Cerebral vein thrombosis refers to the formation of a blood clot in intracranial veins. This condition comprises cortical vein thrombosis, dural vein thrombosis and venous sinus thrombosis.
Clinical presentation of CVT patients largely depends on location and extent of thrombosis and possibly hemorrhagic infarction. Furthermore, symptom onset may be acute (< 48 hours; 37%), subacute (> 48 hours but < 30 days; 56%) or chronic (> 30 days; 7%) .
Diagnostic imaging is applied to confirm a tentative diagnosis of CVT, to locate the thrombus (or thrombi) and to assess brain damage. Magnetic resonance flow imaging and contrast-enhanced computed tomography scans are most commonly carried out to this end, with the former being more sensitive than the latter. As time elapses after thrombus formation, findings vary :
It is of utmost importance to determine whether a CVT patient is suffering from any systemic prothrombotic condition since such disorders also favor thrombus formation within other vessels. Consequently, affected individuals present increased risks of ischemic stroke, myocardial or renal infarction, and other thrombosis-related diseases. A screen for systemic hypercoagulability may comprise laboratory analysis of blood samples (hemogram, blood biochemistry and coagulation tests), diagnostic imaging (applying those techniques described for diagnosis of CVT itself) and genetic testing .
If no risk factor can be identified, repeated analysis after a few weeks is recommended. Certain malignancies, for instance, may cause hypercoagulability. If they are not detected during initial exams but during follow-ups, treatment may still be initialized in a timely manner.
Of note, recovery (principally recanalization and development of collaterals) and possible recurrence should also be monitored in follow-ups, ideally by means of magnetic resonance imaging.
Thrombolysis is the mainstay of CVT treatment. For a long time, it has been a matter of debate whether patients who are presenting with intracranial hemorrhage due to CVT should receive heparin and/or fibrinolytics. This therapeutic approach continues to rise significant concern, but available data emphasize the importance of an early thrombolytic therapy in all patients . As has been mentioned above, mortality is significantly higher in those patients who do not receive thrombolytic therapy .
Chemical and/or mechanical thrombectomy should be considered in patients who deteriorate under standard therapy or who are moribund on presentation . These patients should nevertheless receive anticoagulants.
Additionally, supportive measures may be provided to relieve symptoms associated with CVT. For instance, patients who suffer from seizures may benefit from anti-epileptic drugs like sodium valproate or phenytoin. Benzodiazepines are generally administered to terminate status epilepticus .
Availability, sensitivity and specificity of modern imaging techniques have significantly decreased CVT-associated mortality. A large retrospective study based on data obtained in more than 600 cases diagnosed in nearly two dozen countries yielded the following results: about 80% of all CVT patients recovered completely, 10% remained mild to moderately disabled, 2% remained severely disabled and 8% died .
Early initiation of thrombolytic therapy considerably improves the outcome and if thrombolysis is not carried out, mortality rises to more than 60% . Unfavorable prognostic parameters are decreased awareness, cerebral hemorrhages, status epilepticus and paralysis. These symptoms are often associated with hemorrhagic infarctions visible in images obtained by magnetic resonance imaging or computed tomography scans..
With regards to congenital diseases, a variety of genetic disorders may cause a systemic prothrombotic condition. Prothrombin G20210A and factor V Leiden mutation as well as deficiencies in protein C, protein S or antithrombin III shall be mentioned as examples for hereditary diseases associated with an increased risk of CVT  . Mutations of the gene encoding for methylenetetrahydrofolate reductase have also been proposed as possible triggers of CVT . Such mutations are commonly associated with thrombosis.
More commonly, CVT is caused by acquired disturbances of hemostasis. Such disorders may provoke thrombi formation in distinct vessels of the whole body or be restricted to determined intracranial areas. Dehydration, use of oral contraceptives, pregnancy and puerperium as well as antiphospholipid syndrome and hypercoagulability due to malignancies are related to an overall increased risk of vein thrombosis. This also applies for pathologies causing polycythemia or thrombocytosis. Head trauma, intracranial neoplasms or inflammatory processes affecting either the brain itself or adjacent tissues are possible local causes of CVT. Malignant otitis media, mastoiditis and sinusitis may compromise cerebral veins; although inflammation is less identified as the cause of CVT.
In the majority of cases, at least one of the aforementioned risk factors is identified in patients presenting with CVT. This particularly applies to pediatric patients and young adults. In the elderly, the proportion of cases that cannot be ascribed to any underlying disease is more prominent.
In general, CVT is an uncommon disease. It is also a rare cause of cerebral infarction. The annual incidence of CVT has been repeatedly estimated to be less than 1 per 100,000 inhabitants. Incidence rates don't seem to vary among different age groups, but the likelihood of suffering CVT is significantly increased in patients pertaining to the above mentioned risk groups. Pregnancy, for instance, causes a 10-fold increase in the risk of CVT.
In general, most patients are diagnosed with CVT during their fourth and fifth decade of life, but young children account for considerable shares of CVT patients too.
