redness and swelling of the membrane covering the eyeball, glaucoma or increased pressure in the eye, double vision or loss of vision in the eye, and pain. Without treatment, it is estimated that as many as 90% of patients will lose vision.

Due to their location, fistulae are difficult to treat surgically. However, they can be successfully remedied through a procedure that is similar to an angiogram. A catheter is placed into the leg and guided into the blood vessels. Material is then injected to block off the fistula and/or the vein. This procedure may take place several days prior to surgery and significantly reduces the risk of blood loss during surgery.

The embolization procedure from start to finish
Prior to undergoing embolization, patients are expected to sign a consent form and will have the opportunity to have questions answered. The anesthesiologist will administer medications and fluids through the use of an intravenous line (IV) into a vein in the hand or arm. He or she will also administer general anesthesia so that the patient will be completely asleep for the procedure. Blood pressure will be monitored through an A-Line, a thin flexible tube or catheter placed in an artery in your wrist. An electrocardiogram (EKG) will monitor heart rate and rhythm as well as oxygen levels. A specific type of catheter known as a Foley will be placed in the bladder to allow urine to drain.

Once the procedure is complete, the patient will be transferred from the operating room to either the Surgical Intensive Care Unit (SICU) or the Post-Anesthesia Care Unit (PACU). Here, a heart monitor will closely monitor vital signs. This machine is very sensitive and often sounds inadvertently; this is not cause for alarm. The nursing staff will assist in changing positions, but bed rest is required. Eventually, the patient can look forward to a normal diet and transfer to a room on a surgical floor. The Foley catheter will also be removed prior to leaving the bed for the first time.

Patients are expected to keep the leg that underwent surgery straight for several hours and a tube may remain in place at the puncture sight for several days. Once it is removed, the physician will apply pressure for about 20 minutes to prevent bleeding, and a device may be used to seal the puncture.

Sometimes treatment may entail that the carotid artery itself be blocked off to close the fistula. When this occurs, tests are carried out first to ensure that there is enough flow to the brain from the other arteries.