From the Guidelines
D-dimer testing should not be relied upon as a primary diagnostic tool for cerebral venous sinus thrombosis (CVST), but a normal D-dimer level may help identify patients with low probability of CVT, according to a sensitive immunoassay or rapid enzyme-linked immunosorbent assay (ELISA) 1. When considering the role of D-dimer in CVST, it's essential to recognize its limitations. The sensitivity of D-dimer for CVST ranges from 80-90%, but its specificity is poor due to potential elevations in various conditions such as infection, inflammation, pregnancy, and malignancy.
- A normal D-dimer level can help exclude CVST in patients with low clinical probability, but it should not preclude further evaluation if there is a strong clinical suspicion of CVT 1.
- Elevated D-dimer levels are not specific enough to confirm the diagnosis of CVST, necessitating further investigation with imaging studies. The preferred diagnostic approach for suspected CVST involves neuroimaging, specifically MRI with MR venography or CT venography, which can directly visualize the cerebral venous system and definitively diagnose or exclude CVST.
- Clinical assessment remains crucial, as CVST presents with variable symptoms including headache, seizures, focal neurological deficits, and altered mental status.
- D-dimer should be considered an adjunctive test rather than a primary diagnostic tool for CVST, particularly in patients with low clinical probability, as suggested by the American Heart Association/American Stroke Association 1.
From the Research
Role of D-Dimer in CVST
- D-dimer levels are significantly elevated in patients with cerebral venous sinus thrombosis (CVST) compared to controls 2, 3, 4
- The sensitivity and specificity of predicting CVST using only D-dimer are 94.1% and 97.5%, respectively 2
- D-dimer in combination with fibrinogen may increase the predictive value of acute CVST 2
- D-dimer is useful in patients suspected of CVST and patients with positive test results should be urgently sent for MR imaging 3
- Higher D-dimer levels are associated with complications of the disease and fatal course 4
Diagnostic Criteria
- MRI with magnetic resonance venogram (MRV) is considered the gold standard for diagnosis of CVST 5, 6
- D-dimer concentration may be an indicator of CVST, and the need for neuroimaging tests correlated with clinical factors 4
- Low levels of D-dimer cannot be taken to exclude CVST 4
Clinical Implications
- D-dimer may serve as an important screening tool to determine the urgency of obtaining magnetic resonance imaging/magnetic resonance venography or digital subtraction angiography in patients presenting with clinical symptoms that are suspected of CVST 2
- Timely diagnosis and treatment can reduce morbidity and mortality, remarkably improving the outcome in affected individuals 5