Cerebral Venous Sinus Thrombosis

Question 1

What is the pathophysiology behind CVST?

Answer 1

• Usually a dural venous sinus thrombosis, either sagittal (50% of IVT) or transverse (35%). Other sites include the cavernous sinus, typically post-infection.
  
  • Can progress to cortical vein thrombosis (CVT), which can then progress to venous infarction as arterial flow is blocked i.e. a stroke. Consider IVT as a cause of stroke if an infarction crosses arterial boundaries.
  • The blockage often causes ↑ICP, and patients may present with this alone. Consider it as a differential in idiopathic intracranial hypertension.

Question 2

What are the causes/risk factors for CVST?

Answer 2

• Common:
  
  • Pregnancy or OCP use, hence common in women 20-35 years old.
  • Others: thrombophilia, trauma, hypovolaemia, brain tumour, recent LP.
• Rarer:
  
  • Systemic disease: cancer, IBD, SLE, polycythaemia rubra vera, nephrotic syndrome, homocystinuria.
  • Infection: meningitis, ENT infection, TB, cerebral abscess.
• Idiopathic in 25%.

Question 3

What are the signs and symptoms associated with CVST?

Answer 3

• Headache (90%), usually developing over days, but can be thunderclap (especially in CVT).
  
  • Seizures (40%), usually focal.
  • Others: nausea and vomiting, papilloedema, impaired vision, ↓level of consciousness.
  • Stroke-like focal signs, commonly due to CVT.
  • Cranial nerve palsies from local compression or CN6 palsy due to ↑ICP.
  • Mastoid pain in transverse sinus thrombosis.
  • Cerebellar signs in sigmoid sinus thrombosis.
  • In elderly may present only with altered mental status.

Question 4

Which investigations should be performed in suspected CVST?

Answer 4

• Contrast CT or MR venography: absence of sinus, empty delta sign.
  
  • LP: may show ↑opening pressure, RBCs, and/or xanthochromia.
  • Thrombophilia screen.
  • Autoantibody screen for anti-phospholipid syndrome.

Question 5

How is CVST managed?

Answer 5

• Heparin or LMWH.
  
  • Consider warfarin long term.
  • Anticonvulsants if seizures occur.

Question 6

Which complications can occur with CVST and what is the prognosis for these patients?

Answer 6

Acute: ↑ICP can lead to intracranial haemorrhage and transtentorial herniation.
Long term: epilepsy, pyramidal symptoms.
* 10% mortality.