Cerebral venous sinus thrombosis
Description
- Thrombosis of dural sinuses and/or cortical veins
- Two mechanisms, often coexisting:
- Venous outflow obstruction -> venous congestion -> vasogenic + cytotoxic oedema -> venous infarction, often haemorrhagic
- Impaired CSF absorption at arachnoid granulations -> inc ICP
- Venous infarcts do not respect arterial territories, cross them, and bleed - a "stroke" with haemorrhage in an odd distribution in a young patient is CVST until proven otherwise
Sites
- Superior sagittal sinus ~60% (bilateral parasagittal infarcts, leg weakness)
- Transverse/sigmoid ~40-50% (often with mastoiditis/otitis)
- Deep venous system (straight sinus, internal cerebral veins, vein of Galen) ~10% - bilateral thalamic/basal ganglia changes, coma. Worst prognosis
- Cortical vein alone - focal deficit + seizure
- Cavernous sinus - proptosis, chemosis, painful ophthalmoplegia (III, IV, V1/V2, VI)
Epidemiology
- ~1.3-1.6 per 100,000/yr (higher than historically assumed)
- F>M ~3:1 in adults of reproductive age - driven by COCP, pregnancy, puerperium
- Median age ~37 - far younger than arterial stroke
- ~0.5-1% of all strokes
- Peripartum risk concentrated in the first 6 weeks postpartum
Aetiopathogenesis
An underlying cause is found in ~85%; >1 in ~half. Absence of a cause does not make it idiopathic until the workup is complete.
Prothrombotic - acquired
- COCP (commonest single risk factor in young women), pregnancy and puerperium, HRT
- Malignancy, particularly haematological
- Nephrotic syndrome, inflammatory bowel disease, Behcet
- Antiphospholipid syndrome
- Paroxysmal nocturnal haemoglobinuria - test in unexplained unusual-site thrombosis
- Heparin-induced thrombocytopenia; vaccine-induced immune thrombotic thrombocytopenia (VITT) - anti-PF4 antibodies
- Dehydration, androgens, L-asparaginase, tamoxifen, erythropoietin
Prothrombotic - inherited
- Factor V Leiden, prothrombin G20210A, protein C/S and antithrombin deficiency
Local / mechanical
- Infection - otitis media, mastoiditis, sinusitis, meningitis, facial cellulitis ("danger triangle" -> cavernous sinus)
- Head trauma, neurosurgery, jugular catheter, lumbar puncture
- Dural AV fistula, tumour invasion
Diagnosis
Presentation
- Headache ~90% - the commonest and often the only symptom
- Gradual onset over days, but thunderclap in ~10%; worse lying flat, on Valsalva
- Seizures ~40% - far more than arterial stroke; may be focal or generalised, may be the presentation
- Papilloedema, visual obscurations
- CN VI palsy - false localising sign of raised ICP
- Scalp/periorbital oedema, dilated scalp veins
- Focal deficit, encephalopathy, coma (deep venous system)
Four clinical syndromes
- Isolated intracranial hypertension (headache +/- papilloedema +/- VI palsy) - commonest
- Focal syndrome (deficit +/- seizure)
- Encephalopathy (deep system, bilateral)
- Cavernous sinus syndrome
Imaging
- CT venography or MR venography is the diagnostic test
- Non-contrast CT normal in ~30% - do not use to exclude
- Direct signs: dense triangle / cord sign; empty delta sign on contrast CT
- Indirect: haemorrhagic infarct crossing arterial territories, bilateral parasagittal lesions, diffuse oedema
- MRI: thrombus signal varies with age; SWI/GRE shows thrombosed cortical veins
- Repeat imaging if initial negative and suspicion high - cortical vein thrombosis is easily missed
Bloods
- D-dimer: raised in most, but a normal D-dimer does NOT exclude CVST - particularly with isolated headache or long symptom duration
- FBE, film, coagulation profile, CRP
- Anti-PF4 ELISA if recent adenoviral-vector vaccine or heparin exposure + thrombocytopenia
- Thrombophilia screen (defer to after acute phase and off anticoagulation where interpretation matters), antiphospholipid antibodies
- Pregnancy test
LP
- Only if meningitis suspected, and only after imaging excludes CVST-related mass effect
- Raised opening pressure, raised protein, mild pleocytosis
