Carotid cavernous fistula is a pathological communication between the cavernous part of the internal carotid artery and the cavity of the cavernous sinus. The disease develops as a consequence of a skull injury or spontaneously against the background of existing structural and functional changes in the walls of blood vessels. Pathology is manifested by pulsating exophthalmos, massive swelling of the eyelids and conjunctiva, progressive loss of vision and limited mobility of the eyeball. Ophthalmoscopy, transcranial ultrasound, carotid angiography with contrast are used for diagnosis. Radical treatment requires endovascular surgery to turn off the pathological anastomosis from the bloodstream.
ICD 10
Q28.2 Arteriovenous malformation of cerebral vessels
General information
Carotid cavernous fistula (CCF) was first described in 1813 by the English surgeon B. Travers under the name “pulsating exophthalmos”. The true prevalence of the disease is unknown, which is also due to the difficulties of diagnosis and the lack of awareness of primary care doctors about this syndrome. Carotid cavernous fistula is more common in men. CCF can cause critical disorders of intracranial blood flow and is a serious problem for practical neurosurgery.
Causes
More than 75% of cases of carotid cavernous fistula develop as a result of traumatic brain injury: bruising and concussion of the brain, damage to the eye socket. The more severe the TBI, the higher the chances of developing a vascular anomaly, which often goes unnoticed against the background of the general critical condition of the patient. The remaining 25% of cases are spontaneous ruptures of the artery, which occur against the background of cerebral atherosclerosis, arterial hypertension.
Pathogenesis
The development of the carotid cavernous fistula is facilitated by the features of the anatomy of the carotid artery. The cavernous part of the vessel has a thin wall due to the underdevelopment of muscle and elastic fibers, so it is easily injured even from minor mechanical impact. The second predisposing factor is the sharp bends of the artery, which contribute to hydraulic shocks of blood, especially in conditions of high blood pressure.
When the arterial wall is damaged, blood is sent at high speed into the cavity of the cavernous sinus. Due to the large pressure drop, there is a retrograde outflow of blood through the draining veins, resulting in stagnation in the eye socket and the nearby part of the brain. At the same time, the blood supply to the anterior and middle cerebral arteries worsens, and chronic cerebral hypoxia develops.
Classification
According to the clinical course, an acute period of the disease is distinguished, which passes into the expanded stage of CCF. It, in turn, is divided into compensated, subcompensated and decompensated forms. In practical neurosurgery, the angiographic classification of the cavernous sinus anastomosis is of the greatest importance, according to which there are 2 types of vascular anomalies:
- Type A – high-speed. These are typical carotid-cavernous anastomoses of a large flow, which are associated with traumatic or spontaneous rupture of the carotid artery. They are manifested by significant hemodynamic disorders.
- Type B – low-speed. These include dural arteriovenous malformation, in which the carotid-cavernous fistula is formed indirectly through the branches of the internal and external carotid artery.
Symptoms
Most cases of pathology develop subacute, with the exception of spontaneous ruptures of the vessel against the background of a hypertensive crisis or severe trauma. The main manifestation of the carotid cavernous fistula is pulsating exophthalmos, in which the eyeball protrudes more than 1 cm from the normal position. It is accompanied by swelling of the eyelids and red-purple color of the conjunctiva. During external examination, there is also an expansion of veins in the eyelids and forehead.
The symptoms are complemented by severe pain in the eye socket and the lower part of the forehead. Another painful sign of a carotid-cavernous fistula is a noise in the head, which occurs synchronously with the pulse. Constant and strong sound sensations, resembling the noise of a steam locomotive, exhaust patients, cause psychoemotional disorders. Visual disturbances are represented by strabismus, diplopia, restriction of eye movements.
With a long-term disease, many patients complain of cognitive impairment: memory loss, slowing down the speed of thinking, deterioration of mental performance. Such manifestations are associated with chronic hypoxia of the brain. Constant tinnitus, visual disturbances and external changes in the eyeball cause severe psychoemotional disorders up to depression and acute psychosis.
