A spinal tap (also called lumbar puncture) removes fluid from the spine. This fluid is called cerebrospinal fluid and in Multiple Sclerosis this fluid is examined to see if there in an increase in gamma globulin formation. An increase in gamma globulin is a sign of Multiple Sclerosis. Gamma globulin is a protein that works with the body’s immune system to help fight infections. This procedure takes about 20 minutes. The patient lies down on their side with their knees up near their chest. The lower part of the spine, where a needle will go in to withdraw the cerebrospinal fluid, is numbed with a local anesthetic. After the needle is taken out, the site where the needle was is covered up. A common side effect of this test is a mild headache.
Additional resources that provide more information on spinal taps: