Definition
The brain has a network of channels that carry blood away from it and back to the heart. These are called venous sinuses. CVST is when a blood clot forms in the venous sinuses. This keeps the blood from draining out of the brain, causing pressure to build up inside the channels.
If the pressure gets high enough, blood can leak out of the channel and into the surrounding brain tissue. When this happens, it can cause stroke and seizures.
CVST is also a rare type of venous thromboembolism (VTE).
Early recognition and treatment of CVST is important.
Risk factors
CVST affects women more than men due to the hormone oestrogen and its rising levels during pregnancy and after giving birth. The combined oral contraceptive pill and hormonal replacement therapy (HRT) also affect oestrogen levels.
Other risk factors include:
Some people can develop CVST without any risk factors.
Symptoms
The symptoms of CVST can vary widely from person to person, but may include:
DIAGNOSIS
If CVST is suspected, your doctor will carry out the following tests:
These imaging tests help your doctor to see if there is a blood clot causing a blockage in your brain.
TREATMENT
CVST is a rare condition. Treatment usually involves the use of anticoagulant (or blood thinning) medications to stop the clot growing and to stop new clots from forming. If there is an underlying cause to the CVST (such as head injury or an infection) this will be treated too.
Anticoagulant medications carry a risk of increased bleeding, so patients are watched very closely when they first start taking them. Some CVST patients already have bleeding in the brain by the time they begin treatment – this is due to a blood clot causing pressure to build in their sinus. Anticoagulant medications may still be the right treatment, because the main problem of that bleeding is the blood clot, and treating the blood clot is the priority.
In cases of severe CVST that have not improved with anticoagulant medication, neurologists may recommend using clot-busting medication to the site of the clot (thrombolysis) or physically removing the clot (thrombectomy). However, the evidence on these methods is unclear.
Once you have been discharged from hospital, you may need to continue taking anticoagulant medication. Your doctor will advise you.
Sometimes there can be complications from CVST, such as seizures. If you have seizures, your doctor or neurologist may prescribe antiepileptic medication.
For more information on how to reduce the risk of further blood clots, see thrombosis.
