Causes of Cerebral Venous Thrombosis
1. Trauma:
Even minor trauma of the head can easily damage some the superficial veins inside the skull and lead to thrombosis. Because the trauma is minor, the condition is often overlooked and the diagnosis is always delayed or missed. Other traumatic causes may include procedures to sample the fluid from the brain and infusions of drugs into the spinal cord.

2. Pregnancy and the immediate post partum period have both been linked to cerebral thrombosis.
Inflammatory bowel diseases: both Crohn's disease and ulcerative colitis have a tendency to cause cerebral blood clots in both the brain and elsewhere in the body. In addition, corticosteroids used to treat both these conditions have also been linked to the formation of blood clots in the cerebral veins.

3. Inherited blood disorders:
There are some individuals who have inherited medical disorders whereby they are prone to clot formation in the veins. These hypercoagulable conditions (antiphospholipid syndrome, protein S and C deficiencies, antithrombin III deficiency, lupus anticoagulant, and the Leiden factor V mutation) are not very common. In most cases, these conditions are suspected in an individual who develops recurrent and multiple clots all over the body. Pregnancy can sometimes be associated with a tendency to form clots in the blood vessels.

4. Infection:
Typically infections of the sinuses can extend into the brain and cause cerebral thrombosis. By causing an intense inflammatory reaction, the infection eventually causes thrombosis of the nearby veins. Infections of the frontal and mastoid sinuses are two most common causes of cerebral thrombosis.

5. Cancers:
Many individuals who develop cancers are also prone to development of blood clots in the veins. There are some conditions known as collagen vascular disorders (systemic lupus erythematosus, Wegener granulomatosis, and Beh?et syndrome) and these have occasionally been linked to the formation of cerebral thrombosis.

6. Idiopathic:
In some cases of cerebral thrombosis, no cause is found despite extensive investigation. This is simply bad luck.

7. Medical disorders:
Dehydration, renal and liver failure and also sometimes associated with formation of blood clots in the cerebral veins