Causes
Disorders that cause, or increase the risk for systemic venous thrombosis are associated with central venous thromboses. In children, head and neck infections and acute systemic illnesses are the primary cause of central venous thrombosis. Cerebral venous sinus thrombosis is more common in particular situations. 85% of people have at least one of these risk factors:
Thrombophilia, a tendency to develop blood clots due to abnormalities in coagulation, e.g. factor V Leiden, deficiency of protein C, protein S or antithrombin, or related problems
Nephrotic syndrome, a kidney problem causing protein loss in the urine
Chronic inflammatory diseases, such as inflammatory bowel disease, lupus and Behçets disease
Pregnancy and puerperium (the period after giving birth)
Particular blood disorders, especially polycythemia vera and paroxysmal nocturnal hemoglobinuria
Use of estrogen-containing forms of hormonal contraception
Meningitis and infections of the ear, nose and throat area such as mastoiditis and sinusitis
Direct injury to the venous sinuses
Medical procedures in the head and neck area
Obesity, especially in combination with oral contraceptive use 
Sickle cell anemia
Dehydration, primarily in infants and children
Homocysteinemia
Homocystinuria

Diagnosis
The diagnosis may be suspected on the basis of the symptoms, for example the combination of headache, signs of raised intracranial pressure and focal neurological abnormalities, or when alternative causes of headache and neurological abnormalities, such as a subarachnoid hemorrhage, have been excluded. Imaging
There are various neuroimaging investigations that may detect cerebral sinus thrombosis.
This, however, requires puncture of the femoral artery with a sheath and advancing a thin tube through the blood vessels to the brain where radiocontrast is injected before X-ray images are obtained. It is therefore only performed if all other tests give unclear results or when other treatments may be administered during the same procedure. D-dimer
There is an association between the D-dimer blood test and cerebral venous sinus thrombosis. This association however is not strong enough to rule out the diagnosis alone. Further tests
In most cases, the direct cause for the cerebral sinus thrombosis is not readily apparent. Identifying a source of infection is crucial; it is common practice to screen for various forms of thrombophilia (a propensity to form blood clots). Pathogenesis
The veins of the brain, both the superficial veins and the deep venous system, empty into the dural venous sinuses, which carry blood back to the jugular vein and thence to the heart. In cerebral venous thrombosis, blood clots usually form both in the veins of the brain and the venous sinuses. The thrombosis of the veins themselves causes venous infarction (damage to brain tissue due to a congested and therefore insufficient blood supply). This results in cerebral edema (both vasogenic and cytotoxic edema), and leads to small petechial haemorrhages that may merge into large haematomas. Thrombosis of the sinuses is the main mechanism behind the increase in intracranial pressure due to decreased resorption of cerebrospinal fluid (CSF).