What is Cavernous Sinus Thrombosis?

Cavernous sinus thrombosis (CST) is a rare and serious condition that can happen due to a facial infection, sinusitis (sinus inflammation), orbital cellulitis (an infection around the eye), throat infection, ear infection, injury, surgery, or conditions that cause blood clots. It’s crucial to identify the symptoms of CST early as it can often cause fever, headache, swelling around the eyes, and difficulty moving the eyes. Even with modern treatments like antibiotics and medications to prevent blood clots, there’s still a significant risk of long-term health effects, such as vision problems, double vision, and stroke.

What Causes Cavernous Sinus Thrombosis?

Cavernous sinus thrombosis is a condition that can either be septic (caused by germs), or aseptic (not caused by germs). Septic cases most often follow infections in the central area of the face, specifically in the ‘danger triangle’ area that stretches from the corners of the mouth to the bridge of the nose. These infections can involve abscesses, cellulitis, sinusitis, dental infections, certain dental procedures, facial surgeries, ear infections, and mastoiditis, sometimes called an infection of the mastoid bone. Aseptic causes, like injuries, surgeries, or pregnancy, are less common than septic causes.

There are many different types of bacteria that can cause cavernous sinus thrombosis. A bacteria called Staphylococcus aureus may cause around two-thirds of the cases, and it’s important to consider that these bacteria may be resistant to a common type of antibiotics known as methicillin. Other typical bacteria include Streptococcus species, pneumococcus, and gram-negative species like Proteus, Hemophilus, Pseudomonas, Fusobacterium, Bacteroides. There are also some gram-positive species like Corynebacterium and Actinomyces. Quite a few of these are anaerobic, meaning they don’t need oxygen to survive.

Fungal infections are less common but can happen, especially in people with weak immune systems. Parasites like toxoplasmosis, malaria, and trichinosis, and viruses like herpes simplex, cytomegalovirus, measles, hepatitis, and HIV can also cause this condition, though it’s rare.

People with weakened immune systems, such as those with uncontrolled diabetes, steroid users, cancer patients, or those undergoing chemotherapy might have a higher risk of not only developing this condition but also experiencing complications from it.

The main risk factors are facial infections, acute sinusitis, and infections around the eyes. A condition called thrombophilia, where your blood clots more easily than normal, can also be a significant risk factor. Women who are pregnant, who’ve just given birth, or who are taking oral contraceptives or hormone replacement therapy might have a higher risk. Certain genetic disorders and acquired disorders can contribute to the risk as well. Other things like severe dehydration, certain kidney conditions, and sickle cell disease could also increase the risk of developing cavernous sinus thrombosis.

Risk Factors and Frequency for Cavernous Sinus Thrombosis

Cavernous sinus thrombosis is a rare condition, making it hard to estimate how many new cases occur each year. Judging by the data we do have, it makes up about 1% to 4% of a similar condition called cerebral venous and sinus thrombosis, which affects two to four out of every million people each year. Given these numbers, we estimate that cavernous sinus thrombosis likely affects around 0.2 to 1.6 in every 100,000 people each year.

It’s not clear whether this condition affects more men or women. Although women are three times more likely to have cerebral venous thrombosis, it doesn’t seem to be the same for cavernous sinus thrombosis. Several researchers have found more cases in men; for example, one study of 88 adults found a 2:1 ratio of men to women, and two other studies also found a slightly higher number of male patients.

Cerebral venous thrombosis, a similar condition, has been found to be more common in children and newborns than in adults. But it’s not certain if this is also true for cavernous sinus thrombosis, or how factors like regular vaccination and the frequent use of antibiotics might affect it.

The number of new cases and deaths from cavernous sinus thrombosis might be decreasing, likely due to the use of antibiotics.

Signs and Symptoms of Cavernous Sinus Thrombosis

Cavernous sinus thrombosis is a serious condition that typically manifests with a range of symptoms. Patients primarily experience a rise in body temperature, headaches, swelling and discomfort around the eye, as well as changes in vision like sensitivity to light, double vision, or even loss of vision. Symptoms can appear suddenly or gradually over a matter of days. It usually starts with one eye, before progressing to the other. Less frequent symptoms could include chills, a rigid or painful neck, numbness in the face, confusion, seizures, stroke-like symptoms, or even a coma.