Complications
Hemodynamic disorders in the orbital zone cause an increase in intraocular pressure and the formation of glaucoma, which leads to a persistent decrease in vision. Ophthalmohypertension in combination with dilation of the fundus veins and compression of nerves can cause blindness. The enlarged cavernous sinus squeezes not only the oculomotor nerves, but also the first branch of the trigeminal nerve, causing disturbances in the production of lacrimal fluid and sensitivity disorders.
When the cerebral blood flow is stolen, there is a risk of developing dyscirculatory encephalopathy, ischemic stroke. Intracranial hemorrhages are recognized as the most dangerous consequence of carotid cavernous fistula. They occur when the wall of the cavernous sinus or congestive cerebral veins ruptures. Hemorrhagic complications are the main cause of death in patients with CCF.
Diagnostics
Patients with suspected carotid cavernous fistula will need to consult an ophthalmologist and a neurosurgeon. The scope of the examination depends on the patient’s well-being, in the acute period, diagnosis is carried out in parallel with urgent medical measures. Valuable information is obtained by an external examination of the affected eye, clarifying the conditions of the development of the disease and the presence of head injuries in the anamnesis. The following methods are used to confirm the diagnosis:
- Ophthalmological examination. Visual examination of the eyeball determines the eversion of the eyelids due to severe edema, chemosis, brown-red conjunctiva, which looks like granulation tissue. According to ophthalmoscopy, the expansion and swelling of the veins, edema of the optic disc, spot hemorrhages in the retina are determined.
- Transcranial Dopplerography. Ultrasound examination is used as a screening method to detect arteriovenous bypass surgery in the area of internal carotid arteries. According to the results of ultrasound, it is possible to detect violations of venous outflow in the system of basal veins of the brain and orbital veins.
- Angiography. X-ray contrast examination of blood vessels is used to determine the type, localization and size of the anastomosis, to detect retrograde arterial blood flow. According to angiography, the degree of theft of cerebral vessels, the presence of collateral compensation of blood flow disorders are studied.
- CT scan of the brain. Neuroimaging is used in cases of suspected intracranial hemorrhages, compression of nerve structures and other complications of the disease. Computed tomography is also the main method for the diagnosis of TBI, against which a carotid-cavernous fistula has arisen.
Differential diagnosis
Given the rarity of the disease, when making a diagnosis, it is necessary to exclude other types of vascular anomalies:
- dural venous fistula;
- arteriovenous malformation of the eye socket;
- carotid-jugular anastomosis.
Typical neuro-ophthalmological symptoms require differential diagnosis with Tolosa-Hunt syndrome, which is characterized by damage to the oculomotor nerves and is manifested by painful ophthalmoplegia.
Treatment
The only radical method of correction of vascular abnormality is surgical intervention. In neurosurgery, there are different techniques of surgery, which are selected taking into account the anatomical characteristics of the carotid cavernous fistula, the severity of the disease, the general condition of the patient. Intravascular balloon occlusion, which turns off the CCF from the general blood flow, is recognized as the most effective.
The operation is characterized by low traumatism, gives a quick and pronounced clinical effect. Immediately after its completion, patients stop experiencing noise in the head, their exophthalmos and stagnant phenomena on the fundus gradually decrease. After 1-2 weeks, the restoration of visual function and eye mobility begins, although in many patients this process is not completed until the end. Radical surgical extraction is more often achieved with type A anastomoses .
Prognosis and prevention
Carotid cavernous fistula is characterized by an unfavorable course: complete recovery occurs only in 5-10% of patients. The remaining patients have persistent and irreversible vision loss, mental disorders. Without timely assistance, up to 15% of cases of CCF are fatal. Prevention of the disease is to reduce the risk of domestic, road traffic and sports injuries.
