Brain tumors are made up of cells that are growing abnormally in the brain. A brain tumor can be benign or malignant, and may have many symptoms: for example double vision, facial paralysis, unsteady walking, epileptic seizures, changes in personality, and unusual headaches or nausea. Since space inside the skull available for the brain is limited, even benign brain tumors can lead to serious symptoms because of the resulting pressure. On the other hand, someone can have a brain tumor and not have any symptoms for a long time.