A carotid cavernous sinus fistula is a vascular abnormality. This creates an unnatural connection between the venous plexus located there and a cervical artery behind the eye.
What is a carotid and cavernous sinus fistula?
A carotid cavernous sinus fistula (CSCF) is when an abnormal connection forms between the venous plexus behind the human eyes and a cervical artery. The cavernous sinus is understood to be a small vein space behind the human eyes. It contains the veins, whose function is to transport the blood back out of the brain and face.
There are two paired internal and external carotid arteries (carotid arteries) on each side of the neck. They supply the brain with blood. Occasionally a small tear will form in the carotid arteries. If this process happens in the veins of the cavernous sinus, a smaller canal can develop between them, which doctors call a fistula. This fistula works by diverting blood from an artery towards a vein.
Near the cavernous sinus are the cranial nerves that control the movements of the eyes. Their tasks also include perceiving sensations in certain areas of the head and face. With the formation of a fistula, there is a risk that the pressure in the cavernous sinus will increase, which results in a compression of the nerves. This threatens functional impairments, which are noticeable through various complaints.
Carotid and cavernous sinus fistulas are divided into two different types. These are the direct and the indirect fistula. Direct CSCF is a connection between some internal areas of the carotid artery and the veins that are in the interior of the cavernous sinus. Usually this leads to an increased blood flow rate. This CSCF variant is the most common.
In the case of an indirect carotid-cavernous sinus fistula, it arises between the cavernous sinus veins and the branches of the carotid arteries within the membranes that envelop the brain. A typical feature of this form is the low blood flow velocity. Direct carotid-cavernous sinus fistulas are caused by injuries or accidents in which a rupture of the carotid artery wall occurs. These are mostly caused by falls, car accidents or violence. But a surgical intervention can also be responsible for the development of a direct fistula.
The formation of indirect carotid-cavernous sinus fistulas is usually quite abrupt. It has not yet been possible to determine what causes them. However, special risk factors are known. These include high blood pressure, connective tissue diseases, arteriosclerosis, as well as pregnancy and the birth process.
Symptoms, ailments & signs
The symptoms of a carotid and cavernous sinus fistula depend on its shape. Indirect fistulas, for example, usually cause less pronounced symptoms, which is due to the relatively low speed of blood flow. In the case of direct fistulas, however, the symptoms are more intense.
In both forms of carotid cavernous sinus fistula symptoms show as red eyes, a protrusion and pulsation of the eye, a protruding eye of vision loss and double vision. Other possible complaints are ringing in the ears (tinnitus), a buzzing in front of the eye that can be heard, weak eye movements, facial pain, nosebleeds and headaches.
Because the arteries no longer supply the brain with optimal blood supply, there is a risk of complications such as multiple ischemic seizures. In addition, the risk of a cerebral blood clot increases. Further complications are a rupture of the cavernous sinus or the formation of glaucoma due to a disturbance of the aqueous humor outflow.
Diagnosis & course
To diagnose a carotid-cavernous fistula, the doctor will do a careful examination of the affected eye. In some cases, it may also be necessary to examine the cavernous sinus and neighboring blood vessels. For this purpose, a sonography (ultrasound examination), a computed tomography (CT) or a magnetic resonance tomography (MRT) are carried out.
Angiography can also be performed to confirm the diagnosis. The doctor injects a contrast medium into the patient’s blood vessels, which can be seen on the following X-ray images. This is followed by an X-ray examination of the neck and head. If a carotid-cavernous sinus fistula is treated properly, a noticeable improvement in symptoms usually occurs after a few days or even hours.
Most patients are symptom-free again after about six months. However, in the case of direct CSCF, which is associated with pronounced symptoms, not every patient fully recovers.
The symptoms and complications depend to a relatively large extent on the severity of the carotid-cavernous sinus fistula. In most cases, there is a strong reddening of the eye, which is not due to a foreign body. The patient also suffers from a throbbing eye, which can be associated with headaches and other facial pains.
The function of the eyes is also restricted, which can lead to blurred vision or double vision. The eyesight itself can also be reduced by the carotid-cavernous sinus fistula. It is not uncommon for tinnitus and nosebleeds to occur. The everyday life of the person affected is severely restricted by the carotid-cavernous sinus fistula. Concentration disorders and often a lack of sleep also occur.
Treatment is not necessary in all cases; the seal often loosens by itself without a doctor having to intervene. However, if the symptoms and complaints are relatively severe, surgery can also be carried out. The operation proceeds without complications. So that the eyes do not dry out, the person concerned is usually also dependent on eye drops. After the treatment, the symptoms in the eyes and face disappear completely.
When should you go to the doctor?
