Cerebral Venous Thrombosis

Diagnosis can be challenging as symptoms may be vague and non-specific, often reflecting raised intracranial pressure (ICP) rather than focal neurology.
Plain CT scans may not readily demonstrate the pathology.

CT venogram is an excellent imaging modality for diagnosis.
MRI/MRV is a good alternative if there is a genuine contraindication to IV contrast.

CVT should be considered in cases of unexplained CNS symptoms (e.g. severe unexplained headache) when the CT scan is unhelpful, particularly if the patient has recognised risk factors.

Females taking oral hormonal contraceptives or those pregnant or in the immediate puerperium appear to be most at risk.

The natural history of CVT is highly variable:

• ~65% of patients have minimal/no symptoms and recover.
• ~20% have a fulminant course with extensive infarction, dependency, or death.

Outcome is highly dependent on the underlying causative pathology.

Treatment is generally with heparin/warfarin, along with treatment of the underlying cause.
In cases of heparin-induced thrombocytopenia (HIT), heparin/LMWH must be withheld and an alternative anticoagulant used.

Management is complex; all suspected or confirmed cases should be referred to a Clinical Haematologist and Neurologist.

History

The first description of the cerebral venous sinuses was made by Roman physician Galen in the 2nd century AD. Galen’s description remained the standard for over 13 centuries, until the work of Andreas Vesalius in the 16th century.

The vein of Galen, also known as the great cerebral vein, is named after Galen.

Epidemiology

• CVT predominantly affects women (~75% of cases).
• ~80% of patients are under 50 years old.
• Numbers are influenced by peripartum and oral contraceptive-associated cases.

Classification

CVT refers to occlusion of venous channels within the cranial cavity and includes:

1. Dural Venous Sinus Thrombosis

• Any dural sinus may be affected, in isolation or in combination.

2. Cortical Vein Thrombosis

• Isolated cortical vein thrombosis without sinus involvement is rare.

3. Deep Cerebral Vein Thrombosis

• These conditions often co-exist.
• Clinical presentation is generally non-specific.

Pathology

Risk Factors

1. Hormonal Factors

• Oral hormonal contraceptives.
• Third trimester and puerperium.

2. Dehydration

3. Hyperviscosity / Procoagulation

• Includes heparin-induced thrombocytopenia (HIT) — requires different treatment.

4. Local Stasis

• Tumour, abscess, aneurysm.

5. Malignancy

6. Infection (Uncommon)

• Middle ear infection (lateral sinus).
• Orbit / midface infection (cavernous sinus).
• Meningitis.
• Severe sepsis.

7. Connective Tissue Diseases

• Note: A substantial number of cases have no obvious precipitating cause.

Complications

1. Raised Intracranial Pressure (ICP)

2. Venous Infarctions

• Occur in ~50% of cases.
• Presentation timing:

Time from symptom onset	Percentage of cases
< 2 days	30%
2–30 days	50%
> 30 days	20%

3. Secondary Haemorrhage

• Haemorrhaging into infarcted regions.

Clinical Features

Presentation

• Symptoms evolve over hours to weeks.
• Less localising than arterial stroke.
• Typically reflects raised ICP.

Features

1. Raised ICP

• Headache (most common).
• Vomiting (especially when protracted and unexplained).
• Confusion.
• Altered conscious state (late).

2. Seizures

3. Cavernous Sinus Thrombosis Features

• Proptosis.
• Chemosis / periorbital oedema.
• Ocular movement paralysis.
• Cranial nerve palsies, particularly if there is extension into the jugular veins.

Prognosis

• Variable: death → neurological deficit → full recovery.

Investigations

Blood Tests

• FBE:
  • Polycythaemia.
  • Low platelets (suggesting TTP or HIT).
  • Leukocytosis (suggesting sepsis).
• CRP.
• ESR.
• U&Es / glucose.
• D-dimer:
  • Elevated → supports diagnosis.
  • Normal D-dimer does not exclude CVT.
• Coagulation profile.
• Procoagulation screen.

