Cerebral Venous Sinus Thrombosis

Clotting of dural venous sinus blood, causing raised ICP and intracranial symptoms. Very rare — 3–4 per million.

Risk factors

Thrombophilia (factor V Leiden, protein C deficiency, antithrombin deficiency); nephrotic syndrome; chronic inflammatory disease (SLE, IBD, Behçet disease); pregnancy/postpartum; COCP use; polycythaemia; sickle cell disease; dehydration (infants/children); trauma to vessels; association with intracranial or maxillofacial infection.

Clinical features

• Headache in 90% — worsens over several days, but can be sudden (thunderclap); may be the only symptom.
• Stroke-like limb symptoms, depending on clot extent and ICP elevation.
• Seizures — 40% if untreated (mostly focal, can generalise to tonic-clonic).
• Altered mental status — confusion/disorientation, especially in the elderly, who may have no other symptoms.
• Papilloedema, loss of consciousness, Cushing’s triad (with severe ICP rise).

Investigations

CT brain; MR/CT venography or angiography. A positive D-dimer can support the decision to pursue CT/MRI in younger patients (low specificity but useful as a “don’t rule out” trigger).

Treatment

• Anticoagulation — initially heparin/LMWH in hospital, then long-term anticoagulation. Direct oral anticoagulants (dabigatran, or rivaroxaban/apixaban) are now a well-evidenced alternative to warfarin, with comparable efficacy and lower major haemorrhage risk; duration is typically 3–12 months depending on provoked/unprovoked status, individualised with specialist input. Anticoagulation is still appropriate even with extensive haemorrhage on imaging, provided no other bleeding risk is identified.
• Anticonvulsants for seizure control.
• Reserved for significantly raised ICP threatening vision or causing compressive symptoms: thrombolysis, decompressive craniectomy, or therapeutic lumbar puncture to reduce ICP.

Prognosis

A 2004 study found up to 57% of patients recover fully, with ~29%/2.9%/2.2% having minor/moderate/severe residual impairment; 8.3% mortality. Overall prognosis is generally more favourable than other causes of intracranial haemorrhage or stroke, with around 90% of patients achieving good functional recovery.