Cerebral venous thrombosis
Citation, DOI and article data
Cerebral venous thrombosis (CVT) refers to occlusion of venous channels in the cranial cavity, including dural venous thrombosis, cortical vein thrombosis and deep cerebral vein thrombosis. They often co-exist and the clinical presentation among them is very similar and non-specific. Furthermore, diagnostic imaging features can be subtle.
Cerebral venous thrombosis is a rare condition accounting for approximately 0.5% of all cases of cerebrovascular disease worldwide 8. Demographics of affected patients reflects underlying predisposing factors, which are identified in the majority of cases (87.5%) with many patients having more than one coexistent risk factors 2:
- oral contraceptive pill: very common cause in female patients <50 years of age 2
- prothrombotic hematological conditions: 35% 2
- e.g. prothrombin 20210 (factor II) mutation 7
- local factors
- systemic illness
- idiopathic: ~12% 2
Unlike most other intracranial vascular conditions, the presentation can be highly variable and range from essentially asymptomatic to coma and death, and can also mimic a host of conditions 1.
- headaches (89-91%) 8
- decreased/altered conscious state
- decreased/altered vision
CVT pathogenesis remains poorly understood 5. There is an extensive list of known risk factors, already mentioned above.
The lesion volume is related to the development of collateral veins in the affected venous segment. Venous hypertension from a poor outflow can lead to edema, cerebral venous infarction (~50% of cases 1) and even hemorrhage.
Unenhanced CT is usually the first imaging investigation performed given the nonspecific clinical presentation in these cases.
Non-contrast CT, when not associated with venous hemorrhage or infarction can be a subtle finding, relying on hyperdensity of the sinus being identified 1,5. Thrombus can appear as a hyperdense vein or sinus for the first 7-14 days; this is an accurate sign when present 6.
With contrast administration, especially with a CT venogram, a filling defect in a sinus is sought. When in the sagittal sinus it is referred to as the 'empty delta sign'. CTV has a reported sensitivity of 95% compared to DSA as the gold standard 1.
Filling defects should not be confused with Pacchionian bodies (arachnoid granulations) which can be seen in essentially all dural sinuses and are especially common in the superior sagittal sinus and transverse sinus.
MRI is able to both visualize the clot as well as the sequelae.
The clot acutely is isointense on T1 and hypointense on T2 (this can mimic a flow void), with subacute clot becoming hyperintense on T1.
Cerebral edema can be identified even in the absence of neurological dysfunction or infarction 1.
MRV will demonstrate a lack of flow. 2D time of flight (TOF) venography is routinely performed in suspected cases. Contrast MR venography is more sensitive in detecting dural venous sinus thrombosis than TOF venography. Hypoplastic dural sinuses and low flow areas remain a major problem with 2D TOF.
Although not used routinely in clinical practice, whole brain CT perfusion may assist in establishing the diagnosis of CVT by detecting perfusion abnormalities that do not correspond with arterial territories 9.
Although digital subtraction angiography (DSA) has historically been the gold standard, the relative lack of experienced angiographic skills and invasive nature of the examination has led to a dramatic decline in its use as a primary mode of diagnosing cerebral venous thrombosis.
Treatment and prognosis
In ~50% of cases, cerebral venous thrombosis progresses to venous infarction 1. Unlike arterial infarcts, venous infarcts usually present after some days 1:
- <2 days of symptom onset: 30%
- 2-30 days: 50%
- >30 days: 20%
The mainstay of treatment is heparin, even in the setting of hemorrhagic venous infarction 2,4. The natural history of cerebral venous thrombosis is highly variable, with some patients having minimal or no symptoms and an uneventful recovery (~65%), whereas others have a fulminant course culminating in extensive venous infarction and dependency or death (~20%) 2.
Interventional neuroradiologists can perform catheter-directed thrombolysis by using targeted thrombolytics in the affected sinuses.
Not surprisingly coma, hemorrhagic venous infarcts and co-existing malignancy correlate with poor outcome 2. Deep cerebral venous thrombosis also has a negative impact on prognosis due to the usually bilateral involvement of the thalami 3.
Dural arteriovenous fistula and increased CSF pressure have been reported as possible complications after cerebral venous thrombosis.
- 1. Rodallec MH, Krainik A, Feydy A et-al. Cerebral venous thrombosis and multidetector CT angiography: tips and tricks. Radiographics. 2006;26 Suppl 1 : S5-18. doi:10.1148/rg.26si065505 - Pubmed citation
- 2. Ferro JM, Canhão P, Stam J et-al. Prognosis of cerebral vein and dural sinus thrombosis: results of the International Study on Cerebral Vein and Dural Sinus Thrombosis (ISCVT). Stroke. 2004;35 (3): 664-70. doi:10.1161/01.STR.0000117571.76197.26 - Pubmed citation
- 3. Herrmann KA, Sporer B, Yousry TA. Thrombosis of the internal cerebral vein associated with transient unilateral thalamic edema: a case report and review of the literature. AJNR Am J Neuroradiol. 2004;25 (8): 1351-5. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 4. Bousser MG. Cerebral venous thrombosis: nothing, heparin, or local thrombolysis? Stroke. 1999;30 (3): 481-3. Stroke (link) - Pubmed citation
- 5. Poon CS, Chang JK, Swarnkar A et-al. Radiologic diagnosis of cerebral venous thrombosis: pictorial review. AJR Am J Roentgenol. 2007;189 (6_supplement): S64-75. doi:10.2214/AJR.07.7015 - Pubmed citation
- 6. Zeina AR, Kassem E, Klein A et-al. Hyperdense cerebral sinus vein thrombosis on computed tomography. West J Emerg Med. 2011;11 (2): 217. Free text at pubmed - Pubmed citation
- 7. Varga EA, Moll S. Cardiology patient pages. Prothrombin 20210 mutation (factor II mutation). Circulation. 2004;110 (3): e15-8. doi:10.1161/01.CIR.0000135582.53444.87 - Pubmed citation
- 8. María Canedo-Antelo, Sandra Baleato-González, Antonio J. Mosqueira, Jéssica Casas-Martínez, Laura Oleaga, Joan C. Vilanova, Antonio Luna-Alcalá, Roberto García-Figueiras. Radiologic Clues to Cerebral Venous Thrombosis. (2019) RadioGraphics. 39 (6): 1611-1628. doi:10.1148/rg.2019190015 - Pubmed
- 9. Mokin M, Ciambella CC, Masud MW, Levy EI, Snyder KV, Siddiqui AH. Whole-Brain Computed Tomographic Perfusion Imaging in Acute Cerebral Venous Sinus Thrombosis. (2016) Interventional neurology. 4 (3-4): 104-12. doi:10.1159/000442717 - Pubmed