Cerebral Venous Sinus Thrombosis
Background
Pathophysiology
- 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.
Causes and risk factors
- 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%.
Signs and symptoms
- 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.
Investigations
- 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.
Management
- Heparin or LMWH.
- Consider warfarin long term.
- Anticonvulsants if seizures occur.
Complications and prognosis
- Acute: ↑ICP can lead to intracranial haemorrhage and transtentorial herniation.
- Long term: epilepsy, pyramidal symptoms.
- 10% mortality.
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