CT Case 071

The contrast enhanced CT demonstrates non-enhancement of the right transverse dural venous sinus, and of the superior sagittal dural venous sinus.

These findings indicate dural venous sinus thrombosis in these locations.

On the non-contrast scan, we again see the thrombus in the right transverse dural venous sinus.

However, while typically an acute thrombus is hyperdense, in this case it is hypodense, this suggests subacute presentation.

Towards the vertex, there is a non-enhancing hyperdense cortical vein. The hyperdensity seen here, suggests it is an acute cortical vein thrombus.

There is no evidence of associated parenchymal oedema or haemorrhage, which can occur secondary to venous hypertension.

Cerebral venous thrombosis (CVT) is the umbrella term to describe the occlusion of venous channels in the cranial cavity. This can be broken down into the diagnoses of;

• Dural venous thrombosis (any sinus can be affected; superior sagittal sinus, cavernous sinus, straight sinus, transverse sinus, sigmoid sinus)
• Cortical vein thrombosis
• Deep cerebral vein thrombosis

Each of these often co-exist and clinical presentation may be indistinguishable.

Predisposing factors to CVT include;

• Hormonal (exogenous, pregnancy)
• Steroids
• Prothrombotic haematological conditions: e.g. factor II mutation, sickle cell disease, factor V Leiden)
• Local factors (e.g. skull abnormalities/trauma, compressing mass, infection
• Systemic illness (dehydration, sepsis, malignancy)

Patients can present with a range of symptoms. Almost all will have headache, other features include altered vision, nausea, vomiting, reduced conscious state, there may be focal neurological deficits and seizures

Imaging modalities

Non-contrast CT brain

While CT venogram is required to make the diagnosis of cerebral venous sinus thrombosis, a non-contrast CT scan may show some features to suggest the diagnosis.

Signs on non-contrast CT that should raise concern for CVST are;

Hyperdensity of the vein or sinus involved

Infarction +/- haemorrhage – caused by venous congestion. This will be in the distribution of venous drainage, rather than in an arterial distribution and will often be in close proximity to a venous sinus.

CT Venogram

A CT venogram has 95% sensitivity for identifying a filling defect due to thrombus.

One classifical radiological finding is the ‘Empty Delta Sign’. It is the the CT sign of thrombosis of the superior sagital sinus, contrast outlines a triangular filling defect which represents thrombus.  Of note, it may not be seen in the acute phase.

The mainstay of treatment is anticoagulation to prevent progression to venous infarction.

Anticoagulation is administered even in the setting of haemorrhagic venous infarction.

The prognosis of CVST is highly variable, with some patients having minimal or no symptoms and an uneventful recovery, while others suffer extensive venous infarction resulting in significant brain injury or death.

This patient was started on therapeutic clexane and received haematology review during her admission. A full thrombophilia screen was performed with most results currently pending. She was discharged on apixaban. She will also need an outpatient CT chest abdomen pelvis to investigate for potential occult malignancy.

• Sagittal section showing the dural venous sinuses and the great cerebral vein. Teach Me Anatomy.
• Ulivi L, Squitieri M, Cohen H, Cowley P, Werring DJ. Cerebral venous thrombosis: a practical guide. Pract Neurol. 2020 Oct;20(5):356-367.
• Neuroimaging Cases 002 • LITFL • CMC Radiology
• Nickson C. Cerebral Venous Thrombosis. LITFL