Lumbar Puncture (LP or Spinal Tap)

  • Medical Author:
    Jerry R. Balentine, DO, FACEP

    Dr. Balentine received his undergraduate degree from McDaniel College in Westminster, Maryland. He attended medical school at the Philadelphia College of Osteopathic Medicine graduating in1983. He completed his internship at St. Joseph's Hospital in Philadelphia and his Emergency Medicine residency at Lincoln Medical and Mental Health Center in the Bronx, where he served as chief resident.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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What is normal CSF?

Normal values for spinal fluid examination are as follows:

  • Protein (15-45 mg/dl)
  • Glucose (50-75 mg/dl)
  • Cell count (0-5 mononuclear cells)
  • Initial pressure (70-180 mm)

These normal values can be altered by injury or disease of the brain, spinal cord, or adjacent tissues. The values are routinely evaluated during examination of the spinal fluid obtained from the lumbar puncture. Additionally, spinal fluid is tested for infection in the microbiology laboratory.

A health-care provider will usually review and interpret the test results with the patient. These results often will need to be evaluated in relation to other blood and radiologic test results.

What diseases are diagnosed by examination of the CSF?

Spinal fluid obtained from the lumbar puncture can be used to diagnose many important diseases such as bleeding around the brain; increased pressure from hydrocephalus; inflammation of the brain, spinal cord, or adjacent tissues (encephalitis, meningitis); tumors of the brain or spinal cord, etc. Sometimes spinal fluid can indicate diseases of the immune system, such as multiple sclerosis.

What are possible risks, complications, or side effects of a lumbar puncture?

When spinal fluid is removed during an LP, the risks include headache, brain herniation, bleeding, and infection. Each of these complications are uncommon with the exception of headache, which can appear from hours to up to a day after a lumbar puncture. Up to 25 % of patients will get headaches after the procedure. Headaches occur less frequently when the patient remains lying flat several hours after the procedure.

What are the benefits of a lumbar puncture?

The benefits of the LP depend upon the exact situation for which it is performed, but a lumbar puncture can provide lifesaving information.

REFERENCE:

Longo, D.L., et al. Harrison's Principles of Internal Medicine, 18th ed. New York: McGraw-Hill Professional, 2011.

Medically Reviewed by a Doctor on 11/2/2015
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