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Cerebral Sinus Thrombosis
(Dural Venous Thrombosis)

Pathology || Signs and Symptoms || Diagnosis || Treatment || Overview ||
Related Articles || References and Resources || Leave a Comment || Search

Pathology





The brain contains large blood vessel-like structures that drain venous blood back to the heart. These are collectively known as "cerebral sinuses". There are nine of them total: the superior sagittal sinus, inferior sagittal sinus, a pair of transverse sinuses, a pair of sigmoid sinuses, straight sinus, cavernous sinus, a pair of superior petrosal sinuses, a pair of inferior petrosal sinuses, and the occipital sinus.

Just like other veins in the body, the cerebral sinuses can form blood clots (the technical term for a blood clot is actually a "thrombosis", hence the name). However, unlike blood clots that form in the veins of the upper and lower extremities, blood clots in the cerebral sinuses are relatively uncommon.

The exact cause of a dural venous thrombosis is not always discovered. However, there are numerous risk factors associated with their development. They include inherited defects in proteins responsible for blood clot formation. These defects are collectively known as "thrombophilias", which in Latin means "thrombus loving".

In addition, patients with a kidney condition known as nephrotic syndrome are at increased risk. In this condition patients piss out proteins responsible for keeping the blood clotting system at bay. The end result? An increased propensity to form unnecessary clots.

Infections such as mastoiditis and meningitis can cause inflammation of the sinuses, which can result in blood clot formation. Trauma to the head can also cause clot formation. In addition, that beautiful parasitic infection known as pregnancy (I joke of course!) also increases the risk of developing blood clots. On the flip side, many commonly used birth control pills, especially those containing estrogen, can also increase a person's risk.

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Signs and Symptoms

Depending on the severity of the clot, everything from a mild headache (the most common presenting symptom) to death is fair game when it comes to cerebral sinus thrombosis. Patient's with severe headaches may also have associated nausea and vomiting secondary to elevated intracranial pressures. Decreased mental status (ie: confusion, coma, etc.) is also sometimes observed.

In terms of signs and symptoms, it is also important to remember that not all sinuses are created equal. For example, thrombosis in the superior sagittal sinus can present with leg weakness secondary to edema (ie: swelling) of the adjacent motor cortex.

If a clot forms in the cavernous sinus it may cause dysfunction of the third, fourth, fifth, and/or sixth cranial nerves. In addition, when blood "pools up" behind a clot in one of the venous sinuses it can cause increased swelling (aka: edema) in the surrounding brain tissue. If severe enough a venous stroke can occur, which can cause permanent neurological injury.

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Diagnosis

With todays modern imaging studies, MRI, and more specifically MR venography  has become a crucial diagnostic aid in diagnosing and managing cerebral sinus thrombosis.

An example of an MR venogram is shown in the picture below. Other commonly used tests include traditional angiograms, in which radio-opaque dye is injected directly into the sinuses through catheters inserted in the groin. Finally, CT scans are also commonly obtained, especially to evaluate for possible co-existent hemorrhage.

MRV of Cerebral Sinus Thrombosis

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Treatment

Treatment is usually with a blood thinning medication known as heparin. It is delivered through an IV and helps prevent further clot formation. If a venous stroke is present the use of blood thinning medications must be weighed against the possibility of causing bleeding into the stroked brain tissue (ie: this is known as "hemorrhagic" transformation of a stroke). Aggressive hydration with normal saline is also often advocated.

Treating other underlying co-problems such as seizures and increased intracranial pressure is also an important part of managing patients with cerebral sinus thrombosis.

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Overview

Cerebral sinus thrombosis is a blood clot in one or more of the large venous draining systems of the brain. They are uncommon and can present with everything from a mild headache to coma and death. Diagnosis is made most commonly with MRI. Treatment is based on preventing further clot formation with heparin and aggressive hydration.

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Related Articles

- Meningioma

- Colloid cysts of the brain

- Stroke (cerebrovascular accident)

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References and Resources

(1) Xu H, Chen K, Lin D, et al. Cerebral venous sinus thrombosis in adult nephrotic syndrome. Clin Nephrol. 2010 Aug;74(2):144-9. Review.

(2) Dlamini N, Billinghurst L, Kirkham FJ. Cerebral venous sinus (sinovenous) thrombosis in children. Neurosurg Clin N Am. 2010 Jul;21(3):511-27.

(3) Ju YE, Schwedt TJ. Abrupt-onset severe headaches. Semin Neurol. 2010 Apr;30(2):192-200. Epub 2010 Mar 29.

(4) Kamal AK. Thrombolytic therapy in cerebral venous sinus thrombosis. J Pak Med Assoc. 2006 Nov;56(11):538-40.

(5) Greenberg MS. Handbook of Neurosurgery. Sixth Edition. New York: Thieme, 2006.

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The sixth cranial nerve (aka: abducens nerve) courses on the innermost aspect of the cavernous sinus. It controls the lateral rectus muscle of the eye, which allows your eye to move away from your nose.
The fifth cranial nerve (aka: trigeminal nerve) controls sensation to the face. It has 3 branches, of which 2 course along the side of the cavernous sinus. Damage to these nerves can result in decreased sensation to the forehead and maxillary region of the face.
The fourth cranial nerve (aka: trochlear nerve) controls the superior oblique muscle of the eye, which allows the eye to intort and depress. Clinically, when a patient with a fourth nerve deficit looks towards the nose, the eye looking towards the nose will move upwards.
The third cranial nerve (aka: oculomotor nerve) controls the medial, superior, and inferior rectus muscles of the eye, as well as the inferior oblique muscle. Damage to the nerve results in an eyeball that is "down and out".