What is the recommended diagnosis and management for transverse and sigmoid sinus thrombosis?

Transverse and Sigmoid Sinus Thrombosis: Diagnosis and Management

Immediate anticoagulation with intravenous unfractionated heparin or subcutaneous low-molecular-weight heparin is the cornerstone of treatment and should be initiated as soon as the diagnosis is confirmed, even in the presence of intracranial hemorrhage caused by the thrombosis itself. 1, 2, 3

Diagnostic Approach

Imaging Strategy

MRI with magnetic resonance venography (MRV) is the preferred initial diagnostic test because it provides superior sensitivity at all stages of thrombosis and visualizes both the venous sinuses and brain parenchyma better than CT. 2, 4

• The optimal MRI protocol combines time-of-flight (TOF) MRV with contrast-enhanced MRV, achieving 92.5% sensitivity and 100% specificity. 4
• Add gradient echo T2 susceptibility-weighted imaging to MRV for the most sensitive sequence combination. 1, 4
• CT with CT venography (CTV) is acceptable in emergency settings when MRI is unavailable, with 95% sensitivity and 91% specificity. 4

Critical Diagnostic Principle

A negative plain CT or MRI does NOT rule out transverse and sigmoid sinus thrombosis—venographic imaging (CTV or MRV) must be performed when clinical suspicion exists. 4

Key Imaging Findings

Direct signs of thrombosis:

• Absence of normal flow void on MRI with altered signal intensity in the transverse/sigmoid sinus 1, 4
• Filling defect within the sinus on contrast-enhanced imaging 4
• "Empty delta" sign showing central hypodensity with surrounding enhancement 1, 4
• Hyperdensity of the sinus on noncontrast CT in acute cases (present in only one-third of cases) 4

Parenchymal changes specific to transverse and sigmoid sinus thrombosis:

• Temporal lobe parenchymal abnormalities (edema, hemorrhage, or infarction) are the characteristic distribution pattern. 1, 4
• Hemorrhagic venous infarction occurs in 40% of cases. 4
• Lesions that cross usual arterial boundaries, particularly with hemorrhagic component, are highly suggestive. 4

Diagnostic Pitfalls to Avoid

Transverse sinus hypoplasia or atresia can mimic thrombosis on TOF MRV. 4

• Asymmetrical sinus drainage is a normal variant that may appear as reduced flow. 4
• Use gradient echo or susceptibility-weighted imaging to distinguish: nonthrombosed hypoplastic sinus will not show abnormal low signal, whereas thrombosed sinus will. 1, 4
• Flow gaps on TOF MRV images are common and can affect interpretation. 2

Reserve catheter angiography for inconclusive CTV/MRV results despite high clinical suspicion or when endovascular treatment is being considered. 1, 4

Clinical Presentation

Headache is the most common presenting symptom, typically diffuse and progressively worsening over days to weeks. 2

• Seizures occur in approximately 40% of patients, significantly higher than arterial stroke. 2
• Presentation timing: 37% acute, 56% subacute, 7% chronic. 2
• Median time from symptom onset to diagnosis is 7 days, reflecting the diagnostic challenge. 2

Management Algorithm

Immediate Treatment

Step 1: Initiate anticoagulation immediately upon diagnosis confirmation 1, 2, 3

• Use either intravenous unfractionated heparin OR subcutaneous low-molecular-weight heparin. 2, 3
• The presence of intracerebral hemorrhage related to the thrombosis is NOT a contraindication to anticoagulation. 1, 3
• Anticoagulation prevents thrombus propagation, increases recanalization, and reduces mortality and severe disability. 2, 3

Step 2: Admit all patients to a stroke unit for close monitoring and specialized care. 3

Duration of Anticoagulation

Tailor duration based on underlying risk factors: 2, 3

• Transient reversible risk factors (e.g., oral contraceptives, pregnancy, postpartum): 3-6 months of oral anticoagulation 2, 3
• Idiopathic thrombosis or mild thrombophilia: 6-12 months 2, 3
• High-risk inherited thrombophilia or recurrent events: Consider indefinite (lifelong) anticoagulation 2, 3

Management of Complications

For elevated intracranial pressure:

• Consider dexamethasone (4-8 mg/day oral or IV) ONLY for patients with significant white matter edema causing mass effect. 2, 3
• Avoid long-term use (>3 weeks) due to significant toxicity. 3

For seizures:

• Treat aggressively with antiepileptic medications. 2, 3

For severe cases with neurological deterioration despite anticoagulation:

• Consider endovascular thrombolysis for patients with absolute contraindications to anticoagulation or failure of initial therapeutic anticoagulation. 1, 2
• Decompressive hemicraniectomy should be considered for severe mass effect, especially in young patients when adequate anticoagulation and intensive care fail to prevent deterioration. 2, 5

Follow-Up Imaging

Perform CTV or MRV at 3-6 months after diagnosis to assess for recanalization in stable patients. 2, 4, 3

Obtain early repeat imaging for patients with persistent or evolving symptoms despite anticoagulation treatment. 2, 4, 3

Etiologic Workup

Evaluate for prothrombotic conditions: 2, 4

• Inherited thrombophilias: protein C/S deficiency, antithrombin III deficiency, factor V Leiden 2, 4
• Female-specific factors: oral contraceptive use, pregnancy, postpartum state 2, 4
• Other factors: malignancy, inflammatory conditions, dehydration, iron deficiency anemia 2, 4, 6

Common Pitfalls

• Delayed diagnosis is common due to variable presentation and slower progression compared to arterial stroke. 2
• CVST may be misdiagnosed as idiopathic intracranial hypertension, especially with isolated headache and papilledema. 2
• Non-contrast CT has limited sensitivity (abnormal in only 30% of cases), so always proceed to venographic imaging when suspicion exists. 2