Cerebral Venous Thrombosis (CVT)
Last updated: September 5, 2017
- thrombosis of venous sinuses, superficial or deep cerebral veins.
1% of all strokes.
female-to-male ratio 1.29-3 : 1
any age (newborn to elderly patients); 80% patients are < 50 yrs; age distribution:
men - uniform age distribution;
women - 61% aged 20-35 yrs (may be related to pregnancy or oral contraceptives)
mean age at presentation is nearly 1 decade younger in women compared to men (34 years vs. 42 years).
Infection extension from paranasal sinuses, middle ear (via emissary veins), face, oropharynx → suppurative intracranial thrombophlebitis.
N.B. orbital veins (drain from middle third of face, including paranasal sinuses) have no valves - allow infection passage both anterograde and retrograde!
may be associated with epidural abscess, subdural empyema, meningitis, cranial osteomyelitis.
frontal sinuses are most common source.
most commonly - lateral and cavernous sinuses.
Staphylococcus aureus is most common.
mild closed injury ÷ depressed skull fracture (occludes dural sinus)
iatrogenic - dural taps, infusions into internal jugular vein.
Tumors (e.g. meningioma, neuroblastoma).
antiphospholipid syndrome, protein S and C deficiencies, antithrombin III deficiency, lupus anticoagulant, Leiden factor V mutation.
paroxysmal nocturnal hemoglobinuria, thrombotic thrombocytopenic purpura, sickle cell disease, polycythemia.
pregnancy and puerperium!!!
disseminated malignancies (paraneoplastic hypercoagulation)
sarcoidosis, inflammatory bowel diseases (Crohn), collagenoses (incl. corticosteroids used in treatment).
vasculitis (such as Behcet syndrome).
nephrotic syndrome, hepatic cirrhosis.
dehydration, cachexia (“marantic” thrombosis in infancy) - superior sagittal sinus is most common.
Medications: oral contraceptives (incl. 3rd-generation), corticosteroids; ε-aminocaproic acid, L-asparaginase, heparin (thrombotic thrombocytopenia with venous sinus thrombosis).
Cerebral venous thrombosis is uncommon cause of cerebral infarction (relative to arterial disease).
venous strokes : arterial strokes ≈ 1 : 62.5
venous occlusion → tissue congestion → early severe vasogenic brain edema → venous infarction → cytotoxic edema:
venous sinus thrombosis - infarction in cortex and adjacent white matter;
deep cerebral vein thrombosis - infarction in basal ganglia, thalamus.
venous sinus system itself lacks valves, permitting retrograde propagation of clots - thrombosis from dural sinuses may progress (esp. in septic thrombosis) to cortical veins.
obstruction of cortical veins (e.g. vein of Labbé) can produce significant damage.
although unusual, cortical vein thrombosis may be seen in absence of dural sinus involvement.
back-transmission of high pressure into capillary bed usually results in significant hemorrhagic component.
SAH also may be presenting feature (due to venous hypertension).
CVT should be considered in workup of SAH, esp. when basilar cisterns are not involved!
if sinus occlusion occurs gradually (as by neoplastic invasion), collateral drainage routes (incl. scalp veins) are recruited, thus avoiding cerebral edema and ICP↑.
venous thrombi are rich in RBCs and fibrin but poor in platelets ("red thrombus") → replaced by fibrous tissue with time.
Venous infarcts do not conform to arterial territories, are often hemorrhagic and multifocal.
superior sagittal sinus (70%, but less common site of infective thrombosis) – bilateral parasagittal more or less symmetric infarcts – most severe damage!
transverse (lateral) sinuses
inferior sagittal sinus, straight sinus, petrosal sinuses, vein of Galen - usually involved by secondary extension.
course is more severe in septic thrombosis.
course is mildest in isolated cortical vein thrombosis.
Signs of ICP↑:
headache - most common symptom!; increases over several days; thunderclap headache (usually indicates SAH) may be seen in sinus thrombosis!!!
nausea & vomiting
normal ÷ decreased level of consciousness (may progress to coma).
Focal neurological deficit (75% patients) - depending on area involved as thrombus extends to cortical veins (CN syndromes, hemiparesis, facial weakness, aphasia, ataxia, hemianopia, deafness, etc).
N.B. focal neurologic signs may be entirely absent with ICP↑ pressure as only presenting sign!
seizures are more common than in arterial strokes!; can be recurrent.
isolated intracranial hypertension (mimicking pseudotumor cerebri)
focal neurological signs (simulating arterial strokes or seizures)
cavernous sinus syndrome.
Symptoms related to area of thrombosis:
Superior sagittal sinus thrombosis
weakness in lower extremity (unilateral or paraparesis) → hemiparesis (secondary to clot extension into cerebral veins).
in infants - forehead edema, vein engorgement in area of anterior or posterior fontanels (caput medusae).
bilateral involvement can produce stupor early in course.
seizures in > ½ patients.
course is frequently fulminant and prognosis guarded, although complete recovery may occur.
Lateral sinus thrombosis
usually secondary to pediatric otitis media and mastoiditis (most patients are febrile with earache).
swelling over mastoid region with distention of superficial veins.
Griesinger sign - mastoid emissary vein thrombosis due to thrombus extension from sigmoid sinus.
pseudotumor cerebri–like picture (ICP↑) – more common with right sinus occlusion (in most individuals, right sinus drains greater portion of brain).
may produce otitic hydrocephalus.
most common focal sign – CN6 palsy.
extension into jugular bulb → tenderness over jugular vein in neck, jugular foramen syndrome (Vernet): CN 9-11
Cavernous sinus thrombosis
septic thrombosis (S. aureus 66%) is associated with bacterial sinusitis (sphenoidal or ethmoidal) or orbital cellulitis; nonseptic thrombosis is rare!
involves only one sinus at onset but rapidly spreads (via circular sinus) to opposite side.
onset is usually sudden and dramatic - patient appears acutely ill with fever; > ½ patients have change in mental status.
cranial nerve palsies (compressive phenomenon) → variable ophthalmoplegia (esp. early CN6 palsy), ptosis, decreased sensation in CN51-2 divisions.
obstruction of ophthalmic veins → periorbital edema (!), proptosis, chemosis, papilledema with hemorrhages around disc; orbits are painful to pressure.
septic thrombosis has high mortality.
absence of flow void in venous channels.
N.B. acute thrombus can appear hypointense on spinT2 (mimics flow void!!!); slow flowing blood may appear bright (mimics thrombus); H: MRV
edema and infarct (unilateral or bilateral or single or multifocal) that does not follow distribution of expected arterial occlusion.
hemorrhagic infarction is commonly found (because of increased pressure in draining veins).
chronic organizing thrombus develops significant neovascularity - enhances strongly demonstrating "frayed" or "shaggy" appearance.
Transverse sinus thrombosis:
A. Unenhanced coronal T1-MRI - high signal in right cerebellar hemisphere due to hemorrhage; absence of flow void and high signal in right transverse sinus (arrow).
B. Enhanced coronal T1-MRI - hemorrhagic infarct better defined and thrombus in right transverse sinus (arrow) is demarcated by enhancing walls of sinus.