brain, spinal cord, and nerve disorders
Overview of Brain Tumors
Diagnosis of Brain Tumors
Magnetic resonance imaging or computed tomography Sometimes a spinal tap A biopsy Doctors consider the possibility of a brain tumor in people who have had a seizure for the first time or who have characteristic symptoms. Although doctors can often detect brain dysfunction during an examination, other procedures are needed to diagnose a brain tumor. Magnetic resonance imaging (MRI) is the best test for identifying brain tumors. Computed tomography (CT) is a good alternative. It can identify most brain tumors. Before these tests, a substance that makes the tumor easier to see (a contrast agent for MRI or a radiopaque contrast agent for CT) is injected into a vein. These tests can show the tumor’s size and exact position in great detail. When a brain tumor is detected, more diagnostic procedures are done to determine the particular kind. Sometimes a Spinal Tap (lumbar puncture) is done to obtain cerebrospinal fluid for examination under a microscope. This procedure is done when doctors suspect that the tumor has invaded the layers of tissues that cover the brain (meninges). Such tumors may block the absorption of cerebrospinal fluid. A spinal tap may also help when the diagnosis or the type of tumor is unclear. Cerebrospinal fluid may contain cancer cells. However, a spinal tap cannot be done in people who have a large tumor that is increasing pressure within the skull. In these people, removing cerebrospinal fluid during a spinal tap may cause the tumor to move, resulting in Specialized tests can sometimes help with the diagnosis. For example, blood and cerebrospinal fluid may also be tested to check for substances secreted by tumors (called tumor markers) and for gene abnormalities that are characteristic of certain tumors. Identifying certain gene abnormalities can help predict which treatments will be most effective. A biopsy of the tumor (removal of a sample of the tumor for examination under a microscope) is done when results of MRI and other tests cannot definitively identify what the type of tumor is and whether or not it is cancerous. A biopsy may be done during surgery, in which all or part of the tumor is removed. Or if a tumor is difficult to reach, a stereotactic biopsy may be done. For this procedure, a frame is attached to the skull. The frame provides reference points that can be identified on an MRI or a CT scan. These reference points enable doctors to guide the biopsy needle precisely into the tumor. 