Making the Diagnosis
Based on the above symptoms, your doctor may suspect brain cancer. The first step in correctly diagnosing any type of brain cancer is to undergo a computerized tomography (CT) or magnetic resonance imaging (MRI) scan. These specialized scans can detect many types of brain tumors and determine their exact location and size. However, they can't tell if the tumor is cancerous or not.
A biopsy must be done to find out whether the tumor is cancerous. In order to do this, a piece of the tumor is removed during surgery. If the tumor is too deep inside the brain, surgeons can use a technique called stereotactic biopsy or three-dimensional needle placement. An MRI scan is used to create a 3-D image of the brain which is then used to guide a needle held in a special frame to the proper spot in the brain. tumor cells are then drawn into the needle and collected for examination. After the biopsy sample is removed, it is analyzed using microscopes and special chemicals to determine the type of tumor. It usually takes a few days to get the results of a biopsy.
Brain tumor cells can sometimes be drawn from the cerebrospinal fluid (CSF), which is a special fluid that surrounds the brain and spinal cord. The CSF is drawn out through a thin needle inserted in the lower back under local anesthetic - this is called a lumbar puncture. This procedure can't be done if there's any build-up of pressure in the brain. The change in brain pressure caused by a puncture could suck some of the brain tissue down into the base of the skull, causing serious complications.