Women are affected three times more often than men . Pregnancy, puerperium and the use of oral contraceptives have been identified as gender-specific risk factors and may partially explain the observed female predilection, which is less marked in children and elder women than in young adults. Women tend to suffer from CVT at younger ages and have a better prognosis than men.
Endothelial lesions, blood stasis and alterations of blood composition - commonly known as Virchow's triad - are the main triggers of thrombosis and CVT is no exception to this rule . As indicated in the Etiology section of this article, many conditions may evoke one of those states and since they are mutually dependent, this may lead into a self-perpetuating cycle. Endothelial lesions, for instance, may result from local inflammatory processes. They cause formation of white thrombi, i.e., of blood clots that mainly consist of thrombocytes. However, local disturbances of blood flow cause blood stasis and formation of secondary red thrombi. Consequently, the thrombus grows and blood drainage decreases further.
Reduction of venous drainage due to CVT causes cerebral blood flow to decrease. Those brain regions that are drained by the affected vessel are not supplied with oxygen and nutrients; the patient sustains cerebral infarction. Because vessels passing through the infarct core are filled with blood, CVT triggers hemorrhagic infarction not ischemic stroke. Pathophysiological events following infarction and blood-brain barrier breakdown are neuronal death, cytotoxic and vasogenic edema, hemorrhages, hematoma, microgliosis and astrogliosis. Persistent neuroinflammation may significantly contribute to CVT-associated morbidity and mortality.
Additionally, thrombi may exert a local mass effect and compress adjacent tissues. Cavernous sinus syndrome, for instance, is associated with neurological symptoms due to compression of the oculomotor, trochlear, trigeminal and/or abducens nerves (cranial nerves III, IV, V and VI, respectively). It is caused by space-occupying processes taking place in the cavernous sinus - by CVT, for instance .
Appropriate hydration is an important preventive measure against CVT. This applies particularly to patients pertaining to any of the above described risk groups, e.g., pregnant women, women who take oral contraceptives, anyone suffering from a systemic illness or a disease affecting the head and neck region.
Patients diagnosed with inherited thrombophilia should receive prophylactic treatment against CVT.
Cerebral vein thrombosis (CVT) refers to the formation of a blood clot in intracranial veins and most commonly, this condition affects more than one vessel.
Of note, physicians often use the term cerebral thrombosis in a broader sense and may not only refer to thrombus formation within a cerebral vessel, but also to vessel occlusion due to thromboembolism. The former more frequently occurs in veins and vein sinus and is the topic of this article. Emboli, in contrast, tend to lodge in arteries. They block arterial blood supply to dependent tissues and cause ischemic infarction. Thromboembolism is the most common cause of stroke and incidence rates are much higher than those of CVT.
Thrombus formation may be triggered by a variety of local and systemic diseases that provoke endothelial damage or that interfere with the equilibrium between pro- and anticoagulatory factors. And although small thrombi may not significantly diminish blood drainage, they do constitute obstacles that alter fluid mechanics locally. This contributes to the formation of secondary red thrombi and further reduction of venous outflow. In severe cases, the affected vein or vein sinus may become occluded.
The above described events may lead to hemorrhagic infarction of the area drained by the affected vessel and trigger symptoms of stroke. Contrary to thromboembolic stroke, symptom onset is not necessarily acute. Indeed, subacute or chronic onset of symptoms is observed in two out of three patients presenting with CVT . Clinical presentation varies largely and complaints range from headaches, visual impairment and dysarthria to hemiparesis and coma.
CVT is diagnosed by means of neuroimaging and treatment generally consists of thrombolysis.
Cerebral vein thrombosis (CVT) is the medical term for the formation of a blood clot within an intracranial vein. Thrombi may interfere with blood drainage, cause an increase in venular, capillary and finally arterial blood pressure and thus reduce cerebral blood flow. This may lead to hemorrhagic infarction and stroke.
Of note, CVT is an uncommon trigger of stroke. Most cases of cerebral infarction are provoked by thromboembolism, i.e., blood clots form within any vessel and are carried away into cerebral arteries.
Any condition provoking endothelial damage or blood stasis in cerebral vessels as well as pathologies that incline the balance between coagulation and fibrinolysis towards the former may cause CVT. The following shall be mentioned as examples:
The most common symptom of CVT are headaches. Symptom onset may be acute, subacute or chronic and patients may claim headaches to intensify within hours, days or weeks. Possibly, headaches aggravate when adopting certain postures.
Further symptoms of CVT are:
In order to confirm a tentative diagnosis of CVT, magnetic resonance imaging or computed tomography scans will be applied. By means of these techniques, the affected vein and the thrombus lodged within it can be visualized. They also allow for an evaluation of concomitant brain damage.
As has been indicated above, CVT may be triggered by a variety of conditions. Laboratory analyses of blood samples and genetic tests may be carried out to identify the cause of CVT in an individual case.
In most cases, drug-mediated thrombolysis is indicated. Patients receive heparin and/or fibrinolytics that dissolve the thrombus and facilitate recanalization. In severe cases, surgery may be necessary to mechanically remove the blood clot.