Cerebral venous sinus thrombosis

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

CVST blocks venous drainage, raising venous and capillary pressure. This causes vasogenic oedema, reduced absorption of cerebrospinal fluid, venous infarction and sometimes intraparenchymal or subarachnoid bleeding. Unlike a typical arterial stroke, symptoms may evolve over days, involve both hemispheres or combine headache, papilloedema and seizures. The superior sagittal, transverse, sigmoid, straight and cortical veins produce different patterns, and multiple segments are often involved.

The history should include pregnancy stage or days postpartum, contraception and hormone therapy, cancer, inflammatory bowel or systemic inflammatory disease, recent infection of ear, sinus, face or mastoid, dehydration, anaemia, thrombocytosis, nephrotic syndrome, previous VTE and family history. Examination includes consciousness, focal neurology, visual fields, fundi, eye movements and signs of sepsis. A convincing risk constellation justifies venous imaging even when arterial stroke screening and unenhanced CT are normal.

Anticoagulation prevents thrombus propagation and supports recanalisation. Haemorrhage caused by venous congestion is part of the disease and is not usually a reason to withhold therapeutic heparin, unlike an unrelated active bleed. Management also addresses seizures, vision-threatening intracranial pressure, infection and mass effect. Later work includes deciding whether the event was provoked, whether thrombophilia testing will change management, contraception or pregnancy counselling and the safe duration and agent for secondary prevention.

Key points

Cerebral venous thrombosis is an uncommon but treatable cause of headache, intracranial hypertension, seizure, focal deficit, encephalopathy or haemorrhagic venous infarction.
Risk is increased by pregnancy and the puerperium, oestrogen-containing contraception, malignancy, inflammatory disease, infection, dehydration, inherited thrombophilia and previous venous thromboembolism.
Headache may be progressive, thunderclap or the only symptom; papilloedema, diplopia from sixth-nerve palsy, focal seizure or a deficit crossing conventional arterial territories should raise suspicion.
A normal non-contrast CT and a low clinical impression do not exclude CVST; obtain CT venography or MR venography when the phenotype or risk factors warrant it.
D-dimer may support assessment in some contexts but cannot safely rule out CVST, particularly with isolated headache, limited clot burden or prolonged symptoms.
Treat acute CVST with therapeutic heparin, usually low-molecular-weight heparin, even when the thrombosis has produced a haemorrhagic venous infarct, unless an independent contraindication exists.
Escalate deterioration despite anticoagulation, impending herniation or severe mass effect to neurocritical, neuroradiology and neurosurgical teams for endovascular or decompressive rescue consideration.
Search proportionately for provoking factors, plan pregnancy-safe treatment where relevant and individualise anticoagulant choice and duration after the acute phase with stroke or haematology input.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Hormonal and pregnancy-related risk

Pregnancy, the puerperium and oestrogen-containing contraception increase venous thrombosis risk, particularly when dehydration or inherited susceptibility also exists.

Systemic prothrombotic states

Malignancy, inflammatory disease, antiphospholipid syndrome, inherited thrombophilia and previous venous thromboembolism can promote cerebral venous clotting.

Infection and local inflammation

Ear, mastoid, sinus or facial infection may extend to adjacent venous sinuses, while systemic infection can increase coagulation and endothelial injury.

Transient physiological contributors

Dehydration, severe anaemia, surgery and selected medicines can compound venous stasis or hypercoagulability and should be interpreted within the complete presentation.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Venous outflow obstruction
Thrombus blocks a cortical vein or dural sinus, raising upstream venous pressure and reducing effective drainage from brain tissue.
2
Oedema and venous infarction
Congestion lowers capillary perfusion and disrupts the blood–brain barrier, causing vasogenic and cytotoxic oedema that can cross arterial boundaries.
3
Haemorrhagic conversion
High venous and capillary pressure ruptures small vessels, producing petechial or confluent haemorrhage within congested tissue.
4
Impaired cerebrospinal-fluid absorption
Sinus obstruction reduces arachnoid-granulation drainage, raising intracranial pressure and causing headache, papilloedema or sixth-nerve palsy through impaired cerebrospinal-fluid resorption.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Intracranial hypertension pattern

Progressive diffuse headache, transient visual obscurations, pulsatile tinnitus, papilloedema and sixth-nerve palsy arise when venous outflow obstruction raises intracranial pressure.

