Cavernous sinus thrombosis is a blood clot in the cavernous sinuses. It can be life-threatening.

The cavernous sinuses are hollow spaces located under the brain, behind each eye socket. A major blood vessel called the jugular vein carries blood through the cavernous sinuses away from the brain.

A blood clot can develop when an infection in the face or skull spreads to the cavernous sinuses. The blood clot develops to prevent the infection spreading further, but it can restrict the blood flow from the brain, which can damage the brain, eyes and nerves running between them. Sometimes, clots can develop without infection.

Read more about the causes of cavernous sinus thrombosis.

Symptoms of cavernous sinus thrombosis include:

  • a sharp and severe headache, particularly around the eye
  • swelling and bulging of the eye(s) and the surrounding tissues
  • eye pain that's often severe
  • double vision

Read more about the symptoms of cavernous sinus thrombosis.

When to see your GP

Contact your GP if you experience a persistent and severe headache you haven't had before, or if you develop eye pain or swelling of one or both eyes.

While it's highly unlikely to be the result of cavernous sinus thrombosis, a persistent headache usually needs to be investigated.

After an examination, you may be referred for tests, including a computerised tomography (CT) scan, a magnetic resonance imaging (MRI) scan and blood tests.

Treating cavernous sinus thrombosis

Cavernous sinus thrombosis needs treatment in hospital.

If there's infection, the main treatment is antibiotics, which are usually given through a drip into a vein in the arm. This treatment usually lasts at least three to four weeks.

Despite some uncertainty about their use, you may also be treated with anticoagulant medication (to dissolve and prevent blood clots) or steroid medication (to reduce any swelling).

Most people will need to stay in hospital for several weeks or even months before they're well enough to go home.

Read more about treating cavernous sinus thrombosis.

Complications of cavernous sinus thrombosis

Cavernous sinus thrombosis is a very serious condition. Even with prompt treatment, as many as one in three people with the condition may die.

Around 1 in 10 people who survive will develop long-term health problems due to damage to their brain, such as persistent headaches and fits, or some degree of vision loss

Read more about the complications of cavernous sinus thrombosis

Who's affected?

It's difficult to say exactly how many people are affected by cavernous sinus thrombosis, but it's thought to be very rare.

The condition affects people of all ages and tends to be more common in women than men. This may be because pregnancy and taking the oral contraceptive pill can make women more vulnerable to blood clots.

Page last reviewed: 13/05/2015

Next review due: 13/05/2017