A lumbar puncture, also known as a spinal tap, is a test to evaluate the fluid (cerebrospinal fluid) surrounding the brain and spinal cord. This is done by inserting a needle into the lumbar (small of the back) portion of the back. Franklin Moser, MD, Chief of Neuroradiology, heads our team of imaging physicians, nurses and echnologists who specialize in this procedure.
A lumbar puncture is most commonly peformed to diagnose a disease. It can also be done to treat diseases. For example, as a way of administering antibiotics, cancer drugs, or anesthetic agents into the spinal canal. Spinal fluid is sometimes removed by lumbar puncture for the purpose of decreasing spinal fluid pressure in patients with uncommon conditions.
The patient is typically lying down sideways for the procedure. Less often, the procedure is performed while the patient is sitting up.
After local anesthesia is injected into the small of the back (the lumbar area), a needle is inserted in between the nearby bony building blocks (vertebrae)into the spinal canal. (The needle is usually placed between the 3rd and 4th lumbar (vertebrae).
Spinal fluid pressure can then be measured and cerebrospinal fluid removed for testing.