Lumbar Puncture Procedure Guide

Lumbar Puncture Procedure Guide
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A lumbar puncture, also referred to as a spinal tap, is a procedure performed in the lumbar area of the spine, or lower back. A lumbar puncture procedure is done to obtain a sample of cerebrospinal fluid in an attempt to diagnose or rule out medical conditions, or to confirm a diagnosis.

How to Prepare for a Lumbar Puncture

The patient will have a physical exam, blood work to look for clotting and bleeding disorders, and a medical history taken prior to this procedure. A CT scan is also sometimes necessary to look for abnormal swelling around or in the brain. Your past or current medications will also be reviewed.

How is a Lumbar Puncture Done?

  • The procedure will begin with the lower back being injected with a local anesthetic to numb the area. A hollow, thin needle is then

    inserted between two of the lumbar vertebrae and into the spinal canal (pressure is often felt during this).

  • The patients cerebrospinal fluid pressure is then measured, a little bit of it is collected, then the fluid pressure is again measured (still pressure during this for most patients).

  • If necessary, a substance or drug is injected.

  • The needle is then removed and the puncture site will be covered.

On average, a lumbar puncture takes about 45 minutes to an hour to complete, however, for some patients it will take longer.

Why is a Lumbar Puncture Done?

A lumbar puncture procedure is done for a number of reasons. In addition to collecting a sample of cerebrospinal fluid, this procedure may be done to:

  • Measure cerebrospinal fluid pressure
  • Inject radioactive substances or dyes into the cerebrospinal fluid to perform a diagnostic test known as myelography
  • Injecting chemotherapy drugs, anesthetics, or other medications

A lumbar puncture may be performed to help diagnose:

  • Subarachnoid hemorrhage (bleeding around the brain)
  • Certain nervous system inflammatory conditions, such as Guillain-Barre syndrome and multiple sclerosis
  • Certain cancers involving or associated with the spinal cord or brain
  • Serious fungal, bacterial, or viral infections, including encephalitis, meningitis, and syphilis

Possible Risks and Complications

This procedure is considered relatively safe, but there are still a few possible risks and complications that patients should be aware of. These include:

Back pain or discomfort: The lower back can be painful and tender after this procedure and the pain may go down the back of the patient’s legs.

Post-lumbar puncture headache: Approximately one in three patients will experience this. When spinal fluid leaks into the surrounding tissues, this headache can occur. They can last from a few hours to a few weeks and are sometimes accompanied by dizziness, vomiting, and nausea.

Bleeding: Patients taking anticoagulants, other blood thinners, or those who have clotting disorders are at risk for serious bleeding.

Brainstem herniation: The brainstem can become compressed after this procedure, specifically in those with pre-existing brain tumors, intracranial pressure increases, or lesions taking up space. However, this complication is not common.

Resources

Mayo Clinic. (2010). Lumbar Puncture (Spinal Tap). Retrieved on July 23, 2010 from the Mayo Clinic: https://www.mayoclinic.com/health/lumbar-puncture/MY00982

WebMD. (2008). Lumbar Puncture. Retrieved on July 23, 2010 from WebMD: https://www.webmd.com/brain/lumbar-puncture

Image Credits

Spinal Tap: Brainhell – Wikimedia Commons