If, after an injury or an accident, eye complaints such as redness, pulsation and pain as well as loss of vision are noticed, the attending physician should be informed in any case. A carotid-cavernous sinus fistula manifests itself, among other things, by ringing in the ears, facial pain, headache and nosebleeds. In the event of these warning signs, a doctor should be consulted in any case, who can clarify the symptoms and, if necessary, treat them directly.
At the latest when the CSVF leads to restrictions in the everyday life of the person concerned, it must be treated. A medical emergency occurs when the first warning signs of a cerebral blood clot or a stroke appear – in these cases you should call the emergency services immediately. Complications such as the development of glaucoma also need to be clarified immediately.
Surgery may be needed if symptoms are severe. After that, regular follow-up examinations are indicated, during which the doctor makes sure that there are no complications. In addition to the responsible general practitioner, a specialist in eye diseases can also be visited with a carotid-cavernous sinus fistula.
Treatment & Therapy
Indirect carotid and cavernous sinus fistula does not always require therapy. In numerous cases, the fistula closes automatically. However, if the symptoms are severe or if the symptoms worsen, surgery may be necessary.
In such cases, endovascular embolization is usually performed. The surgeon inserts a narrow tube into an inguinal artery, which he pushes towards the fistula. Once the tube has reached the fistula, the abnormal connection is locked using metal coils.
But there are other therapeutic options such as the administration of medication. These include special means that have a reducing effect on the pressure in the eye. It can also be useful to administer eye drops that counteract dryness of the organ of vision. The last treatment option is to surgically close the eyelid with stitches. In this way the surface of the eye is protected. After a successful course of therapy, the doctor removes the sutures again.
Outlook & forecast
The carotid-cavernous fistula has a favorable prognosis. Due to the self-healing powers of the human organism, in many patients a natural closure of the fistula occurs without further intervention. Spontaneous healing follows after a few days of the appearance of the fistula. No further treatment or additional medical care is required. There are also no after-effects.
If the self-healing process does not occur, various complaints develop. These reduce the quality of life for the duration of the treatment, but are not permanent. The fistula is usually separated or sealed off by embolization. The procedure is routine and involves few risks.
Normally, the patient can cope with it. The disturbed processes then regenerate and the patient is free of symptoms. Many patients receive follow-up treatment by giving them eye drops or other medicines. These support the healing process and can be discontinued after a few days or weeks.
In rare cases, temporary closure of the eyelid is initiated as part of the treatment process. As soon as the therapy is finished, the closure is removed and there are no symptoms. The carotid-cavernous fistula can recur at any time during life. The prognosis is also favorable if the fistula recurs.
There are no known effective preventive measures against a carotid-cavernous sinus fistula.
A carotid cavernous sinus fistula usually does not always require direct follow-up care. In many cases, the fistula does not have to be treated surgically, as it does not lead to any particular symptoms and does not have a negative impact on the life of the person concerned. Only in rare cases does the fistula require surgical intervention.
As after any surgical procedure, the person affected has to take it easy and give the body plenty of rest. Above all, the eyes must be spared. Eye drops are also often given to relieve the symptoms or to speed up healing after the operation. In severe cases, the eyelids are completely closed with surgical stitches and opened again after healing.
The patient should avoid and relax in stressful situations with a carotid cavernous sinus fistula. Various techniques can also help here. Vitamin K also has a very positive effect on the healing of the fistula, although a healthy diet can accelerate this significantly. People should avoid anti-coagulants and antibiotics if they can. Carotid-cavernous sinus fistula generally does not have a negative impact on life expectancy.
You can do that yourself
Self-help and recommended adjustments to direct or indirect carotid and cavernosis sinus fistula depend on the intensity and causation of the symptoms.
If the symptoms of a direct connection between the arterial vessels of one of the carotid arteries and the venous vascular system in the area of the cavernous sinus are weak to moderate, low arterial blood pressure promotes self-healing. This means that the fistula, which creates the connection between the two vascular systems while bypassing the capillary structures, can close again on its own.
In order to keep the systolic blood pressure as low as possible, chronic stressful situations should be avoided in everyday life, which have the effect of increasing blood pressure by activating the sympathetic nervous system and constricting certain arteries. Practicing relaxation techniques such as meditation, yoga, and endurance sports can also help the fistulas to self-seal.
In addition, care should be taken in the diet that the food sufficient vitamin K contained. The fat-soluble vitamin K has a decisive influence on the blood’s ability to clot. Vitamin K is found in many natural foods such as spinach, Brussels sprouts, and chives, as well as many other vegetables. Often, a lack of vitamin K is caused by antibiotics or other drugs.
Unfavorable effect on the self-healing chances of carotid-cavernous fistula is acting anticoagulant, because they hinder the process of physiological closure of one or more fistulas.