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.
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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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.
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:
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.
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.
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 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:
Because cavernous sinus thrombosis is a potentially life-threatening condition that can progress quickly, your provider may begin treatment before confirming your diagnosis.
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:
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:
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.
Seek care immediately if you experience the following symptoms:
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.
Last reviewed by a Cleveland Clinic medical professional on 07/18/2022.
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