Cavernous Sinus Thrombosis

Cavernous sinus thrombosis is a rare blood clot that can form in response to an infection in your face or head. It’s fatal in about 1 in 3 cases. Early symptoms include a severe headache, followed by swelling or bulging in one or both eyes. This condition requires immediate treatment.


What is cavernous sinus thrombosis?

Cavernous sinus thrombosis is a rare, potentially life-threatening blood clot in your cavernous sinuses. Your cavernous sinuses are located behind your eyes, beneath your brain. Multiple veins, including a major one called the jugular vein, run through your cavernous sinuses. They help drain the blood from your brain and face. If a blood clot forms in one of these veins (often in response to an infection), the clot can restrict blood flow from your brain.

Cavernous sinus thrombosis can cause long-term damage to your brain, eyes and nerves. Without prompt treatment, it may result in death.


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How common is cavernous sinus thrombosis?

Cavernous sinus thrombosis is so rare that it’s difficult to predict how many cases happen yearly. Cases have declined substantially in the modern era, thanks to the widespread availability of antibiotics. Antibiotics can cure infections that may have otherwise caused a blood clot.

Symptoms and Causes

What are the symptoms of cavernous sinus thrombosis?

One of the earliest symptoms of cavernous sinus thrombosis is a severe headache that gets worse even with pain medicine. The pain may feel sharp immediately or worsen over several days. The pain may feel especially pronounced around or behind one or both eyes.

Symptoms are related to pressure build-up in your cavernous sinuses and can worsen rapidly. Signs to look for include:

  • Severe, sharp headache.
  • Bulging or swelling around one and then both eyes.
  • Droopy eyelids.
  • Pain when you try to move one or both eyes.
  • Inability to move one or both eyes.
  • Blurred vision.
  • Seeing double.
  • Facial numbness.
  • Fever.
  • Seizures.

Untreated cavernous thrombosis worsens until symptoms progress to confusion and sleepiness. A coma and death often follow. It’s crucial to receive treatment before the condition reaches this point.


How quickly does cavernous sinus thrombosis occur?

Cavernous sinus thrombosis may show up five to 10 days after having an untreated infection in your face or skull. The first sign of a clot is usually a headache. Symptoms related to your eyes (bulging, swelling) may happen shortly after the headache or gradually develop.

What causes cavernous sinus thrombosis?

Cavernous sinus thrombosis is most often a complication of a bacterial infection in your face or skull. The blood in your cavernous sinus veins clots to prevent the infection from spreading. Instead of stopping the spread, however, the clot traps the infection. It prevents blood from flowing away from your brain. The blood creates pressure in your cavernous sinuses, causing common symptoms like headache and eye pain.

Infectious causes include:

In up to 70% of cases, Staphylococcus aureus bacteria cause the infection. Other types of bacteria and some fungi may also cause infections that lead to cavernous thrombosis. There are also a few documented cases of cavernous sinus thrombosis related to COVID-19 infection.

Rarely, the clot forms in response to a head injury instead of an infection.


Diagnosis and Tests

How is cavernous sinus thrombosis diagnosed?

Diagnosis can be tricky, as cavernous sinus thrombosis shares symptoms with more common conditions, like an eye infection or a migraine.

Still, your healthcare provider may suspect cavernous sinus thrombosis based on your symptoms, especially if you currently have or recently had a sinus infection.

Your diagnosis may include any of the following tests or procedures:

  • Imaging. MRI and CT scans allow your provider to identify clots in your cavernous sinuses. An MRI with venogram (MRV) is the most sensitive imaging procedure for this diagnosis. During an MRV, your provider will insert a contrast dye into your vein to make it easier to see blood flow during the MRI.
  • Bacteria culture test. Your provider may check your blood or other body fluids (for example, sinus fluid) for signs of bacteria or other pathogens that are causing your infection.
  • Spinal tap (lumbar puncture). A lumbar puncture can show if the infection has spread to your brain, as with meningitis. Meningitis is a complication of cavernous sinus thrombosis. During the procedure, your provider inserts a needle into your low back to collect a sample of spinal fluid. The fluid is tested for bacteria and other signs of infection.

Because cavernous sinus thrombosis is a potentially life-threatening condition that can progress quickly, your provider may begin treatment before confirming your diagnosis.

Management and Treatment

How is cavernous sinus thrombosis treated?

Cavernous sinus thrombosis requires immediate treatment. You’ll likely be admitted into an intensive care unit (ICU) so your provider can monitor you closely. Treatments include:

  • Antibiotics. Your provider will begin antibiotic treatment through an IV to clear the infection that’s causing the clot. Treatment is time-sensitive, so you’ll likely receive antibiotics before diagnostic tests confirm what pathogen (bacteria, fungus, etc.) is causing your infection. To be safe, you’ll receive broad-spectrum antibiotics that can kill various bacteria — especially S. aureus. Treatment may continue in the hospital for several weeks.
  • Anticoagulants. You may need medicines that thin your blood, like heparin, to dismantle the clot and prevent new clots from forming. You may need to take anticoagulants several months after your initial treatment.
  • Corticosteroids. Your provider may prescribe steroids to reduce the inflammation causing pressure in your sinuses. If so, you’ll receive them after antibiotic treatment.
  • Sinus surgery. You may need surgery to drain any fluid build-up related to your infection and blood clot.

Outlook / Prognosis

What can I expect if I have cavernous sinus thrombosis?

Before antibiotics, cavernous sinus thrombosis nearly always resulted in death. Now, more than 70% of people with cavernous sinus thrombosis survive.

Still, many people experience complications. For instance, just under 20% of people who survive cavernous sinus thrombosis have vision problems and nerve damage. Other complications include:

Having cavernous sinus thrombosis may lead to other dangerous clots, like clots in your legs (deep vein thrombosis), lungs (pulmonary embolism) or brain (stroke).

Speak with your provider about the likelihood your condition will lead to complications. Ask about the warning signs so you can prevent complications whenever possible.

Living With

When should I seek care?

Seek care immediately if you experience the following symptoms:

  • Sharp headache that doesn’t improve with headache medicine.
  • Headache that worsens when you lie on your back or bend down.
  • Eye pain or swelling that affects one eye or both.
  • Feeling sick, weak or drowsy.
  • Shortness of breath.
  • Fever.

What questions should I ask my doctor?

  • What treatments will I need?
  • How long will I need treatment?
  • What’s the likelihood I’ll experience complications related to the clot? Are they preventable?
  • What adjustments will I need to make to my lifestyle in response to complications?
  • Will I need additional medications or therapies to address the complications?
  • What’s the likelihood that I’ll have this condition again?

A note from Cleveland Clinic

Learning something as common as a sinus infection can potentially lead to a life-threatening clot may feel terrifying. Cavernous sinus thrombosis — a blood clot that can form in response to an infection in your face or head — is incredibly rare. But there’s a much greater chance that your headache or eye pain is a sign of a less concerning condition. Still, it’s always a good idea to treat infections promptly. Receiving prompt treatment can potentially prevent a more severe condition.

Medically Reviewed

Last reviewed on 07/18/2022.

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