Lumbar Puncture (cont.)
Kenneth Kaye, MD
Dr. Kaye received a Bachelor of Arts degree with honors from the University of California, San Diego in Applied Mechanics and Engineering Sciences. After graduating from New York Medical College, he completed his internship and residency training in pathology at Harbor - UCLA Medical Center.
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.
In this Article
- What is a lumbar puncture (LP)?
- Why is a lumbar puncture done?
- How is the LP performed?
- What is done next?
- What is the cerebrospinal fluid (CSF)?
- What is normal CSF?
- What diseases are diagnosed by examination of the CSF?
- What are the risks of an LP?
- What are the benefits of an LP?
An LP is most commonly peformed to diagnose a disease, namely to obtain a sample of the fluid in the spinal canal (the cerebrospinal fluid) for examination.
An LP 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 LP for the purpose of decreasing spinal fluid pressure in patients with uncommon conditions (such as, for examples, normal-pressure hydrocephalus and benign intracranial hypertension).
The patient is typically lying down sideways for the procedure. Less often, the procedure is performed while the patient is sitting up. LPs in infants are often done upright.
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 (CSF) removed for testing.
The CSF circulates around the brain and spinal cord (the central nervous system). This "water bath" acts as a support of buoyancy for the brain and spinal cord. The support of the CSF helps to protect the brain from injury.
The normal CSF contains various chemicals, such as protein and sugar (glucose), and few if any cells. The spinal fluid also has a normal pressure when first removed.
Next: What is normal CSF?
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