During a physical check-up, the doctor might note fever (at times in a ‘picket fence’ pattern typical for septic thrombophlebitis), rapid heartbeat, or low blood pressure.

Findings related to the brain, such as altered consciousness, drowsiness or sluggishness, are not unusual. Seizures or stroke-like symptoms are rare, however.

Eye-related symptoms occur in almost all cases. These include swelling around the eye (initially in just one, but usually both eyes eventually), redness of the eyelids, expansion of blood vessels, drooping of the eyelid, protrusion of the eyeball, restricted or painful eye movement, and less commonly, optic nerve swelling. Other less common symptoms include bleeding in the retina, reduced clarity of vision, sensitivity to light, diminished pupillary reflex, and pulsating conjunctiva. Loss of sight can occur in 8-15% of cases.

  • Fever
  • Headaches
  • Swelling and discomfort around the eyes
  • Changes in vision, including double vision, sensitivity to light or even loss of vision
  • The symptoms start with one eye, before progressing to the other eye
  • Other less common signs include chills, a rigid or painful neck, facial numbness, confusion, seizures or stroke-like symptoms

Dysfunction of the sixth cranial nerve is common, causing partial paralysis of the eye muscles and limiting the eye’s ability to move to the side. However, in most cases, this quickly progresses to full paralysis due to the impairment of the third, fourth, and sixth cranial nerves.

Internal paralysis of the eye can cause the pupil to become nonreactive due to paralysis of the iris and ciliary body – it can constrict due to loss of sympathetic nerves or dilate due to loss of parasympathetic nerves.

Horner syndrome (drooping of the eyelid, constriction of the pupil, and absence of sweat) may also be a symptom.

The patient may also exhibit diminished facial sensation due to pressure on the ophthalmic and maxillary branches of the fifth cranial nerve, along with an impaired corneal reflex.

Testing for Cavernous Sinus Thrombosis

The best way to diagnose cavernous sinus thrombosis is by using imaging techniques, such as a CT (Computed Tomography) scan with contrast, or an MRI (Magnetic Resonance Imaging). A highly sensitive CT venogram (CTV) or contrast-enhanced MR venogram (MRV) may be performed. In comparison, a non-contrast CT scan or a time-of-flight MRV may not catch the diagnosis.

Though a non-contrast CT scan isn’t the best tool to diagnose cavernous sinus thrombosis, it might still show signs of the disorder. This could include swollen or widened veins in or around the eyes, a bulging in the area where the cavernous sinus is located, eyes bulging out (exophthalmos), signs of sinus infection in the sphenoid or ethmoid sinuses, and maybe even a tumor (mass) near the sphenoid or pituitary gland.

A contrast-enhanced MRI of the brain might show a bulging cavernous sinus, a higher than usual enhancement of a protective cover of the brain (dura) and absence of normal blood flow.

CTV and contrast-enhanced MRV might be able to detect an enlarged cavernous sinus, unusual bulging of the lateral wall of the cavernous sinus, filling defects after contrast, increased density of orbital fat, a clot in the superior ophthalmic vein or any of its branches leading to the cavernous sinus and more. These scans can also uncover narrowed carotid arteries, enhanced walls of the carotid artery, cerebral infarcts or strokes, internal bleeding in the brain (intraparenchymal hemorrhages), brain abscesses or infections in the brain’s lining (meningitis), and infection in the brain tissue or its covering (cerebritis or empyema). It’s necessary to take a good look at the veins and sinuses in the outer protective layer of the brain (dura) since having multiple clots is common in this condition.

Lab tests may show higher than normal levels of white blood cells, C-reactive protein (a marker of inflammation), erythrocyte sedimentation rate (another inflammation marker) and D-dimer (a protein fragment that indicates clot dissolution). Blood cultures should always be taken and they often test positive.

A lumbar puncture (spinal tap) might be needed to rule out meningitis. This procedure might show high opening pressure and an increase in the number of white blood cells, even if bacteria doesn’t grow in the culture.

Testing for a clotting disorder should be put off until after treatment is done, as the results can be falsely positive if the patient is on anticoagulation therapy.

Treatment Options for Cavernous Sinus Thrombosis

Because of how uncommon this condition is, no set treatment trials have been conducted. Therefore, treatment decisions are guided by expert opinions. Generally, antimicrobial drugs, which fight against microbes, and antithrombotic therapies, which prevent blood clotting, are the main considerations.

