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CVT

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Cerebral venous thrombosis

Epidemiology

  • uncommon but probably under-recognised
  • slight female preponderance
  • usual onset in 3rd or 4th decades

Aetiology

Endocrine disorders

  • oral contraceptive. Only identifiable predisposing factor in 8% of cases in largest series
  • pregnancy/puerperium. Symptoms usually occur in puerperium
  • androgen therapy, danazol

Haematological/immunological

  • antiphospholipid syndrome. IgG more likely than IgM abs to be associated with CVT
  • anaemia
  • prothrombotic states: antithrombin III deficiency, protein S deficiency, protein C deficiency
  • leukaemia
  • lymphoma
  • myeloproliferative disorders
  • paroxysmal nocturnal haemoglobinuria
  • sickle cell disease
  • TTP

Connective tissue and other inflammatory conditions

Infective

Neoplastic

Malignancies can induce thrombosis by a local, metastatic or non-metastatic action

  • cerebral metastases
  • disseminated malignancy
  • glomus tumour
  • meningioma
  • visceral malignancy. Assoc with CVT in the absence of macroscopic cerebral metastases

Miscellaneous

  • cardiac failure
  • jugular vein thrombosis/ligation

Clinical features

  • acute/subacute/chronic presentation
  • headache (>75%)
  • papilloedema (>50%)
  • most common pattern of presentation is with a benign intracranial hypertension-like syndrome especially in patients with a history extending over several weeks
  • the shorter the history the more likely the presence of focal signs
  • ± VI palsy: usually false localizing sign but may be result of extension of thrombus into inferior petrosal sinus. Cavernous sinus thrombosis may lead to III, IV and VI palsies
  • ± transient cortical ischaemia with short-lived motor or sensory signs or dysphasia. Due to extension of thrombus into superficial cortical veins. These focal deficits can mimic arterial transient ischaemic attacks but accompanying features (headache, papilloedema and young age of patient) should provide a guide to their venous origin
  • established venous cortical infarction is frequently heralded by seizures
  • ± meningism: reflects haemorrhagic nature of lesion
  • impairment or fluctuation of consciousness

Investigations

CT

  • characteristic findings of sagittal sinus thrombosis: filling defect within posterior portion of sinus on contrast scan, if thrombus extends that far. Results in "empty delta/triangle sign. Only 30% of cases and can occur in normal patients with a high division of the superior sagittal sinus
  • small ventricular system
  • reduction of sulcal pattern due to swelling
  • haemorrhagic venous infarcts
  • intense enhancement of falx and tentorium (due developing venous collaterals)
  • thrombosed cortical veins (cord sign)
  • low density changes in basal ganglia if straight sinus occlusion has occurred
  • NB unenhanced CT almost always normal in absence of established venous infarction and even contrast CT has a false negative rate of 10-30%

MRI

  • appearances evolve over time
  • in acute phase (first 5 days): absence of normal venous flow void on T1 and T2 weighted images. Thrombus itself appears isointense and hypointense respectively
  • 5-15 days: hyperintense signals within occluded sinus on T1 and T2 sequences
  • >15 days: signal intensity decreases in those in whom obstruction continues whilst in cases of recanalisation venous flow void reappears
  • venous phase MRA shows characteristic filling defects in principal dural sinuses. Non-invasive and does not require administration of contrast

Angiography

  • IV DSA gives poor definition images delineating only the principal sinuses. Cannot demonstrate cortical venous occlusion. Requires administration of a large volume of contrast and is associated with a up to 10% incidence of systemic reactions to contrast
  • IA angiography ±DSA provides high definition images but is associated with small (<5% risk of neurological complications. Filling defects within dural sinuses or their complete occlusion demonstrated on delayed venous phase projections. Can also demonstrate appearance of deep and superficial cortical collateral veins (‘corkscrew veins")
  • superceded by MRI except in very obese or claustrophobic patients, or unstable ICU patients

Lumbar puncture

  • to exclude other pathologies such as meningitis and SAH
  • CSF analysis may shed light on possible aetiology. CSF in CVT may be normal or there may be an increase in protein, white cells or red cells, alone or in combination
  • measurement of pressure may be helpful in establishing a baseline and also as a therapeutic measure if vision is threatened

Differential diagnosis

Management

  • Influenced by aetiology and clinical features
  • patients with BIH-like syndrome only: diuretics may be sufficient to control raised ICP ± dexamethasone ± repeated LP. Optic nerve fenestration or lumbar-peritoneal shuntion if these measures fail and vision deteriorates
  • preliminary evidence that heparin improves outcome and that it is not necessarily contraindicated in the presence of haemorrhagic venous infarction. LMW heparin and warfarin currently being evaluated in Dutch-European Cerebral Sinus Thrombosis Trial. Until resuls available seems reasonable to reserve anticoagulation for those patients who present early, have evidence of extensive or progressing thrombosis, deteriorate despite diuretics and steroids or have clinical features of cortical vein involvement (fixed or fluctuating focal deficit, fits, impaired consciousness
  • case reports of successful response to local administration of thrombolytic agents via venous catheters

Outcome

  • mortality 5-30%
  • amongst survivors minority develop permanent deficit (eg limb weakness, epilepsy, optic atrophy)

Further reading

Martin PJ, Enevoldson TP. Cerebral venous thrombosis. Postgrad Med J, 1996; 72:72-76

© Charles Gomersall December 1999

 

©Charles Gomersall, February, 2015 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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