Lumbar Puncture (Spinal Tap)
A lumbar puncture, also called a spinal tap, is a procedure in which the fluid surrounding the spinal cord (called the cerebrospinal fluid or CSF) is withdrawn through a needle and examined in a laboratory.
This procedure may be performed to:
- Measure the pressure around the brain and spinal cord
- Relieve pressure in the head
- Give spinal anesthesia
- Inject dye for an X-ray diagnostic test
- Inject medication (such as Baclofen)
Testing the CSF can help your doctor diagnose disorders of the central nervous system (including multiple sclerosis) that may involve the brain, spinal cord, or their coverings (meninges).
When the CSF is examined in the laboratory, the following are evaluated:
- The number and types of white blood cells
- The level of glucose
- The types and levels of proteins
- The presence of bacteria, fungi or abnormal cells
How do I prepare for the test?
- Maintain your regular eating schedule. There are no dietary or fluid restrictions before the test.
- Ask your doctor for specific guidelines about discontinuing , aspirin products, clopidogrel (Plavix®) or anticoagulant medications before the procedure.
- Tell your doctor if you are allergic to povidone-iodine (Betadine®) or procain (Novocain®).
- Please make arrangements for transportation, as you should not drive immediately after the test.
What happens during the test?
You will either lie on your side with your knees drawn as close to your chest as possible and your chin toward your chest, or sit with your arms and head resting on a table.
After cleaning your skin with an antiseptic, sterile cloths (called drapes) will be placed around the area. A local anesthetic (pain-relieving medication) will be injected into the area on your back. You may feel a slight burning sensation. When the area is numb, a hollow needle is inserted in the lower back between two lumbar vertebrae. This sometimes causes pressure. The spinal canal is penetrated, and fluid is collected or medication is injected. The spinal cord is not touched by the needle during the test.
You may feel some discomfort or have a minor headache.
The needle is removed after the medication has been injected or fluid has been removed. The area will be cleaned with an antiseptic and covered with a bandage.
You will lie on your back or stomach for about an hour.
A blood sample will be taken from a vein in your arm and tested, along with the spinal fluid, in the laboratory. NOTE: if the procedure was done to inject medication, a blood sample may not be taken.
Are there any risks or complications?
- Approximately 10% to 20% of people develop a spinal headache (one that worsens when sitting or standing).
- The risk of infection/epidural bleed is extremely low.
- Occasionally a small blood vessel is pierced, causing bloody discharge. No treatment is needed.
- The procedure is usually not painful, but momentary twinges of pain may be felt if the needle brushes against nervous tissue.
What should I do after the procedure?
- Avoid strenuous or vigorous exercise for a day or so after the procedure.
- If you have a headache, lie down as much as possible and drink plenty of caffeinated beverages.
- Drink 2 1/2 quarts of liquid the day of the test and the day after, even if you don't have a headache.
When should I call my doctor?
Call your local doctor immediately if you notice any unusual drainage, including bloody discharge, at the puncture site. You should also call immediately if you develop a fever or if your pain symptoms worsen.
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Lumbar Puncture (Spinal Tap)
Robbins E, Hauser SL. Chapter e46. Technique of Lumbar Puncture. In: Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 18e. New York, NY: McGraw-Hill; 2012.
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www.clevelandclinicflorida.org. This document was last reviewed on: 7/19/2014... index#12544