CT Scan

• Plain CT is usually the first imaging study.
• Excellent for initial screening of headache.
• May not detect CVT.

Characteristic CT Findings

• High-density delta sign (superior sagittal sinus thrombosis).
• Dense clot sign.
• Cord sign (cord-like hyperattenuation within a dural venous sinus).

CT Venogram

• Most useful modality to confirm CVT.
• IV contrast shows filling defects:
  • Empty delta sign (specific for superior sagittal sinus thrombosis).

MRI / MRV

• Good alternative if IV contrast is contraindicated.
• Best for detecting:
  • Space-occupying lesions.
  • Extent of clot.
  • Venous infarction.

MRI Signal Changes

• Acute clot: isointense on T1, hypointense on T2.
• Subacute clot: hyperintense on T1.
• Cerebral oedema can be identified even without infarction.

Grading of Parenchymal Oedema

Type	MRI Appearance
1	No imaging abnormality
2	High T2
3	High T2 with enhancement
4	Haemorrhage or infarction

Angiography

• Historically the gold standard.
• Now rarely required.
• May be used if CT venogram / MRI equivocal.
• Best for detecting isolated cortical vein thrombosis.

Management

1. Supportive Care

• ABC as required.
• Analgesia for headache.

2. Treat Underlying Cause

• Dehydration.
• Infection.

3. Nursing Position

• 30 degrees head-up to reduce ICP.

4. Seizures

• Treat conventionally.

5. Anticoagulation

• LMWH or IV heparin, followed by warfarin.
• Intracerebral haemorrhage is not a contraindication (as venous-related).
• Duration of anticoagulation should be discussed with haematology.
• Indefinite anticoagulation may be needed in patients with thrombophilia or recurrent CVT.
• In patients with HIT: do not use heparin/LMWH — use an alternative anticoagulant (seek haematology advice).

6. Thrombolysis

• Insufficient evidence to support systemic or local thrombolysis.

7. Neurosurgery

• In cases of severe deterioration, neurosurgical interventions may be life-saving.
• Craniectomy can be used for impending cerebral herniation.

Disposition

• Admission under a Stroke Unit.
• Haematology consultation is essential.

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References

Publications

• Andreae Vesalii. Venarum Arteriarumque, Deceimiquarti Capitis Figura In: de Humani corporis fabrica. 1543
• Alvis-Miranda HR, Milena Castellar-Leones S, Alcala-Cerra G, Rafael Moscote-Salazar L. Cerebral sinus venous thrombosis. J Neurosci Rural Pract. 2013 Oct;4(4):427-38.
• Coutinho JM, de Bruijn SF, deVeber G, Stam J. Anticoagulation for cerebral venous sinus thrombosis. Stroke. 2012 Apr;43(4):e41-e42. 
• Piazza G. Cerebral venous thrombosis. Circulation. 2012 Apr 3;125(13):1704-9.
• Saposnik G, Bushnell C, Coutinho JM, Field TS, Furie KL, Galadanci N, Kam W, Kirkham FC, McNair ND, Singhal AB, Thijs V, Yang VXD; American Heart Association Stroke Council; Council on Cardiopulmonary, Critical Care, Perioperative and Resuscitation; Council on Cardiovascular and Stroke Nursing; and Council on Hypertension. Diagnosis and Management of Cerebral Venous Thrombosis: A Scientific Statement From the American Heart Association. Stroke. 2024 Mar;55(3):e77-e90. 
• Thorell SE, Parry-Jones AR, Punter M, Hurford R, Thachil J. Cerebral venous thrombosis-a primer for the haematologist. Blood Rev. 2015 Jan;29(1):45-50.
• Lam Van Le. Cerebral venous thrombosis. Radiopaedia

FOAMed

• Nickson C. Cerebral Venous Thrombosis. CCC