5th August 2024

Cerebral venous sinus thrombosis

The pathophysiology of CVST (cerebral venous sinus thrombosis) is not fully understood, however it is thought to be caused by the thrombosis of cerebral veins or dural sinuses leading to blockages in the drainage of blood in the brain. Reduced CSF absorption in the brain is also thought to play a role. These mechanisms ultimately lead to an increase in intracranial pressure.

Risk factors are female sex, prothrombotic conditions, pregnancy and the puerperium, oral contraceptives, cancer, ENT infections and head injury.

It can be difficult to diagnose as it can present in a variety of ways. The headache can be acute, subacute or chronic and does not follow a specific pattern. Diagnosis relies on an MRI brain and MR venogram or CT brain and venogram.

The three key clinical presentations to look for are:

1. Intracranial hypertensive syndrome: headache, visual changes and papilloedema.
2. Focal neurological deficits: seizures, hemiparesis or dysphasia.
3. Encephalopathy: delirium, multiple neurological deficits or coma.

It should also be noted that isolated thrombosis of the different sinuses or veins will present differently:

• Cavernous sinus thrombosis presents with ocular signs and is generally preceded by an ear, sinus or tooth infection.
• Lateral sinus thrombosis, a rare complication of untreated otitis media, usually presents with a headache or isolated intracranial hypertension but focal neurological deficits can be present (usually CN [cranial nerve] VI palsy).
• Sagittal sinus thrombosis presents with motor deficits or seizures. It is associated with the use of oral contraceptives and is also a rare complication of meningitis.

After diagnosis, antithrombotic treatment with low molecular weight heparin is started. Most patients are then given dabigatran or warfarin for a minimum of 3 months.

With treatment, the prognosis is usually quite good, with studies reporting a complete recovery in around 80% of patients. However about 5% unfortunately die during the acute phase of the disease.