Before the needle is put, a local anesthetic is administered into your lower back to numb the puncture site. As the local anesthetic is administered, it will hurt slightly. You may feel dizzy or nauseated during the procedure. These symptoms will go away after the procedure. A spinal tap is any test that involves the removal of fluid from the spine. This can be done as a diagnostic tool for diseases such as multiple sclerosis, tuberculosis, and cancer. It can also be done to measure the pressure inside the skull when making decisions about treatment options for patients with brain tumors. In most cases, a spinal tap is performed as a routine part of your medical care by a doctor who specializes in neurology. However, this procedure does have some risks involved so it's important to discuss these with your doctor before you agree to have one done. The type of needle used to take the sample is called a "spinal needle." It is very thin and long (about an inch) with two parts: a small, blunt tip for making the skin contact and a larger, sharp point for removing fluid. The spinal needle is passed through the skin at the base of the neck, into the body, and down into the spine where the fluid can be removed.