Haemorrhagic venous infarct

Atypical cortical or parasagittal haemorrhage with surrounding oedema, crossing an arterial territory or occurring bilaterally, should prompt immediate venous imaging.

Seizure-predominant presentation

New focal or generalised seizure, especially in pregnancy, postpartum or with headache and deficit, is commoner in CVST than in many arterial strokes.

Deep venous thrombosis

Straight-sinus or internal cerebral vein thrombosis can cause bilateral thalamic oedema, behavioural change, reduced consciousness and eye-movement abnormalities.

Septic CVST

Fever, ear or sinus infection, orbital signs or mastoid tenderness with headache and neurological features raises contiguous infection and requires urgent antimicrobial and source-control assessment.

Postpartum warning

A persistent or atypical postpartum headache, seizure, papilloedema or focal deficit must not be attributed automatically to migraine, pre-eclampsia or dural puncture.

Red flags requiring action

Declining consciousness, new pupillary abnormality or extensor posturing indicates mass effect or herniation and needs immediate neurocritical and neurosurgical action.
Rapidly worsening vision or severe papilloedema requires urgent ophthalmic and neurological pressure management to prevent permanent visual loss.
Fever with orbital, sinus, ear or mastoid infection suggests septic thrombosis requiring immediate intravenous antibiotics and ENT or surgical source control.
Pregnancy or postpartum seizure with headache and hypertension requires simultaneous assessment for CVST, eclampsia, arterial stroke and posterior reversible encephalopathy.
New deficit or seizure despite established anticoagulation may indicate thrombus propagation, worsening oedema or haemorrhage and warrants urgent repeat imaging.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
CT venographyFirst step
Why
Demonstrate absent filling or thrombus in dural sinuses and cortical veins rapidly alongside emergency CT.
Interpretation and limitations
Review source images for anatomical variants, arachnoid granulations and timing artefact; an empty-delta sign is not required for diagnosis.
02
MRI brain with MR venography
Why
Define thrombus age, venous infarction, oedema and deep or cortical vein involvement without ionising radiation.
Interpretation and limitations
Flow-related artefact can mimic occlusion and signal changes evolve with clot age; specialist neuroradiology correlation is important.
03
Non-contrast CT brain
Why
Identify haemorrhage, oedema, venous infarction or another cause before dedicated venous imaging.
Interpretation and limitations
CT may be normal; hyperdense sinus or a non-arterial haemorrhagic lesion raises suspicion but cannot replace venography.
04
Full blood count, coagulation and renal profile
Why
Detect anaemia, thrombocytosis, thrombocytopenia, infection and renal or coagulation constraints before anticoagulation.
Interpretation and limitations
Correct important abnormalities and calculate treatment dosing appropriately; routine coagulation tests do not assess every thrombophilia or DOAC effect.
05
Pregnancy and provoking-factor assessment
Why
Identify pregnancy, puerperium, hormone exposure, malignancy, inflammatory disease or infection that changes immediate and long-term care.
Interpretation and limitations
Use history, examination and targeted testing; necessary venous imaging and anticoagulation should not be withheld during pregnancy when clinically indicated.
06
Thrombophilia testing
Why
Identify selected acquired or inherited conditions when the result will alter duration, drug choice or family or pregnancy counselling.
Interpretation and limitations
Test selectively with haematology because acute thrombosis, pregnancy and anticoagulants can invalidate results; indiscriminate inpatient panels create false diagnoses.
07
Ophthalmic pressure assessment
Why
Document papilloedema and visual function when intracranial hypertension is suspected.
Interpretation and limitations
Record acuity, fields and optic-disc findings; visual decline can occur despite improving headache and needs urgent specialist treatment.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Migraine or primary headache

A familiar recurrent phenotype with normal examination supports migraine, but new progressive or thunderclap pain with thrombosis risk, seizure or papilloedema requires venous imaging.

