A lumbar puncture (also called a spinal tap) is a procedure to collect and look at the fluid (cerebrospinal fluid, or CSF) surrounding the brain and spinal cord.
During a lumbar puncture, a needle is carefully inserted into the spinal canal low in the back (lumbar area). Samples of CSF are collected. The samples are studied for color, blood cell counts, protein, glucose, and other substances. Some of the sample may be put into a container with a growth substance. This is called a culture. If any bacteria or fungi grow in the culture, an infection may be present. The pressure of the CSF also is measured during the procedure.
A lumbar puncture camera.gif is done to:
Find a cause for symptoms possibly caused by an infection (such as meningitis), inflammation, cancer, or bleeding in the area around the brain or spinal cord (such as subarachnoid hemorrhage).
Diagnose certain diseases of the brain and spinal cord, such as multiple sclerosis or Guillain-Barré syndrome.
Measure the pressure of cerebrospinal fluid (CSF) in the space surrounding the spinal cord. If the pressure is high, it may be causing certain symptoms.