The Lumbar Puncture Test

University of Iowa Department of Neurology
Peer Review Status: Internally Peer Reviewed
Creation Date: Unknown
Last Revision Date: Unknown (Edited for this website)

A Lumbar Puncture (Spinal Tap) Test drains a small sample of cerebral spinal fluid from the lower spine. A needle is inserted between the vertebrae (backbones) in the lower back and into the space containing the spinal fluid.

What is it?

• a procedure to remove a small sample of cerebral spinal fluid from the lower spine
• this fluid surrounds and cushions the brain and spinal cord

How long does it take?

• about 20 to 30 minutes
• there is a possible 2-hour recovery period after the test, which will take place in a suitable location

Why is the Lumbar Puncture test performed?

• to determine the spinal fluid pressure
• to obtain a specimen for testing (for either infection or bleeding)
• to relieve pressure around the brain by removing fluid
• to inject medications around the spinal cord

Does it hurt?

• you may experience pressure when the needle is inserted. You may also feel some fleeing leg pain while the needle is positioned because it may briefly touch a floating nerve ending.

What should you do to prepare for the test?

• eat normal meals
• if you are an outpatient, please bring a relative or friend who can drive you home
• continue taking prescribed medications unless your doctor gives other instructions

How is it performed?

• you will lie on your side with your knees drawn up toward your chin as far as possible
• the doctor will cleanse the skin over your spinal column with iodine
• an injection of local anesthetic is given at the puncture site
• a needle is inserted into your spinal fluid space
• Sometimes a long, thin tube called a manometer is attached to the needle to measure the fluid's pressure
• spinal fluid is collected into specimen tubes for laboratory testing

Frequently Asked Questions

• what if I'm unable to flex my back and legs?
  • the test can be done without bending or while sitting
• is the entire needle put into my back?
  • no, but the needle must be long enough to pass through the muscles of the lower back
• can I be paralyzed if the needle hits the spinal cord?
  • no, there is no need to worry about spinal cord damage. The needle is inserted well below the spinal cord.

After the test

• you will be asked to lie on your stomach for about 30 minutes or more
• after that, you will be asked to lie on your back or side for 2 or 3 hours (Neurologists vary with this requirement)
• report any of the following symptoms to the doctor or nurse:
  • headache
  • tingling
  • numbness or pain in your lower back and legs
  • problems with urination
• you may return to your hospital room or home, unless given other instructions from the doctor
• if you are being driven home, you should lie down in the vehicle, if possible
• you will learn the test results either from the doctor before you leave, or from a copy of the letter sent to your personal physician

Instructions to follow at home

• drink 8 to 12 glasses of fluid (no alcohol) in the next 12 hours, unless your doctor indicates otherwise
• remain quiet for the next 24 hours
• avoid any strenuous physical activity for 48 hours
• if you develope a headache, lie flat for the next 12 to 24 hours or until the headache goes away. Remember to drink plenty of fluids
• if your headache persists, call your home physician or the physician at the hospital who performed the Lumbar Puncture test.