Idiopathic intracranial hypertension

Both cause headache and papilloedema; normal venography and absence of a secondary cause are required before raised pressure is called idiopathic.

Arterial stroke

A sudden deficit in a conventional arterial territory supports arterial occlusion, while seizure, headache and haemorrhagic lesions crossing arterial boundaries favour venous disease.

Meningitis or subarachnoid haemorrhage

Fever and meningism suggest infection, while abrupt maximal headache and basal subarachnoid blood suggest aneurysmal haemorrhage; cerebrospinal-fluid testing follows imaging and safety assessment.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01SUSPECTHeadache with CVST cluesFirst stepHeadache is new or progressive with papilloedema, seizure, focal signs or a prothrombotic context.

1Assess consciousness, pupils, focal neurology, fundi, pregnancy or postpartum status, infection and VTE risk while treating seizures or instability.
2Obtain urgent CT brain plus CT venography, or MRI with MRV when clinically and logistically appropriate; do not stop at a normal unenhanced CT.
3Discuss promptly with stroke or neurology and neuroradiology if imaging is equivocal or cortical-vein thrombosis remains plausible.
4AlternativeBegin therapeutic anticoagulation once diagnosed unless an independent contraindication requires an alternative specialist plan.

02ANTICOAGConfirmed acute CVSTVenous imaging demonstrates cerebral sinus or cortical venous thrombosis.

1Select therapeutic low-molecular-weight or unfractionated heparin according to renal function, pregnancy, procedure need and local protocol.
2Continue treatment despite a haemorrhagic venous infarct unless another active bleeding contraindication is present, documenting the mechanism and specialist decision.
3Treat seizure, infection, intracranial hypertension, dehydration and provoking factors and monitor neurological and visual change closely.
4After stabilisation, transition to an appropriate longer-term anticoagulant and duration based on provocation, recurrence risk, pregnancy and current specialist guidance.

03PRESSUREVision-threatening intracranial hypertensionPapilloedema, sixth-nerve palsy or declining visual fields indicates pressure-related optic-nerve risk.

1Obtain urgent formal acuity, field and optic-disc assessment and repeat venous and brain imaging if symptoms are worsening.
2Maintain therapeutic anticoagulation and use specialist-selected pressure-lowering treatment while avoiding dehydration that may worsen thrombosis.
3Discuss cerebrospinal-fluid diversion, optic-nerve sheath fenestration or venous intervention when vision deteriorates despite medical care.
4Monitor visual function rather than headache alone because papilloedema can progress after pain improves.

04RESCUEClinical deterioration despite treatmentConsciousness or deficit worsens despite adequate anticoagulation and physiological care.

1Repeat ABC, glucose and neurological assessment and obtain urgent CT or MRI to define propagation, haemorrhage, oedema and herniation.
2Confirm correct anticoagulant dosing and assess thrombocytopenia, renal change, infection and recurrent seizure.
3EscalationEscalate to a neurovascular centre for case-by-case endovascular thrombectomy or thrombolysis consideration when deterioration continues.
4Seek decompressive neurosurgery urgently for malignant mass effect or impending herniation, independent of the endovascular decision.

Key medicines and prescribing safety4 treatments · regimens, roles and cautions

Prevents propagation and supports recanalisation during the acute phase of confirmed cerebral venous thrombosis.

Enoxaparin

Use a therapeutic weight-based subcutaneous regimen, commonly 1 mg/kg every 12 hours, adjusted for renal function, body weight, pregnancy and the local anticoagulation protocol.

Check platelets, renal function, weight, active bleeding and procedure plans; haemorrhagic venous infarction alone is not usually a contraindication, but unrelated bleeding may be.

Provides adjustable therapeutic anticoagulation in unstable or procedurally complex CVST under close specialist monitoring.

Unfractionated heparin

Give an intravenous loading and infusion regimen titrated by the hospital heparin protocol when rapid reversibility, severe renal impairment or an urgent procedure makes it preferable.

Monitor the specified coagulation assay and platelets, avoid subtherapeutic interruptions and consider heparin-induced thrombocytopenia when counts fall.