Management
A. Anticoagulation - the cornerstone
- Full-dose anticoagulation, even in the presence of haemorrhagic venous infarction
- Counter-intuitive but correct: the bleeding is caused by venous congestion, which anticoagulation relieves
- Acute: therapeutic LMWH (preferred over UFH), unless surgery or bleeding risk demands a reversible agent
- Transition to oral:
- Warfarin (INR 2-3) - the best-established option
- DOAC (dabigatran 150 mg BD, rivaroxaban 20 mg daily, apixaban 5 mg BD) - non-inferior in RE-SPECT CVT and ACTION-CVT; reasonable case-by-case, not for antiphospholipid syndrome or pregnancy
Duration
| Setting | Duration |
|---|---|
| Transient/provoked (COCP, pregnancy, infection, trauma) | 3-6 months |
| Unprovoked | 6-12 months |
| Severe thrombophilia, recurrent VTE, active malignancy, APS | Indefinite |
- VITT or HIT - no heparin; use argatroban, bivalirudin, danaparoid or a DOAC, plus IVIg 1 g/kg/day x2; avoid platelet transfusion
B. Raised intracranial pressure
- Serial visual acuity, fields and fundoscopy - visual loss is the preventable disability
- Acetazolamide for persistent intracranial hypertension
- Therapeutic LP if severe papilloedema
- Decompressive craniectomy for impending herniation from large haemorrhagic infarct or oedema - life-saving, and survivors are frequently independent
- Avoid steroids - no benefit, may worsen outcome
C. Seizures
- Treat clinical seizures with an anti-seizure medication (levetiracetam)
- No routine primary prophylaxis - but strongly consider after a first seizure with a supratentorial lesion (high recurrence)
- Continue ~12 months after the acute phase if seizures occurred with a parenchymal lesion
D. Cause-directed
- Antibiotics + surgical drainage for septic CVST (mastoiditis, sinusitis) - prolonged IV course
- Stop COCP permanently and counsel about oestrogen-containing contraception and future pregnancy
- Treat malignancy, PNH, inflammatory disease
E. Endovascular
- Mechanical thrombectomy/local thrombolysis - no benefit in the TO-ACT trial; reserve for deterioration despite adequate anticoagulation
F. Future pregnancy
- Previous CVST is not a contraindication to pregnancy
- Prophylactic LMWH through pregnancy and 6 weeks postpartum
Associations
- Oestrogen exposure - COCP, pregnancy, puerperium, HRT
- Inherited and acquired thrombophilia; antiphospholipid syndrome
- Paroxysmal nocturnal haemoglobinuria
- Behcet disease, inflammatory bowel disease, nephrotic syndrome, sarcoidosis
- Malignancy, particularly haematological; L-asparaginase therapy
- Head and neck infection - mastoiditis, sinusitis, dental
- Heparin-induced thrombocytopenia and vaccine-induced immune thrombotic thrombocytopenia
- Idiopathic intracranial hypertension - overlapping presentation; venous stenosis found in many with IIH
- Dural arteriovenous fistula - may be cause or consequence
Natural history & complications
- Better prognosis than arterial stroke: ~80% functionally independent at follow-up
- Acute mortality ~5-10%; usual mechanism is transtentorial herniation from a large haemorrhagic lesion
- Recanalisation in ~85%, mostly within the first 3-4 months; further recanalisation after 12 months is unusual and repeat imaging beyond then rarely changes management
- Recurrent CVST ~2-4%; other VTE ~4-7%
Poor prognostic markers
- CNS infection
- Underlying malignancy
- Deep venous system thrombosis
- Intracranial haemorrhage on admission imaging
- GCS <9
- Altered mental status
- Age >37
- Male sex
Complications
- Venous infarction and haemorrhage; herniation
- Persistent intracranial hypertension -> optic atrophy and permanent visual loss
- Post-CVST epilepsy
- Chronic headache (very common, often the main residual disability)
- Dural arteriovenous fistula
- Cognitive impairment and fatigue despite "good" mRS - under-recognised; mRS understates true disability here
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