What are the diagnostic criteria for Cerebral Venous Thrombosis (CVT) in a young to middle-aged woman with a history of thrombophilia, pregnancy, or oral contraceptive use, presenting with symptoms such as headache, seizures, and focal neurological deficits?

Diagnostic Criteria for Cerebral Venous Thrombosis

The diagnosis of CVT is established through clinical suspicion based on characteristic symptoms combined with imaging confirmation showing thrombosis in cerebral veins or dural sinuses. 1, 2

Clinical Diagnostic Features

Cardinal Symptoms

• Headache is the most critical diagnostic clue, present in nearly 90% of CVT cases and may be the sole manifestation in up to 25% of patients 1, 2
• The headache typically presents as diffuse and progressive over days to weeks, though thunderclap or migrainous patterns can occur 1
• Isolated headache without focal signs or papilledema represents a significant diagnostic challenge and should prompt consideration of CVT 1

Additional Clinical Manifestations

• Seizures occur in approximately 40% of patients, which is a distinguishing feature from other headache disorders 3
• Focal neurological deficits including hemiparesis, aphasia, sensory symptoms, or other cortical signs when venous infarction or hemorrhage occurs 1, 4
• Signs of increased intracranial pressure: papilledema, diplopia from sixth nerve palsy, vomiting, or impaired consciousness 1, 5, 6

High-Risk Patient Populations Requiring Heightened Suspicion

• Young to middle-aged women using oral contraceptives (relative risk 15.9, dramatically increased with concurrent thrombophilia) 1
• Pregnancy and puerperium patients (CVT accounts for up to 57% of pregnancy-related strokes, highest risk in third trimester) 4, 6
• Patients with known thrombophilia (34% of CVT cases have inherited or acquired prothrombotic conditions) 1

Imaging Confirmation (Required for Diagnosis)

First-Line Imaging

• MRI with MR venography is the most sensitive diagnostic tool and should be the preferred initial imaging modality 3, 7
• MRI with gadolinium is abnormal in all CVT cases, making it superior to CT 5
• CT venography is an acceptable alternative when MRI is unavailable or contraindicated 3, 7

Important Imaging Pitfalls

• Non-contrast CT may be normal in up to 70% of CVT cases, potentially leading to missed diagnosis 3
• Non-contrast CT was abnormal in only 62.5% of confirmed CVT cases in one series 5
• Contrast-enhanced techniques (CT venography or MR venography) are significantly more accurate than non-contrast studies 7

Initial Laboratory Evaluation

Recommended Screening Tests

• Complete blood count, chemistry panel, prothrombin time, and partial thromboplastin time 2
• Screening for prothrombotic conditions: oral contraceptive use, underlying inflammatory disease, infectious processes, inherited thrombophilia 2, 3
• D-dimer testing: A normal D-dimer by sensitive immunoassay may help identify low-probability patients, but should never preclude further evaluation if clinical suspicion is high 2, 3

Lumbar Puncture Considerations

• Elevated opening pressure is present in >80% of CVT patients 2
• No specific cerebrospinal fluid abnormalities exist for CVT 2
• Lumbar puncture is typically not useful unless meningitis is suspected, especially when imaging already confirms diagnosis 2

Diagnostic Algorithm

1. Recognize high-risk clinical scenario: Progressive headache in young woman on oral contraceptives, pregnant/postpartum patient, or patient with thrombophilia 1, 2

2. Identify characteristic symptoms: Headache (especially progressive), seizures, focal deficits, or signs of increased intracranial pressure 1, 2, 3

3. Obtain definitive imaging immediately: MRI with MR venography preferred; CT venography if MRI unavailable 3, 7

4. Perform initial laboratory screening: CBC, coagulation studies, prothrombotic workup 2

5. Consider D-dimer only as adjunct: Normal result does not exclude CVT with high clinical suspicion 2, 3

Critical Diagnostic Pitfalls to Avoid

• Do not rely on non-contrast CT alone - it misses 30-70% of CVT cases 3, 5
• Do not dismiss isolated headache - it may be the only manifestation in 25% of cases 1, 2
• Do not exclude CVT based on normal D-dimer if clinical suspicion remains high 2, 3
• Do not delay imaging in pregnant patients due to radiation concerns - MRI is safe and should be used preferentially 6

Prognostic Imaging Features

• Parenchymal involvement (infarction or hemorrhage) on imaging correlates with worse neurological outcomes and higher risk of sequelae 5, 6
• Superior sagittal and transverse sinuses are most commonly affected 6