Use of Imaging in the Diagnosis and Management of Cerebral Venous Sinus Thrombosis

Introduction

Cerebral venous sinus thrombosis is a rare and disabling disorder that forms 0.5 percent of all strokes. It causes partial or complete occlusion of blood flow in the superficial or deep venous system. The disorder occurs more predominantly in young adults, children, and women. The diagnosis of central venous thrombosis requires high suspicion. In earlier times, central venous sinus thrombosis was identified during post-mortem. The availability of advanced neuroimaging techniques has resulted in better diagnoses.

What Is Cerebral Venous Thrombosis?

Cerebral venous thrombosis occurs when a blood clot forms in the brain’s venous sinuses. It inhibits blood draining from brain tissues resulting in bleeding. The disease can eventually lead to stroke (damage to the brain caused by interruption of blood supply).

What Are the Locations for Venous Sinus Thrombosis?

• Major Dural Sinuses - Include superior sagittal (largest sinus that receives blood from the cerebral hemisphere), transverse (blood drains from the back of the head), straight (area in the skull below the brain that receives blood), and sigmoid sinuses (it drains the blood into an internal jugular vein).

• Cortical veins

• The temporal lobe is drained by a vein of Labbe (superficial cerebral vein).

• The superior sagittal sinus is drained by a vein of Trolard (superficial cerebral vein).

• Deep Vein - It is drained by internal cerebral and thalamostriate veins (the largest tributary of an internal cerebral vein).

• Cavernous sinus (plexus of vein that surrounds internal carotid artery)

What Are the Symptoms of Central Venous Thrombosis?

The symptoms depend on the severity of the clot and its location. The symptom includes

• Headache that keeps getting worse

• Seizures

• Altered mental status and neurologic deficits if a brain bleed is present.

• Blurred vision

• Fainting or loss of consciousness.

• Loss of control over movements in body parts.

• Coma

What Are the Risk Factors for Central Vein Thrombosis Formation?

The risk factor for central vein thrombosis development include

• Thrombophilias (a condition where blood clot forms quickly) can develop or be acquired due to genetics.

• Infections such as intracranial, regional (ear, nose, throat, head, and neck), or systemic can be risk factors for disease development.

• Trauma causing head injury, requiring cranial surgery, lumbar puncture (testing of fluid surrounding brain and spine), or endovascular intervention can cause central vein thrombosis formation.

• Pregnancy or puerperium (6 to 8 weeks after delivery when reproductive organs return to normal).

• Malignancy which is intracranial or extracranial.

• In women, medications like oral contraceptives, steroids, and anti-neoplastic drugs.

• Inflammatory conditions like vasculitis (swelling and redness in blood vessels), systemic lupus erythematosus (immune attacking body tissue in various areas), and inflammatory bowel disease (an intestinal disease that causes swelling and redness).

• Hematological diseases include iron deficiency anemia (lack of blood) and polycythemia (abnormally high red blood cells).

• Hyperthyroidism (excessive thyroid hormone production).

• Dehydration or sepsis (fatal complication caused by infection).

• In neonates, shock and dehydration are common causes of venous thrombosis.

If central venous thrombosis is left untreated, it can cause life-threatening complications.

What Is the Radiologic Evaluation for Central Vein Thrombosis?

Radiological examination plays an important role in diagnosing central venous sinus thrombosis. Neuroimaging must be done immediately to confirm the diagnosis and initiate treatment.

• Angiography

The diagnosis of cerebral venous thrombosis was confirmed by contrast arteriography. The findings in central venous thrombosis include filling defects caused by thrombosis within the venous sinus and occlusion in the draining sinus.

• Computed Tomography

CT is the most common imaging used in acute stroke patients. The imaging can identify subacute ischemia (reduced blood flow) and acute hemorrhage (bleeding inside the body) of parenchyma (functional brain tissue) or subarachnoid (region containing cerebrospinal fluid, blood vessels). Specific parenchymal lesions that appear during imaging are suggestive of central vein thrombosis. It includes bilateral lesions, lesions that cross anterior territories, and juxtacortical lesions (white matter lesions). In a few patients, thrombus in central venous sinuses appears as hyperdense (increase in density) in plain CT. The hyperdensity in CT scans is also known as a dense triangle sign (fresh clot formation in cortical vein or sinus). However, plain CT shows normal imaging in 30 percent of patients.

• CT Venography

The advantage of CT imaging is the flexibility to add CT venography protocol to identify occlusive diseases in prominent cerebral veins and sinuses. It is a simple technique for thrombosis identification. CT venography aids in rapid image-taking and is not contraindicated in patients with pacemakers (a device that controls irregular heart rhythms). It must be ensured that scanning with this technique is made early enough and on time after contrast administration to avoid defects.

• Magnetic Resonance Imaging (MRI) Or Magnetic Resonance Venography

It is a sensitive tool for identifying central venous thrombosis. Diagnostic imaging can identify alternative pathologies and subtle brain lesions and reduce exposure to ionizing radiation. It can also identify ischemia, hemorrhage, edema, and swelling. However, imaging with magnetic resonance venography has a high incidence of developing defects. The appearance of the radiographic image varies depending on the age of the thrombus. In patients with chronic thrombosis, echo or susceptibility-weighted imaging may be beneficial to demonstrate low signal in thrombosed sinuses.

The disadvantages of central venous thrombosis are:

• The hypoplastic (reduced development) appearance of the transverse sinus.

• The low signal intensity of the vein.

• The flow void is in contrast to enhanced MRI.

• Catheter Intra-Arterial DSA (Digital Subtraction Angiography)

It confirms the diagnosis when the imaging with CT and MR venography is inconclusive or with suspicion of dural arteriovenous fistula (abnormal opening between blood vessels). It is essential to identify the fistula early to facilitate treatment and embolization (a procedure using particles to block blood vessels). Imaging is beneficial if surgical interventions are planned.

• Ultrasonography

It is not a useful imaging technique for central venous thrombosis diagnosis. It aids in differentiation between the normal anatomic variant of hypoplastic sinus and thrombosed sinus. Color Doppler ultrasound can diagnose central venous thrombosis.

• Nuclear Imaging

It does not have a significant role in central venous thrombosis diagnosis. Reduced passage of blood in venous distribution can be observed.

How Is Cerebral Venous Thrombosis Treated?

The treatment for cerebral venous thrombosis includes

• Patients are administered intravenous fluids.

• Anticoagulants such as heparin are given. The medication is administered even during pregnancy.

• Thrombolytics (breakdown of blood clots)

• The infection occurring due to thrombosis is treated with antibiotics.

• Surgery is necessary for clot removal in several cases.

• Intracranial pressure can be lowered with medications like acetazolamide or intracranial pressure.

• Seizures are treated with antiepileptic medications.

• Visual acuity (clarity of vision) is monitored.

• The pressure inside the head is monitored and controlled. Decompressive craniectomy is recommended for patients with raised intracranial pressure in whom herniation (increased pressure causes protrusion of the brain) may develop.

• The patient is put on rehabilitation post-treatment. This recovery plan helps patients regain movement and control.

Taking warfarin or oral anticoagulant for 3 to 12 months is recommended.

What Are the Complications of Central Venous Sinus Thrombosis?

The complications of the disease include

• Speech problems.

• Trouble moving body parts.

• Vision defects.

• Headaches

• Developmental delays in children and newborns.

• Brain injury.

Conclusion

Cerebral venous thrombosis is an emergency condition that must be diagnosed early. The clinical features of the thrombotic disease can be inconclusive. Therefore, the role of imaging techniques becomes essential. CT venography and MRI venography are preferred modalities for diagnosis.