Epidemiology

Cerebral venous sinus thrombosis (CVST) is the thrombosis of dural venous sinuses and/or cerebral veins. It accounts for 0.5% of all strokes. It occurs predominantly in the younger population (usually < 50 years old, median age of 37). Female-to-male ratio is 3 to 1, likely secondary to sex-specific thrombogenic states including pregnancy, puerperium, oral contraceptive pill use, and hormonal therapy.¹

Pathogenesis

Venous thrombosis can cause localized edema and infarction. Thrombosis of major sinuses or the deep venous system (Figure 11.1) can lead to global edema and intracranial hypertension due to the impairment of CSF drainage.

Figure 11.1 Frequency of cerebral venous thrombosis by site.

Adapted from: Stam J. Thrombosis of the cerebral veins and sinuses. N Engl J Med 2005; 352: 1791–1798.²

Risk Factors³

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  At least one risk factor is detected in 85% of cases.

  
  
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  Transient risk factors include pregnancy, puerperium, infections (e.g., meningitis, sinusitis, mastoiditis, otitis media), procedure (e.g., intracranial surgery, lumbar puncture), dehydration, exposure to drugs, and head trauma.

  
  
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  CVST can also occur in association with cancer, and may develop before the cancer is diagnosed.

  
  
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  Chronic risk factors include acquired or inherited thrombophilia (e.g., antiphospholipid syndrome, factor V Leiden mutation, factor II mutation (prothrombin G20210A), protein C/S deficiencies).

  
  
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  Multiple risk factors are commonly encountered in one patient.

Clinical Picture

Headache is the most common symptom (80–90% of cases) and, when isolated, can lead to the diagnosis being overlooked. Four clinical syndromes are frequently seen with CVST, and these can be found in isolation or combined:^{4, 5}

1. 
   

   1. seizures (40%)

   
   
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   2. intracranial hypertension (e.g., headache, altered sensorium, diplopia, papilledema, bilateral sixth nerve palsies) (37%)

   
   
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   3. focal neurological deficit (20–37%)

   
   
4. 
   

   4. encephalopathy (20–30 %)

Hemorrhagic conversion of a venous infarct occurs in up to 40% of cases. It has been associated with older age, female sex, and acute onset.

Diagnosis

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  A high level of suspicion is needed to make the correct diagnosis. Imaging is crucial. Clues to diagnosis on initial imaging include bilateral paramedian hypodensities, infarction that does not respect an arterial territory, or parenchymal hemorrhage in an unusual location adjacent to a venous sinus.^{6, 7}

  
  
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  The preferred neuroimaging modality is MRI and MR venography (MRV). The SWI sequence of the MRI allows identification of isolated cortical venous thrombosis. Contrast MRV is more sensitive than time-of-flight MRV.

  
  
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  CT and CT venography (CTV) can also be used but are not as sensitive as MRI. On CT head, a “dense cord” sign might be seen (hyperdense thrombosed vein or sinus). An “empty delta” sign can be seen on contrast CT. CTV is not sensitive enough to detect cortical vein thromboses.

  
  
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  Conventional angiography is rarely used unless non-invasive imaging is equivocal or it is needed for therapeutic intervention. Also, the altered venous drainage associated with CVST can result in a chronic dural fistula, which can only be diagnosed by arteriography including the external carotid and vertebral arteries.

Acute Management

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  Anticoagulation – Initial systemic anticoagulation using either unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) is the mainstay of therapy, despite the limited evidence coming from two small randomized studies.^{8, 9} In one study, LMWH was seen to be more efficacious (better functional outcome at 6 months) and perhaps safer (less risk of ICH) than UFH. It is recommended to anticoagulate even in the face of hemorrhagic transformation or venous-related ICH. The purpose of anticoagulation is to prevent extension of the thrombus and facilitate recanalization.

  
  
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  Osmotherapy – Osmotherapy can be very effective in reducing vasogenic edema secondary to venous obstruction. It should be started as soon as edema begins to produce mass effect on adjacent structures (see Chapter 7).

  
  
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  Endovascular therapy – Intra-arterial thrombolysis and mechanical thrombectomy (using stent retrievers, aspiration devices, or balloon venoplasty) have been used but efficacy has not been established because of the lack of randomized trials.^{10, 11} Endovascular therapy is used when systemic anticoagulation is unsuccessful at recanalization and the patient’s neurological status is deteriorating.

  
  
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  Decompressive hemicraniectomy – Very limited data exist on this therapy. It remains an option for patients who develop refractory intracranial hypertension related to malignant hemispheric edema/infarction.¹² The potential for expansion of the intracranial hemorrhage is a worrisome complication of the surgery.