Cerebral Venous Sinus Thrombosis (CVST)
Cerebral venous sinus thrombosis (CVST) is a rare form of stroke (0.5-1% of all strokes) caused by blood clot formation in the brain's venous sinuses or cerebral veins, leading to impaired venous drainage and increased intracranial pressure. 1, 2
Clinical Presentation
- Headache is the most common symptom, occurring in nearly 90% of patients, typically diffuse and progressively worsening over days to weeks 1
- Seizures occur in approximately 40% of patients, which is significantly higher than in arterial stroke 1, 2
- Focal neurological deficits, most commonly hemiparesis and aphasia, are present in many CVST patients 1
- Papilledema and diplopia (sixth nerve palsy) due to increased intracranial pressure are common manifestations 1
- Altered mental status, especially with deep venous system involvement, can occur without obvious focal neurological abnormalities 3, 2
- Presentation is typically subacute with slower symptom progression (37% presenting acutely, 56% subacutely, and 7% chronically) 2
Patient Demographics and Risk Factors
- CVST predominantly affects younger individuals, with 78% of cases occurring in patients under 50 years of age 2
- Women are more frequently affected than men, particularly those taking oral contraceptives or who are pregnant/postpartum 2
- Major risk factors include: 2
- Prothrombotic conditions (inherited thrombophilias such as protein C deficiency, protein S deficiency, antithrombin III deficiency, factor V Leiden)
- Oral contraceptive use
- Pregnancy and puerperium
- Malignancy
- Inflammatory conditions
- Dehydration 1
Diagnostic Approach
Laboratory Studies
- D-dimer may be elevated but a normal level doesn't exclude CVST, especially with limited clot burden 1
- Routine blood studies (CBC, chemistry, PT, aPTT) should be performed 1
Imaging
- Non-contrast CT has limited sensitivity (abnormal in only 30% of cases) 3, 2
- MRI with MR venography is more sensitive and is the preferred diagnostic modality 3, 1, 2
Comparison of CT vs MRI for CVST Diagnosis
| CT+CTV | MRI+MRV |
|---|---|
| Good visualization of major venous sinuses | Better visualization of superficial and deep venous systems |
| Quick (5-10 min) and readily available | Better definition of brain parenchyma |
| Fewer motion artifacts | Early detection of ischemic changes |
| Can be used in patients with pacemakers or claustrophobia | No radiation exposure |
| Limited in detecting cortical and deep venous thrombosis | Better detection of cortical and deep venous thrombosis [3] |
Common Diagnostic Pitfalls
- Delayed diagnosis is common due to variable presentation and slower progression (median 7 days from symptom onset to diagnosis) 2
- May be misdiagnosed as idiopathic intracranial hypertension, especially when presenting with isolated headache and papilledema 2
- Normal non-contrast CT does not exclude CVST; further imaging with CTV or MRV should be pursued when clinical suspicion is high 2
- Isolated mental status changes without focal neurological deficits (more common in elderly and with deep venous system involvement) can lead to missed diagnosis 3
- CVST can mimic arterial stroke but typically has more subacute presentation and may cross arterial boundaries 2
Treatment
- Anticoagulation is the mainstay of treatment, even in the presence of hemorrhagic lesions 2
- Intravenous heparin or subcutaneous low molecular weight heparin is recommended initially 3
- For patients with severe mass effect or intracranial hemorrhage with neurological deterioration: 3
- Endovascular therapy may be considered
- Decompressive hemicraniectomy may be life-saving in severe cases