Terminates acute seizures and reduces recurrence when a haemorrhagic cortical venous lesion or repeated events create substantial risk.

Antiseizure treatment

Treat clinical seizures using the local emergency seizure protocol, then choose maintenance agent and dose with neurology according to recurrence, lesion and pregnancy context.

Do not give long-term prophylaxis automatically to every patient; account for sedation, interactions with anticoagulants, teratogenicity and renal or hepatic function.

Treats the infectious driver of septic venous thrombosis alongside anticoagulation and surgical source control decisions.

Antibiotic therapy for septic CVST

Start prompt intravenous broad-spectrum treatment covering the suspected ear, sinus, orbital or systemic source, then narrow to cultures and current local microbiology guidance.

Do not delay for culture results in sepsis; adjust for allergy and renal function and involve microbiology, ENT, ophthalmology or neurosurgery as anatomy requires.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Seizures and status epilepticus

Cortical venous congestion and haemorrhage are strongly epileptogenic, causing focal or bilateral convulsions and occasionally persistent electrographic seizures.

Haemorrhagic venous infarction

Congested tissue can infarct and bleed, producing mass effect and focal disability despite the haemorrhage arising from a thrombotic disorder.

Raised pressure and herniation

Diffuse venous congestion or a large swollen infarct can reduce consciousness and cause herniation, requiring neurocritical, endovascular or decompressive rescue consideration.

Visual loss and recurrence

Sustained papilloedema damages optic nerves, while an unidentified or persistent prothrombotic state leaves ongoing risk of cerebral or systemic venous thrombosis.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Repeat neurological observations and escalate new seizure, focal deficit, vomiting or reduced consciousness immediately.
Track visual acuity, fields, diplopia and papilloedema when intracranial pressure is raised, using formal ophthalmic measurements for trend.
Monitor anticoagulant dose, renal function, platelets, haemoglobin, bleeding and planned procedures throughout acute and longer-term treatment.
Review pregnancy status, breastfeeding, contraception and future pregnancy plans before selecting a longer-term anticoagulant or antiseizure medicine.
Confirm resolution of infection and completion of ear, sinus, dental or other source control in septic cases.
Arrange follow-up imaging only when it will answer a clinical question under the specialist plan; symptom recovery and recurrence risk are not determined by recanalisation alone.
Revisit treatment duration and thrombophilia results after the acute phase, when transient assay interference and provoking factors can be interpreted correctly.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Haemorrhage can require heparin

Bleeding from venous back-pressure is mechanistically different from a primary arterial rupture, so therapeutic anticoagulation usually remains the treatment.

Headache-only disease exists

Absence of focal deficit or seizure does not exclude CVST when new persistent headache and a strong prothrombotic context are present.

D-dimer has blind spots

Limited clot burden, isolated headache and longer symptom duration can produce a negative result, making it unsuitable as a universal rule-out test.

Deep veins affect both thalami

Bilateral thalamic oedema is an important clue to straight-sinus or internal cerebral vein thrombosis and may resemble metabolic encephalopathy.

Pregnancy changes drugs, not urgency

Maternal neurological imaging and therapeutic LMWH are compatible with urgent care when clinically indicated; delay can harm both patient and fetus.

Testing timing matters

Protein C, protein S, antithrombin and lupus anticoagulant results can be altered by thrombosis, pregnancy or anticoagulation and require expert scheduling.

11Common pitfallsFrequent interpretation and management errors.

01
Do not stop investigation at a normal non-contrast CT when headache, papilloedema, seizure or risk factors support CVST.
02
Do not use a negative D-dimer as a universal exclusion test for isolated or subacute CVST presentations.
03
Do not withhold anticoagulation solely because imaging shows haemorrhagic venous infarction.
04
Do not perform lumbar puncture for pressure symptoms before imaging has excluded mass effect or another contraindication.
05
Do not order a broad thrombophilia panel during acute thrombosis without deciding how timing and results will alter care.
06
Do not choose warfarin, a DOAC or an antiseizure medicine in pregnancy without obstetric, haematology and neurology input.
07
Do not follow headache alone when papilloedema threatens vision or consciousness is deteriorating.