Is measurement of D-dimer useful in the diagnosis of cerebral venous thrombosis?

Background: The diagnosis of cerebral venous thrombosis (CVT) is a challenge because its clinical presentation is variable, brain CT may be normal, and MRI is not always available. Furthermore, early treatment may be effective. As D-dimer ( DD) measurement is a sensitive test for the exclusion of venous thromboembolism, the authors studied whether this test could be useful in the diagnosis of CVT. Methods: A prospective study of 54 consecutive patients with headaches suggestive of CVT was conducted between October 2000 and September 2002. DD levels were tested for all patients in the emergency room before brain CT or MRI was performed. Results: Twelve ( 22%) of the 54 patients had CVT, and 10 (83%) of these 12 patients had DD level of > 500 ng/mL ( sensitivity of 83% and negative predictive value of 95%). Two patients with confirmed CVT and DD of < 500 ng/mL had a history of chronic headache of > 30 days' duration. In the 42 patients without confirmed CVT, only 4 patients had DD level of < 500 ng/mL ( specificity of 90% and positive predictive value of 71%). Conclusions: DD test is useful in the diagnosis of acute CVT. A value below 500 ng/mL makes acute thrombosis unlikely.