What to Expect From a Spinal Tap

And How to Prepare

A demonstration of the spinal tap technique.
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A spinal tap, also referred to as a lumbar puncture, is a procedure performed by your healthcare provider in order to collect and study the clear fluid, or cerebrospinal fluid, that surrounds the brain and spinal cord.

Why You Might Need a Spinal Tap

This procedure is sometimes necessary to help your healthcare provider determine the cause of your ​seizures, like whether you have an infection, inflammatory process, or certain cancer of the brain and spinal cord.

A spinal tap can also be used to treat certain health conditions. For example, a spinal tap can be utilized to give antibiotics, anti-cancer drugs, and anesthetics. If can also be used to remove cerebrospinal fluid, which can temporarily help people with ​idiopathic intracranial hypertension — a headache disorder that originates from increased spinal fluid pressure.


Preparing for a spinal tap is fairly easy. Before this procedure, your healthcare provider will ask you about your medical history, including questions regarding your medication history (including herbal and other natural remedies), allergies, and other conditions, such as a bleeding disorder or pregnancy status.

The Procedure

A spinal tap is usually performed in the emergency room, in the hospital at your bedside, or in a clinic room of your neurologist's office. During the procedure, you will lie on the bed on your side, with your knees bent close to your chest, similar to a fetal position. You may also be asked to sit at the edge of your bed with your lower back pushed out, like in a hunchback position.

Your doctor will clean and sterilize your lower back — called the lumbar area — thoroughly in order to prevent an infection at the injection site. A numbing medication, usually lidocaine, is injected into the skin around the needle insertion so that you won't feel much discomfort, mainly just some pressure. Next, a long, sterile needle is inserted between two vertebrae and into the spinal canal — a space or tunnel through which the spinal cord runs and where the cerebrospinal fluid is present.

Once the needle is in the spinal canal, the fluid will flow out and be collected for further analysis. Normal cerebrospinal fluid should be clear and contain protein, glucose, a few cells and a normal pressure.

What to Expect

You may experience some soreness at the site for the next day. Headache is the most common complaint of a spinal tap and can occur within 48 hours after the procedure. The headache is due to small amounts of cerebrospinal fluid leaking out of the site in your back where the needle was inserted. It usually feels better with lying down, fluids, and caffeine. Less commonly, a blood patch is needed to close up the puncture site, if the headache persists.


The good news is that complications are usually minimal. However, if for any reason you develop fever, chills, headache, stiff neck, drainage or bleeding from the site of the spinal tap, or weakness, tingling or numbness below the puncture site, notify your healthcare provider immediately.

View Article Sources
  • Ellenby MS, Tegtmeyer K, Lai S et al. Lumbar Puncture. N Engl J Med 2006; 355:e12.