What is cortical venous sinus thrombosis?

Cerebral Venous Sinus Thrombosis (CVST)

Cerebral venous sinus thrombosis (CVST) is a rare but potentially life-threatening condition characterized by blood clot formation within the dural venous sinuses, cerebral veins, or cortical veins, which disrupts normal blood drainage from the brain and can lead to venous hypertension, venous infarcts, hemorrhage, and seizures. 1, 2

Clinical Presentation

CVST typically presents with the following symptoms:

• Headache - Most common symptom (present in ~90% of patients), typically diffuse and progressively worsening over days to weeks 1
• Focal neurological deficits - Hemiparesis, aphasia, and other cortical signs 1
• Seizures - Occur in approximately 40% of patients 1
• Altered mental status - Particularly with deep venous system involvement 1, 3
• Papilledema - Due to increased intracranial pressure 1
• Visual disturbances - Including diplopia from sixth nerve palsy 1

The clinical manifestations vary depending on the location of thrombosis:

• Superior sagittal sinus (most common location): Headache, increased intracranial pressure, papilledema, motor deficits, seizures 1
• Lateral sinus: Headache, ear pain, constitutional symptoms (if associated with infection) 1
• Deep cerebral venous system (16% of cases): Rapid neurological deterioration, altered consciousness, bilateral thalamic involvement 1

Diagnostic Approach

Imaging

• MRI with MR venography (MRV) - First-line imaging modality with highest sensitivity for detecting both thrombus and parenchymal changes 3
• CT with CT venography (CTV) - Reasonable alternative when MRI is contraindicated or unavailable (87% accuracy) 3
• Key imaging findings: Absence of flow void in the sinus, T2 hypointensity suggesting thrombus, "empty delta" sign 3

Laboratory Tests

• D-dimer - May help exclude CVST when negative, but has poor specificity 1
• Recommended blood studies:
  • Complete blood count
  • Chemistry panel
  • Prothrombin time
  • Activated partial thromboplastin time 1
• Screening for prothrombotic conditions - Especially important in the initial assessment 1

Lumbar Puncture

• Not routinely recommended unless meningitis is suspected 1
• Elevated opening pressure is common (>80% of patients) 1

Risk Factors

Common risk factors include:

• Oral contraceptives
• Pregnancy/puerperium
• Thrombophilia
• Recent infections
• Dehydration
• Malignancy
• Systemic diseases 1, 4

In approximately 30% of cases, no underlying etiology can be identified 4.

Treatment Approach

Anticoagulation

• First-line therapy: Initiate anticoagulation with either intravenous unfractionated heparin or subcutaneous low molecular weight heparin 3
• Anticoagulation is recommended even in the presence of hemorrhagic changes 3
• Non-heparin based anticoagulants should be considered if there is concern for heparin-induced thrombocytopenia 3

Endovascular Therapy

• Consider in severe cases or patients who fail to improve on anticoagulation 3
• Options include:
  • Local thrombolysis
  • Mechanical thrombectomy (devices such as the Penumbra System have shown effectiveness) 5, 6
  • Combined approaches 3

Surgical Management

• Decompressive hemicraniectomy may be considered for patients with parenchymal lesions leading to herniation 3

Duration of Anticoagulation

• 3 months for transient risk factors
• 6-12 months for idiopathic thrombosis or mild thrombophilia
• Lifelong for high-risk thrombophilia, recurrent events, or antiphospholipid syndrome 3

Follow-up and Monitoring

• Early follow-up imaging (CTV or MRV) for patients with persistent or evolving symptoms 3
• Follow-up imaging at 3-6 months to assess recanalization in stable patients 3
• Close neurological monitoring during the acute phase 3

Common Pitfalls and Caveats

1. Delayed diagnosis - Median delay from symptom onset to diagnosis is 7 days; maintain high clinical suspicion 1
2. Misdiagnosis - CVST may be confused with other conditions due to its variable presentation 1
3. Isolated headache - Occurs in up to 25% of patients without focal neurological findings, presenting a diagnostic challenge 1
4. Normal initial CT - Non-contrast CT is often normal in early CVST (abnormal findings in only ~30% of cases) 3
5. Bilateral brain involvement - Unlike arterial strokes, CVST can cause bilateral symptoms 1