The antimicrobial therapy often includes a combination of different drugs to target a variety of microbes. If there is a high resistance to methicillin, a drug used to combat staph infections, vancomycin may be used. A third-generation cephalosporin and metronidazole are also included to target specific microbes, alongside an antifungal treatment with amphotericin B. Experts typically recommend a prolonged period of treatment, usually three to four weeks, or at least two weeks past the point of noticeable improvement.

Many experts suggest the use of blood-thinning medications known as anticoagulants, provided there are no strong reasons not to, such as risk of severe bleeding. Despite a lack of clinical trial support specifically for cavernous sinus thrombosis, a condition where a blood clot forms in the brain’s cavernous sinuses, a look back at past cases suggests that patients’ survival and neurological outcomes may improve with the combination of anticoagulants and antibiotics. This treatment method does have its controversies, as while it may halt worsening blood clot formation and potentially enhance antibiotic effectiveness, it could also lead to bleeding or the spread of infected clots throughout the body.

Moreover, organizations like the Cochrane Collaboration and European Federation of Neurological Societies suggest that anticoagulant use appears to be safe and potentially beneficial in reducing mortality even in the presence of intracranial hemorrhage, a type of bleeding within the skull, in cases of cerebral venous and sinus thrombosis, a somewhat similar condition that also involves abnormal clotting in the brain.

Like in cerebral venous and sinus thrombosis, there isn’t enough evidence to support the use of thrombolysis, a treatment that dissolves blood clots, in cavernous sinus thrombosis.

Corticosteroids, drugs that reduce inflammation, are often prescribed even though no concrete evidence of their effectiveness exists. However, they are necessary in cases of hypopituitarism, a condition that results from decreased secretion of pituitary hormones. Also, no surgical interventions are recommended for the cavernous sinuses themselves. But, in some patients, different types of surgeries might be necessary, such as draining an abscess or relieving pressure on the brain.

Even after antibiotic therapy is discontinued, it’s crucial to continue monitoring the patient.

There are other conditions which have similar symptoms to the cavernous sinus syndrome and painful ophthalmoplegia, namely:

For cavernous sinus syndrome, it can result from non-infectious or non-clot related conditions that press on the cavernous sinus, with tumors accounting for 30% of such cases. These could include:

  • Carotid cavernous fistula, usually diagnosed with enhanced CT scans or MRI that show eye protrusion, enlarged eye veins, a ‘dirty’ appearance behind the eye, and swollen eye muscles.
  • Bone lesions near the sphenoid sinus or sella turcica, which might be due to tumors like metastatic cancer, meningioma, schwannoma, neurofibroma, pituitary tumors, chordoma, chondrosarcoma, melanocytoma, nasopharyngeal carcinoma (the most common primary malignant tumor), or a cavernous hemangioma.
  • Meningioma, a type of brain tumor
  • Sino-orbital aspergillosis, a fungal infection
  • Superior orbital fissure syndrome, another rare condition impacting the eye.

Tolosa-Hunt syndrome is another noteworthy condition involving a non-cancerous but inflammatory lump pushing into the cavernous sinus, causing pain behind the eye, impaired eye movement, nerve issues, and improves with steroid treatment.

Other conditions that can cause painful ophthalmoplegia include:

  • Orbital apex syndrome, an inflammatory condition at the back of the eye affecting various cranial nerves, the superior ophthalmic vein, optic nerve and ophthalmic artery, often resulting in less eye swelling and protrusion but more vision loss than cavernous sinus thrombosis.
  • Orbital cellulitis, an infection of the tissues around the eye.
  • Sarcoidosis, an inflammatory disease that can affect various parts of the body.
  • Syphilis, a sexually transmitted bacterial infection.
  • Tuberculosis, a bacterial infection that primarily affects the lungs.
Frequently asked questions

Cavernous Sinus Thrombosis (CST) is a serious and rare condition that can be life-threatening. It is caused by complications from facial infections, sinusitis, infections around the eye or ear, sore throat, injury, surgery, or a blood clotting disorder. Symptoms include fever, headache, swelling around the eyes, and difficulty moving the eyes.

Cavernous sinus thrombosis affects about 0.2 to 1.6 in every 100,000 people each year.

