eMedicine Specialties > Neurology > Neuro-vascular Diseases

Cerebral Venous Thrombosis: Differential Diagnoses & Workup

Author: W Alvin McElveen, MD, Director, Stroke Unit, Lakewood Ranch Medical Center; Neurologist, Manatee Memorial Hospital
Coauthor(s): Ralph F Gonzalez, MD, Private Practice, Bradenton Neurology, Inc; Consulting Staff, Department of Neurology, Blake Hospital, Lakewood Ranch Medical Center, Manatee Memorial Hospital; Andrew P Keegan, MD, Private Practice, Bradenton Neurology, Inc; Consulting Staff, Department of Neurology, Manatee Memorial Hospital, Lakewood Ranch Medical Center, Blake Medical Center
Contributor Information and Disclosures

Updated: Nov 5, 2008

Differential Diagnoses

Other Problems to Be Considered

Abducens (VI) nerve palsy

Workup

Laboratory Studies

• Clinical laboratory studies are useful for determining the possible causes of cerebral venous thrombosis (CVT). Diagnosis of the condition is made on the basis of clinical presentation and imaging studies.
• CBC count is performed to look for polycythemia as an etiologic factor. Decreased platelet count would support thrombotic thrombocytopenic purpura; leukocytosis might be seen in sepsis. In addition, if heparin is used as treatment, platelet counts should be monitored for thrombocytopenia.
• Antiphospholipid and anticardiolipin antibodies should be obtained to evaluate for antiphospholipid syndrome. Other tests that may indicate hypercoagulable states include protein S, protein C, antithrombin III, lupus anticoagulant, and Leiden factor V mutation. These evaluations should not be made while the patient is on anticoagulant therapy.
• Sickle cell preparation or hemoglobin electrophoresis should be obtained in individuals of African decent.
• Erythrocyte sedimentation rate and antinuclear antibody should be performed for screening of systemic lupus erythematosus, Wegener granulomatosis, and temporal arteritis. If elevated, further evaluation including complement levels, anti-DNA antibodies, and neutrophil cytoplasmic antibodies (ANCA) could be considered.
• Urine protein should be checked and, if elevated, nephrotic syndrome considered.
• Liver function studies should be performed to rule out cirrhosis.
• D-dimer values may be beneficial in screening patients who present in the emergency department for headache evaluation.
  • In a study of 18 patients with CVT, Tardy et al reported that D-dimer levels less than 500 ng/mL had a negative predictive value for ruling out the diagnosis in patients with acute headache.⁸
  • In a prospective study of 54 consecutive patients with headache suggestive of CVT, Lalive found that 12 had CVT and, of those, 10 had D-dimer levels greater than 500 ng/mL.⁹ The 2 patients with confirmed CVT and a D-dimer level less than 500 ng/mL had a history of chronic headache lasting longer than 30 days.
  • Kosinski et al (2004) prospectively studied 343 patients with symptoms suggesting cerebral sinus thrombosis.¹⁰ The diagnosis was confirmed in 35, with 34 of these patients showing elevated D-dimer levels greater than 500 mcg/L. Of the 308 patients not having CVT, 27 had positive values. Sensitivity was 97.1%, with a negative predictive value of 99.6%. Specificity was 91.2%, with a positive predictive value of 55.7%. D-dimers were positively correlated with the extent of thrombosis and negatively correlated with duration of symptoms. This test does not establish the diagnosis of CVT, and more definitive studies, such as MR venography (MRV), are necessary. Likewise, if a high suspicion for CVT exists, the test does not definitely exclude the diagnosis but makes the presence of CVT very unlikely.

Imaging Studies

• MRI
  • MRI shows the pattern of an infarct that does not follow the distribution of an expected arterial occlusion. It may show absence of flow void in the normal venous channels.
  • MRV is an excellent method of visualizing the dural venous sinuses and larger cerebral veins.
  • Single-slice phase-contrast angiography (SSPCA) takes less than 30 seconds and provides rapid and reliable information. Many neurologists now consider it to be the procedure of choice in diagnosing cerebral venous thrombosis. In a study of 21 patients, Adams demonstrated a specificity and sensitivity of 100% for SSPCA when compared to alternative imaging techniques.¹¹
  • However, Ayanzen described transverse sinus flow gaps in 31% of patients with normal MRI findings; 90% of these were in the nondominant transverse sinus, and 10% in the codominant sinuses. None was seen in the dominant sinus.¹² These should not be mistaken for thrombosis.
  • Mas et al describe increased intraluminal signal on all planes and with all pulse sequences in patients with lateral sinus thrombosis compared with frank asymmetry in size of the lateral sinus without any abnormal signal in the course of the sinus.¹³
• CT
  • CT is an important imaging technique, as it is often the first imaging study obtained. It may show evidence of infarction that does not correspond to an arterial distribution. However, in the absence of a hemorrhagic component, demonstration of the infarct may be delayed up to 48-72 hours. It is also useful in ruling out other conditions such as neoplasm and in evaluating coexistent lesions such as subdural empyema. CT of the sinuses is useful in evaluating sinusitis; CT of the mastoids may be helpful in lateral sinus thrombosis.
  • Empty delta sign appears on contrast scans as enhancement of the collateral veins in the superior sagittal sinus (SSS) walls surrounding a nonenhanced thrombus in the sinus. However, the sign is frequently absent. Early division of the SSS can give a false delta sign. The dense triangle sign formed by fresh coagulated blood in the SSS and the cord sign representing thrombosed cortical vein are extremely rare.
  • CT angiography has also been used to visualize the cerebral venous system. Ozsvath et al compared CT and MR projection in the identification of cerebral veins and thrombosis.¹⁴ CT venography was superior to MR in identification of cerebral veins and dural sinuses. CT was equivalent to MR in identification of dural sinus thrombosis and therefore is a viable alternative to MR venography in the examination of patients with suspected dural sinus thrombosis. The maximum-intensity-projection technique used, however, did not allow direct visualization of the thrombus by either CT or MR technique.
• Contrast studies
  • Carotid arteriography with delayed filming technique to visualize the venous system was the procedure of choice in the diagnosis of venous thrombosis prior to the advent of MRV. It is an invasive procedure and is therefore associated with a small risk.
  • If MR studies are not diagnostic, conventional angiography should be considered.
  • Direct venography can be performed by passing a catheter from the jugular vein into the transverse sinus with injection outlining the venous sinuses.

Other Tests

EEG may be normal, show mild generalized slowing, or show focal abnormalities if a unilateral infarct occurs. It is helpful in evaluating a seizure focus.

Procedures

Lumbar puncture is helpful in evaluating for meningitis as an associated infectious process. A large unilateral hemispheric lesion or posterior fossa lesion demonstrated on CT scan or MRI is a contraindication to the procedure. In the past, compression of the jugular vein unilaterally with pressure measurement has been utilized. Pressure may be elevated if thrombosis of the contralateral transverse sinus is present. However, collateral circulation or incomplete compression of the jugular vein may yield a false-negative result. Elevation of the intracranial venous pressure is a concern, as it may precipitate herniation. As the maneuver adds little to the diagnosis, it usually is not performed.

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