Thrombosis of venous sinus

Cerebral venous sinus thrombosis (CVST) is the presence of a blood clot in the dural venous sinuses, which drain blood from the brain. Symptoms may include headache, abnormal vision, any of the symptoms of stroke such as weakness of the face and limbs on one side of the body, and seizures. [Source: Wikipedia ]

Venous sinus thrombosis
May Cause
Collateral cerebral circulation
Large vascular grooves of skull