The signs and symptoms of Cavernous Sinus Thrombosis include: - Fever - Headache - Swelling and pain around the eye - Changes in vision such as sensitivity to light, double vision, and loss of vision - Chills - Stiff neck - Facial numbness - Confusion - Seizures - Stroke-like symptoms - Coma (in severe cases) During a doctor's examination, certain signs may also be noted, such as a fever, rapid heartbeat, or low blood pressure. Eye issues are very common with this condition, appearing in 90% of cases, and can include swelling around the eyes, red eyelids, bulging eyes, restricted or painful eye movement, and in severe cases, vision loss or even blindness. The patient may also show signs of internal paralysis resulting in abnormal pupil reaction, such as pupil constriction or dilation. The sensory examination could reveal decreased facial sensation and impaired corneal reflex.

Cavernous sinus thrombosis can occur from an infection (septic) or from non-infectious causes (aseptic). Septic occurrences often follow infection around the center of the face, especially the area from the corners of the mouth to the bridge of the nose. These infections could be abscesses, cellulitis, sinusitis, dental infections, or complications following certain procedures or surgeries. Less common are aseptic causes, which include trauma, surgery, or pregnancy.

The doctor needs to rule out the following conditions when diagnosing Cavernous Sinus Thrombosis: - Carotid-cavernous fistula - Damage to bones near the sphenoid sinus or sella turcica - Tumors like metastatic cancer, meningioma, schwannoma, plexiform neurofibroma, pituitary adenoma, etc. - Cavernous hemangiomas - Meningiomas - Sino-orbital aspergillosis - Superior orbital fissure syndrome - Tolosa-Hunt syndrome - Orbital apex syndrome - Orbital cellulitis - Sarcoidosis - Syphilis - Tuberculosis

The types of tests that are needed for Cavernous Sinus Thrombosis include: - CT scans (Computed Tomography) with contrast dye - MRI scans (Magnetic Resonance Imaging) - CT venogram (CTV) - Contrast-enhanced MR venogram (MRV) - Blood tests to check for increased levels of white blood cells, C-reactive protein, erythrocyte sedimentation rate, and D-dimer - Lumbar puncture to exclude meningitis - Testing for thrombophilia (blood clotting disorder) after the treatment process is over - Cultures to identify bacteria or other infectious agents - Other imaging tests to assess the veins and sinuses in the outermost membrane of the brain and spinal cord - Follow-up visits after stopping antibiotics.

Cavernous Sinus Thrombosis is primarily treated with antibiotic and anticoagulation therapies. Antibiotic therapy typically includes medications like vancomycin, a third-generation cephalosporin, and metronidazole to cover various types of bacteria. Antifungal treatment with amphotericin B is also recommended. These medications are usually administered intravenously for a long duration, typically three to four weeks or at least two weeks after symptoms improve. Blood thinners like unfractionated heparin or low molecular weight heparin are also suggested for a few weeks to a few months, unless there are contraindications. While there is no specific evidence for cavernous sinus thrombosis, retrospective reviews indicate that using blood thinners with antibiotic therapy may lower deaths and reduce neurological complications. Thrombolysis and steroids may be used in certain cases, and surgeries may be necessary for abscess drainage or other procedures. Follow-up visits are also important even after stopping antibiotics.

When treating Cavernous Sinus Thrombosis, there are potential side effects and risks associated with the treatment. These include: - Bleeding: Blood thinners used in the treatment can increase the risk of bleeding. - Spreading of infected blood clots (septic emboli): Blood thinners may also increase the risk of spreading infected blood clots. - No clear evidence of benefits from steroids: Steroids are often prescribed to reduce inflammation and swelling, but there is no clear evidence of their benefits. - Surgical risks: Some patients may require surgeries such as sphenoidectomy, mastoidectomy, abscess drainage, craniotomy, or ventricular shunt placements, which come with their own risks. - Potential complications: While no clinical trials specifically support the use of blood thinners in Cavernous Sinus Thrombosis, retrospective reviews suggest that they may lower deaths and reduce neurological complications. However, these treatments also come with risks.

The prognosis for Cavernous Sinus Thrombosis (CST) can vary depending on the individual case, but it is a serious condition that can be life-threatening. Even with modern treatments using antibiotics and medicines to prevent blood clotting, there is still a considerable risk of long-term effects such as vision problems, double vision, and stroke. The use and availability of antibiotics may be reducing the occurrence and death rates for CST.

You should see a doctor specializing in neurology or infectious diseases for Cavernous Sinus Thrombosis.

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