Diagnosis of cerebral venous thrombosis

Created 07/04/2021, last revision 06/11/2023

diagnosis of CVST is often difficult in the early stages; the temporal course and clinical symptoms are variable and often nonspecific
focal neurological symptoms occur in association with venous infarcts
exclude CVT in the presence of:
- intracranial hypertension syndrome
- atypical ischemias – especially those with atypical localization, not respecting arterial territories, and featuring hemorrhagic component or edema
- first epileptic seizure (especially in young women)
- direct signs of thrombosis on Non-Contrast Computed Tomography (NCCT)

Neuroimaging

neuroimaging is essential for the diagnosis of CVT
CT is widely available and is the most commonly used baseline imaging modality, although MRI with venous TOF sequence is preferred (especially in pregnancy)

When should you think about cerebral venous sinus thrombosis?
Direct signs of thrombus in the vein/dural sinus	dense clot sign (delta sign)
	cord sign
	empty delta sign (contrast-enhanced CT)
	absent flow void in T2/FLAIR
Indirect signs	lateral, parasagittal, and bithalamic infarcts with/without hemorrhage cortical edema peripheral lobar hematomas cashew nut sign (juxtacortical hemorrhage) (Moudrous, 2015)

non-contrast CT scan (NCCT) of the brain is normal in up to 30% of cases
always evaluate separately
- non-contrast CT images (hyperdensity sign – cord sign, dense clot sign) – positive in 25%
- contrast-enhanced CT images (empty delta sign) – positive in 16-46%
indirect signs of thrombosis: edema, an atypically located infarct, often with a hemorrhagic component
a hyperdense sign may be false-positive; additional signs are required for diagnosis
- a false-positive finding in polyglobulia
- typical values with CVT are of > 70 HU [Black, 2011]
a CT scan may detect associated inflammatory changes (such as otitis, mastoiditis, sinusitis)

CT venography (CTV) is a reliable alternative to MR venography (MRV) or DSA (ESO guidelines 2017)
- a time delay of 25-45 seconds is recommended in comparison to CTA
- sensitivity for dural sinus thrombosis is up to 95% compared to DSA
- alternative to MRV – MRI offers superior visualization of thrombus and parenchymal changes
- disadvantages:
  - as with DSA, there is a problem with differentiating between sinus hypoplasia and aplasia (5-20%)
  - exposure to radiation and contrast media
  - limited diagnostic value for cortical vein thrombosis

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consider possible anatomical variants of the venous system, including hypoplasia or absence of some of the vessels
a specific indicator for CVST diagnosis is the presence of a “stop sign” (abrupt termination of a sinus or vein) accompanied by collateral circulation and congestion of cortical veins (characterized by dilation, tortuosity)
DSA may show associated cortical vein thrombosis and possibly arterio-venous fistula as well as deep vein thrombosis
in addition, DSA shows the dynamics and drainage pattern in the occluded area
- after applying the contrast agent, the venous system is completely visualized within 7-8 seconds
- in thrombosis, the filling of the veins is delayed or absent
currently, MRV and CTV dominate the diagnostic workup, and DSA is reserved for interventional procedures when conservative therapy fails

the method has low sensitivity and specificity
- indirect signs are mostly evaluated: flow acceleration (> 40 cm/s) due to collateral circulation
the sigmoid sinus (SS) thrombosis may be monitored by examining flow in the ipsilateral internal jugular vein (IJV)
more information on TCCD examination of cerebral veins and sinuses is here

normal D-dimer levels: 0.068-0.494 mg/L
may serve as an important screening tool (with sensitivity > 95%); testing D‐dimer together with fibrinogen may increase specificity
- the sensitivity and specificity using D-dimer alone were 94·1% and 97·5%, whereas those for D-dimer + fibrinogen were 67·6% and 98·9% [Meng,2013]
- elevated levels can occur in various conditions, such as infection, trauma, or malignancy
a normal level makes the diagnosis of acute thrombosis unlikely but does not definitively exclude it (AHA/ASA 2011 IIb/B) [Kosinki, 2005] [Lalileve,2003]
- positive in ~ 94% of patients with CVT (ESO guidelines 2017)
- a false-negative result may be seen in isolated headaches and prolonged thrombosis lasting > 1 week
on the other hand, false-positive results are common (see below)
after anticoagulation therapy, D‐dimer levels gradually normalize; fibrinogen levels may remain elevated for several weeks

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perform a lumbar puncture to rule out an infectious etiology if suspected
evacuation of ∼ 20-30 mL of cerebrospinal fluid (CSF) may alleviate pain or prevent loss of vision
typical signs of venous thrombosis include increased opening pressure, proteinorhachia, and occasionally mild pleocytosis
- mild pleocytosis may lead to misdiagnosis of neuroinfection
lumbar puncture is contraindicated in the presence of an expansive parenchymal lesion

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pathological findings are predominantly associated with parenchymal lesions
in mental status is altered, rule out nonconvulsive status epilepticus (NCSE)

high-flow dural A-V fistula can lead to venous congestion and subsequent hemorrhagic infarction (which can be difficult to distinguish from a venous thrombosis)

headache and encephalopathy are less common in ischemic stroke
compared to ischemic stroke, infarct lesions in CVST differ in shape and location
in CVST, hemorrhagic transformation and collateral edema are commonly observed on baseline imaging

look for signs of inflammation – fever, leukocytosis with elevated CRP and ESR
positive CSF findings (pleocytosis, elevated protein level)
consider a combination of venous thrombosis and neuroinfection (in such instance, thrombosis is likely triggered by the infection)

typical symptoms and signs of IIH include
- headache
- abducens palsy
- papilledema, visual disturbances (e.g., transient visual obscurations)
venous thrombosis should be excluded via MR venography (MRV) or CT venography (CTV)
lumbar puncture rules out infection and confirms elevated CSF pressure (through direct measurement of the opening pressure)
symptoms atypical for IIH:
- encephalopathy
- focal neurological deficits
- seizures