Lumbar Puncture

A lumbar puncture (also called a spinal tap) is a procedure to collect and look at the fluid (cerebrospinal fluid, or CSF) surrounding the brain and spinal cord.

During a lumbar puncture, a needle is carefully inserted into the spinal canal low in the back (lumbar area). Samples of CSF are collected. The samples are studied for color, blood cell counts, protein, glucose and other substances. Some of the sample may be put into a special culture cup to see if any infection, such as bacteria or fungi, grows. The pressure of the CSF also is measured during the procedure.

Why It Is Done

A lumbar puncture is done to:

• Find a cause for symptoms possibly caused by an infection (such as meningitis), inflammation, cancer or bleeding in the area around the brain or spinal cord (such as subarachnoid hemorrhage).
• Diagnose certain diseases of the brain and spinal cord, such as multiple sclerosis or Guillain-Barré syndrome.
• Measure the pressure of cerebrospinal fluid (CSF) in the space surrounding the spinal cord. If the pressure is high, it may be causing certain symptoms. 

In rare cases, a lumbar puncture may be used to lower the pressure in the brain caused by too much CSF.

How To Prepare

Before you have a lumbar puncture, tell your doctor if you:

• Are allergic to any medicines, such as those used to numb the skin (anesthetics).
• Have had bleeding problems or take blood-thinners, such as aspirin or warfarin (Coumadin).
• Are or might be pregnant.
• Take any herbal remedies. Some of these remedies may thin the blood.

You should try to empty your bladder before the procedure.

For a lumbar puncture, you will be asked to sign a consent form. Talk to your doctor about any concerns you have regarding the need for the procedure, its risks, how it will be done, or what the results will mean.

Spinal Headache

A post spinal tap headache can occur in approximately one third of patients after a lumbar puncture. Women are more susceptible to getting them. The chance of it occurring may be lessened by using a smaller gauge needle. Typically doctors will have patients lie flat after the procedure for 20 to 30 minutes.

Post spinal headaches are diagnosed if a patient has a headache that is present when standing up but goes away as soon as they lie down. Usually this headache will go away in about 24 hours. Bed rest, analgesics, hydration and caffeine can help. If the headache persists, your doctor may want you to have a blood patch, which is a procedure done typically by an anesthesiologist where some of your blood is drawn and injected back into the epidural space forming a seal over the site of the lumbar puncture which usually is very effective at improving a spinal headache.