Lumbar puncture test

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 a lumbar puncture test?

This test is a procedure that removes a small sample of cerebral spinal fluid from the lower spine. This fluid surrounds and cushions the brain and spinal cord.

How long does a lumbar puncture test take?

Each test takes about 20 to 30 minutes. There is a possible two-hour recovery period after the test, which will take place at the Neurology Clinic.

Why is the lumbar puncture test performed?

There are several reasons your doctor may recommend this test:

• 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 getting a lumbar puncture test hurt?

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

Where is it conducted?

At University of Iowa Hospitals & Clinics, the lumbar puncture tests are conducted in the treatment rooms of the Neurology Clinic.

How many lumbar puncture tests are conducted each year?

Several hundred tests are conducted each year for various reasons.

What should you do to prepare for the lumbar puncture 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 a lumbar puncture test performed?

1. You will lie on your side, with your knees drawn up toward your chin as far as possible.
2. The doctor will cleanse the skin over your spinal column with iodine.
3. An injection of local anesthetic may be given at the puncture site.
4. A needle is inserted into your spinal fluid space.
5. A long, thin tube called a manometer is attached to the needle to measure the fluid's pressure.
6. Spinal fluid is collected into specimen tubes for laboratory testing.

Frequently asked questions about lumbar puncture tests

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 a Lumbar Puncture Test

• You will be asked to lie on your stomach for about 30 minutes.
• After that, you will be asked to lie on your back or side for 15 to 90 minutes.
• Your nurse will check the puncture site periodically for swelling or leakage of spinal fluid. They will also ask you to wiggle your toes and move your legs.
• 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 your doctor.
• If you are being driven home, you should lie down in the vehicle, if possible.
• You will learn the test results either from your doctor before you leave, or from a copy of the letter sent to your personal physician.

Instructions to follow at home after a lumbar puncture test

• Drink eight to 12 glasses of non-alcoholic fluid 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 develop 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 physician.