Lumbar Puncture (Spinal Tap)
Lumbar puncture or spinal tap is done by obtaining a sample of cerebrospinal fluid by inserting a needle in your lower back.
This procedure is performed to diagnose meningitis, encephalitis, bleeding around the brain, multiple sclerosis, cancers of the brain and/or spinal cord, and related concerns of the central nervous system. A lumbar puncture may also be done to inject medications (such as chemotherapy drugs and anesthesia) and dye (needed in diagnostic images).
For instance, a patient who underwent the procedure was asked not to eat or drink anything after midnight. The next morning, his back was washed and covered with a sterile sheet; he was then asked to lie down on his side with his knees drawn up to his chest. A local anesthetic was first injected which was followed by the insertion of a hollow needle between his two lower vertebrae. After measuring the cerebrospinal fluid pressure, a small amount was withdrawn and the pressure was remeasured. The needle was removed and the puncture area was bandaged. The obtained sample was then sent to the laboratory. The whole procedure lasted for about 45 minutes.