Carotid cavernous fistula

Carotid cavernous fistula is a pathological fistula that occurs as a result of damage to the internal carotid artery in the place where it passes through the cavernous sinus. 

The most common cause of the formation of carotid-cavernous anastomosis is the craniocerebral trauma, less often - infectious processes, anomalies in the development of the internal carotid artery.

Arteriovenous fistula is a pathological communication between the artery and the vein. Blood in the affected vein becomes "arterial", venous pressure rises, and the drainage function of the vein is disturbed in volume and direction. Carotid-cavernous co-artery and is such a message between the carotid artery and the cavernous sinus. When arterial blood is sent anteriorly into the eye veins, the ocular symptomatology is determined by venous and arterial stasis around the eyes and orbit, increased pressure in the episcleral veins and lowering of the arterial influx to the cranial nerves inside the cavernous sinus.

Classification of carotid-cavernous anastomosis is based on: etiology (spontaneous and traumatic), hemodynamics (high and low blood flow), anatomy (direct or indirect).

[1], [2], [3], [4],

Symptoms of carotid-cavernous anastomosis

Symptoms directly associated with carotid-cavernous anastomosis:

• aneurysmal noise (train noise);
• pulsating exophthalmos;
• enlargement and pulsation of facial veins and cranial dilatation;
• the phenomenon of blood stagnation in the eyeball, edema of the conjunctiva (chemosis);
• widening of veins, stagnation of blood and vessels of the retina;
• increased intraocular pressure;
• impaired mobility of the eyeball;
• diplopia;
• descent of the upper eyelid (ptosis).

Secondary symptoms due to the duration of existing congestive phenomena in the cavernous sinus, orbit and the venous system of the brain, a. Carotis interna

• atrophy of retrobulbar fiber;
• hemorrhage in the retrobulbar fiber;
• corneal ulcers;
• opacity of the transparent eyes;
• panophthalmitis;
• thrombophlebitis of the veins of the orbit and acute glaucoma;
• atrophy of the optic nerve and blindness;
• bleeding from the vessels of the eyeball, nosebleeds;
• atrophy of adjacent areas of bone tissue;
• complications, which depend on the violation of cerebral circulation (psychosis, dementia, etc.).

Symptoms caused not by the anasthesia itself, but by the reasons that led to its appearance:

• damage to the optic nerve;
• damage to the oculomotor nerves;
• damage to the trigeminal nerve;
• cerebrovascular symptoms associated with the consequences of trauma to the skull and brain.

In the clinical picture of carotid-cavernous anastomosis, 3 periods are distinguished: 

1. Acute (formed by anastomosis and the main symptoms appear).
2. The period of compensation (the increase in symptoms ceases, and they are partially subjected to reverse development).
3. The period of sub- and decompensation (there is a slow or rapid increase in the phenomena that can lead to loss of vision, fatal bleeding, cerebral circulatory insufficiency and mental disorders),

Direct carotid cavernous fistula

This species occurs in 70-90% of cases and represents a direct communication between the carotid artery and the cavernous sinus with a high blood flow velocity due to a defect in the wall of the intracavernous portion of the carotid artery and the result of the following reasons.

• Trauma (75% of cases). Fracture of the base of the skull can lead to a rupture in the intracavernous area of the internal carotid artery with a sudden and dramatic development of symptoms and signs.
• Spontaneous rupture of intracavernous carotid aneurysm or atherosclerotic plaque. The risk group is postmenopausal women with hypertension. The blood flow velocity with spontaneous anastomosis is lower than with traumatic anastomosis, and the symptomatology is less pronounced.

Symptoms of direct carotid cavernous anastomosis

Manifestations may appear after days or weeks after a head injury by a classical triad: pulsating exophthalmos, conjunctival chemosis and noise in the head.

Symptoms usually appear on the side of the anastomosis, but can be bilateral and even contralateral due to the connection between the bloodstreams of both cavernous sinuses through the middle line.

1. changes from the front
   • Ptosis and chemosis.
   • Pulsating exophthalmos in combination with noise and flutter, which disappear when the ipsilateral carotid artery is being pulled around the neck. There may also be noise in the brain.
   • Increase in intraocular pressure due to increased pressure in the episcleral veins and stagnation in the orbit.
   • The ischemia of the anterior segment of the eye is manifested by the edema of the corneal epithelium, the presence of cells and the phlerus in the moisture, atrophy of the iris, the development of cataracts and iris rubeosis.
2. ophthalmoplegia is noted in 60-70% of cases due to damage to the oculomotor nerve in case of trauma, intracavernous aneurysm of the carotid artery, or by the anasthesia itself. The VI nerve most often suffers because of its free location within the cavernous sinus. III and IV nerves are localized in the lateral wall of the sinus and less damaged. Blood-soaked and swollen extraocular muscles also contribute to the limitation of mobility; c) on the fundus there is a stagnant disc of the optic nerve, enlarged veins and intra-retinal hemorrhages due to venous stasis and disturbed blood flow in the retina. Preretinal hemorrhages and vitreous hemorrhages are rare.

