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| ==Natural History, Complications and Prognosis== | | ==Natural History, Complications and Prognosis== |
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| ==Diagnosis==
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| ===Laboratory Findings===
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| The diagnosis may be suspected on the basis of the symptoms (e.g. the combination of headache, signs of raised [[intracranial pressure]] and focal neurological abnormalities), or when alternative causes of headache and neurological abnormalities (such as a [[subarachnoid hemorrhage]]) have been excluded.<ref name=Stam2005/>
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| ;CT, MRI and angiography
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| There are various investigations that may detect cerebral sinus thrombosis. [[Cerebral oedema]] and venous infarction may be apparent on any modality, but for the detection of the thrombus itself, the most commonly used tests are [[computed tomography]] (CT) and [[magnetic resonance imaging]] (MRI), both using various types of [[radiocontrast]] to perform a [[venogram]]. [[Cerebral angiography]] may demonstrate smaller clots, and obstructed veins may give the "corkscrew appearance".<ref name=Stam2005/>
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| [[Computed tomography]], with [[radiocontrast]] in the venous phase (''CT venography'' or CTV), has a detection rate that in some regards exceeds that of MRI. The test involves injection into a vein (usually in the arm) of a radioopaque substance, and time is allowed for the bloodstream to carry it to the cerebral veins - at which point the scan is performed. It has a [[sensitivity (tests)|sensitivity]] of 75-100% (it detects 75-100% of all clots present), and a [[specificity (tests)|specificity]] of 81-100% (it would be incorrectly positive in 0-19%). In the first two weeks, the "empty delta sign" may be observed (in later stages, this sign may disappear).<ref name=Smith2007>{{cite journal |author=Smith R, Hourihan MD |title=Investigating suspected cerebral venous thrombosis |journal=BMJ |volume=334 |issue=7597 |pages=794–5 |year=2007 |pmid=17431266 |doi=10.1136/bmj.39154.636968.47}}</ref>
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| [[Magnetic resonance angiography|Magnetic resonance venography]] employs the same principles, but uses MRI as a scanning modality. MRI has the advantage of being better at detecting damage to the brain itself as a result of the increased pressure on the obstructed veins, but it is not readily available in many hospitals and the interpretation may be difficult.<ref name=Smith2007/>
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| ;D-dimer
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| A 2004 German study suggested that the [[D-dimer]] blood test, already in use for the diagnosis of other forms of thrombosis, was abnormal (above 500 μg/l) in 34 out of 35 patients with cerebral sinus thrombosis, giving it a [[sensitivity (test)|sensitivity]] of 97.1%, a [[negative predictive value]] of 99.6%, a [[specificity]] of 91.2%, and a positive predictive value of 55.7%. Furthermore, the level of the D-dimer correlated with the extent of the thrombosis.<ref>{{cite journal |author=Kosinski CM, Mull M, Schwarz M, ''et al'' |title=Do normal D-dimer levels reliably exclude cerebral sinus thrombosis? |journal=Stroke |volume=35 |issue=12 |pages=2820–5 |year=2004 |pmid=15514174 |doi=10.1161/01.STR.0000147045.71923.18}}</ref> A subsequent 2005 study performed in France showed that 10% of patients with confirmed thrombosis had a normal D-dimer, and in those who had presented with only a headache 26% had a normal D-dimer. The study concludes that D-dimer is not useful in the situations where it would make the most difference (low-probability settings).<ref>{{cite journal |author=Crassard I, Soria C, Tzourio C, ''et al'' |title=A negative D-dimer assay does not rule out cerebral venous thrombosis: a series of seventy-three patients |journal=Stroke |volume=36 |issue=8 |pages=1716–9 |year=2005 |pmid=16020765 |doi=10.1161/01.STR.0000173401.76085.98}}</ref>
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| ===Further tests===
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| In most patients, the direct cause for the cerebral sinus thrombosis is not readily apparent. Identifying a source of infection is crucial, but it is common practice to screen for various forms of [[thrombophilia]] (a propensity to form blood clots).<ref name=Stam2005/>
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| ==Treatment== | | ==Treatment== |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Keywords and synonyms: Cerebral venous thrombosis, cerebral sinus thrombosis, superior sagittal sinus thrombosis, dural sinus thrombosis and intracranial venous thrombosis
Overview
Pathophysiology
Epidemiology and Demographics
Risk factors
Natural History, Complications and Prognosis
Treatment
Various studies have investigated the use of anticoagulation (suppression of blood clot formation) in cerebral venous sinus thrombosis. Before these trials, there was a concern that small areas of hemorrhage would bleed further as a result of treatment. The European Federation of Neurological Societies (EFNS) recommends heparin or low molecular weight heparin in the initial treatment, followed by warfarin, provided there are no other bleeding risks that would make these treatments unsuitable.[1] The duration of warfarin treatment depends on the circumstances and underlying causes of the condition. If the thrombosis developed under temporary circumstances (e.g. pregnancy), three months are regarded as sufficient. If the condition was unprovoked but there are no clear causes or a "mild" form of thrombophilia, 6 to 12 months is advised. If there is a severe underlying thrombosis disorder, warfarin treatment may need to continue indefinitely.[1]
Thrombolysis (removal of the blood clot with "clot buster" medication) has been described, either systemically by injection into a vein or directly into the clot during angiography. The 2006 EFNS guideline recommends that thrombolysis is only used in patients who deteriorate despite adequate treatment, and other causes of deterioration have been eliminated. It is unclear which drug and which mode of administration is the most effective. Bleeding into the brain and in other sites of the body is a major concern in the use of thrombolysis.[1]
Raised intracranial pressure, if severe or threatening vision, may require therapeutic lumbar puncture (removal of excessive cerebrospinal fluid), medication (acetazolamide), or surgical treatment (optic nerve sheath fenestration or shunting).[2] In certain situations, anticonvulsants may be used prophylactically (i.e. to prevent seizures); these are focal neurological problems (e.g. inability to move a limb) and/or focal changes of the brain tissue on CT or MRI scan.[1]
References
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