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9B. Thrombosis of the intracranial sinuses

Cerebral venous sinus thrombosis (CVST) or cerebral venous thrombosis (CVT) refers to thrombosis of the cerebral veins or cerebral sinuses in the brain. It can be infectious or non-infectious in origin. Thrombosis of the venous drainage of the brain increases the ICP and it can cause brain ischaemia.

The prognosis is good, as 80% recover completely. It more often affects younger adults and females more often than males.

Etiology

  • Non-infectious
    • Hypercoagulable state
      • Contraceptives
      • Blood clotting disorders (Leiden mutation, antiphospholipid syndrome)
      • Polycythaemia
      • Cancer
    • Head trauma
    • Iatrogenic after lumbar puncture
    • COVID-19
    • Certain COVID-19 vaccines (very rare)
  • Infectious (septic cerebral venous sinus thrombosis)
    • Spread from nearby local bacterial or fungal infections
    • Rhinosinusitis
    • Dental infection
    • Acute otitis media, mastoiditis

In many of the cases the patient has an underlying hypercoagulable state.

Clinical features

Symptoms are very variable. They can be acute, subacute, or chronic, but most commonly subacute. Symptoms are non-specific and include headache, symptoms of increased ICP, focal neurological symptoms, and seizures. Headache is the most common symptom, and so it should be should be suspected in patients with subacute development of headache.

If the thrombosis occurs in the superior sagittal sinus, the patient can develop bilateral frontal infarcts, which can cause hemiparesis or paraparesis.

If the thrombosis occurs in the cavernous sinus, the patient can develop palsy of CN III, CN IV, causing ophthalmoplaegia, pupillary alterations, exophthalmos, etc.

Diagnosis and evaluation

Diagnosis is made with CT or MR venography. It can show the thrombosis, or it can show lesions of ischaemia which do not correspond to a single artery territory. The D-dimer is usually high.

It used to be obligatory to screening for blood clotting disorders, but nowadays guidelines only recommend screening in case there is reason to suspect one, like family history, young age, or no apparent risk factors. If infectious etiology is suspected, CRP and blood culture are important.

Treatment

All patients should receive anticoagulants, most commonly LMWH initially and VKA for 3 – 12 months, depend on the risk factors. If a thrombophilia is diagnosed, the patient should be on VKAs for life. If there’s an underlying cause, it should be treated.