Special research methods. On CT and MRI, the prominent upper vein vein and the diffuse thickening of the extraocular muscles are visible. Accurate diagnosis is based on angiography with isolated contrast agent injection into the inner and outer carotid arteries and into the spine blood flow system.

The prognosis is poor: 90% of patients have a significantly reduced vision.

• instant loss of vision can occur if the optic nerve is damaged at the time of injury;
• delayed loss of vision can occur due to various complications: exposure keratopathy, secondary glaucoma, central retinal vein occlusion, ischemia of anterior segment or ischemic neuropathy.

Treatment of direct carotid-cavernous anastomosis

In most cases carotid cavernous anastomosis does not endanger life. The eye suffers the most. Surgical intervention is indicated if spontaneous closure of the fistula as a result of cavernous sinus thrombosis does not occur. Post-traumatic aastomosis closes less often than spontaneously, due to a higher blood flow velocity.

1. Indication: secondary glaucoma, diplopia, intolerable noise or headache, expressed exophthalmos with keratopathy and ischemia of anterior segment.
2. Interventional radiology: the use of a temporary balloon to occlude the hole. The balloon is injected into the cavernous sinus through the opening in the internal carotid artery (arterial path) or through the inferior stony sinus or the superior ophthalmic vein (venous pathway).

[5], [6], [7], [8], [9], [10], [11]

Indirect carotid cavernous fistula

With indirect carotid-cavernous anastomosis (shunt of the dura mater), the intracavernous portion of the internal carotid artery is intact. Arterial blood enters the cavernous sinus not directly, but through the meningeal branches of the external and internal carotid arteries. Due to the weak blood flow, clinical signs are less pronounced than with direct anastomosis, so the condition can be misinterpreted or not noticed at all.

Types of indirect carotid-cavernous anastomosis

• Between the meningeal branches of the internal carotid artery and the cavernous sinus.
• Between the meningeal branches of the external carotid artery and the cavernous sinus.
• Between meningeal branches of both (external and internal) carotid arteries and cavernous sinus.

Causes of an indirect carotid-cavernous anastomosis

• congenital anomaly of development, in which the appearance of symptoms is associated with intracranial vascular thrombosis;
• spontaneous rupture, which can occur with a small injury or stress, especially in hypertensive patients.

It is manifested by the gradual reddening of one or both eyes due to the overfilling of the conjunctival vessels with blood.

Symptoms of an indirect carotid-cavernous anastomosis

• Extended conjunctival and episcleral vessels.
• Increased pulsation of the eyeball, best seen with applanation tonometry.
• Increased intraocular pressure.
• Light exophthalmos are usually combined with mild noise.
• Ophthalmoplegia, more often due to paralysis of the VI pair of cranial nerves.
• The picture of the fundus can be normal or characterized by a mild vein dilatation.

Differential diagnosis is carried out with chronic conjunctivitis, thyroid disease of the eye, glaucoma of other etiology and arteriovenous anomalies of orbit development, which may have a similar picture with dural shunts.

Treatment using "interventional radiology" for the occlusion of feeding vessels, although some patients recover spontaneously.

Treatment of carotid-cavernous anastomosis

Destructive Interventions:

• dressing of carotid arteries on the neck, upper orbital vein;
• turning off the internal carotid artery above and below the level of anastomosis: clipping in the cavity of the skull and bandaging on the neck;
• clipping of the inner carotid artery with subsequent embolization of the anastomosis;
• direct interference with anastomosis (sinus tamponade or clipping of the joints).

Reconstructive interventions:

• embolization of anastomosis according to Brooks;
• occlusion of anastomosis balloon-catheter by the method of F. Sorption of the co;
• embolization using coils (spirals)
• embolization with spinal embolizing composites;
• embolization (spiral-embolizing mixtures).

What is the prognosis of carotid-cavernous anastomosis?

Carotid-cavernous anastomosis has a relatively unfavorable prognosis. Recovery from spontaneous thrombosis of anastomosis occurs only in 5-10% of cases, 10-15% of patients die from intracranial and nasal bleeding, and 50-60% become disabled due to loss of vision and mental disorders.