Cerebrospinal fluid (CSF) is a clear, colourless fluid that surrounds the brain and spinal cord. It helps the brain by providing protection, nourishment and removing waste products. Its main role is to cushion the brain within the casing of the skull and act as a shock absorber for the central nervous system (CNS). CSF also helps support the weight of the brain. Nutrients needed by the brain are transported from the blood into the CSF. It also helps remove any waste products metabolised in the brain.
Changes to the cells, or the detection of cells which are not usually present, in CSF can be evidence of damage within the CNS. So, analysis of CSF can be used to help in the diagnosis of some conditions.
In MS, damage to the myelin sheath around nerves releases proteins into the CSF. These can be detected by analysing a sample of the fluid collected by a lumbar puncture. This test is sometimes used in the diagnosis of MS. If these proteins are found in the CSF but not in the blood, MS could be a possible cause.
