Lumbar Puncture

A lumbar puncture is a short procedure sometimes used to help diagnose MS. It is also called a spinal tap.

What is a lumbar puncture?

A lumbar puncture can be done inside or outside of the hospital. It involves inserting a needle through the back and into the spinal column. The spinal column is the space around the spinal cord. A small sample of cerebrospinal fluid (CSF) is collected. CSF is a colorless fluid produced in the brain. It surrounds the brain and spinal cord to provide cushioning and important nutrients.1,2

What is a lumbar puncture used for?

Studying the contents of a person’s CSF in a lab can be very helpful in diagnosing a variety of neurological conditions or infections. The amount of glucose (sugar), proteins, blood, bacteria, white blood cells, and more in the CSF can be measured.

Different conditions have different spinal fluid characteristics. For example, if a person’s spinal fluid is orange or red, they may have a bleed in the brain. If the CSF has many white cells, an infection may be present. The pressure of spinal cord fluid can also be taken to determine the pressure in a person’s brain (intracranial pressure).

A lumbar puncture may also be used to deliver medicine both inside and outside the spinal cord. This includes numbing drugs during childbirth (epidural anesthesia) and certain types of chemotherapy.1-3

Lumbar puncture and MS

Lumbar punctures are not always needed to diagnose MS. But they can be helpful when the diagnosis of MS is less clear. A specific type of protein called oligoclonal bands (O-bands) is often found in the CSF of people with MS.

According to the most recent McDonald criteria for MS, O-bands can be used as an additional diagnostic tool when a person has not yet had multiple attacks of MS-like symptoms but is developing MS.3-5

What to expect during a lumbar puncture

The whole process of a lumbar puncture may take anywhere from 15 minutes to an hour. Although inserting a needle into the back can be painful, a patient is typically not sedated. Instead, they are given local numbing drugs through a smaller needle before the actual procedure. Before the procedure, the lower back is cleaned with a special soap to reduce the risk of infection.

The needle is inserted between 2 vertebrae in the lower back (the lumbar spine). The patient is usually in a sitting position, leaning over a hard surface, or laying on their side with their knees pulled into their chest. Bending the spine like this gives your doctor a bigger space between vertebrae to insert the needle.

Once the needle is in, your doctor will take small samples of fluid to send to a lab. Afterwards, the needle is removed and a bandage is placed on the site. You will need a ride home after the procedure. Driving is not recommended immediately after a spinal tap. Most people relax for the rest of the day after a lumbar puncture but are able to go back to their regular lives soon after.1,2

Risks of a lumbar puncture

It is not uncommon to have pain at the procedure site after a spinal tap. Most over-the-counter pain relievers can help. As many as 1 in 4 people have a headache after a spinal tap. This headache starts within a day or 2 of the procedure and does not respond to regular pain medications. The best way to reduce the pain from a post-spinal tap headache is to lay flat. These headaches typically go away within a few days.

There are some very rare but serious side effects of a lumbar puncture. One is bleeding at the injection site or into the space around the spinal cord. Tell your doctor about any blood-thinning or anti-blood-clotting drugs you take before the procedure. These can increase the risk of bleeding.

Another very rare side effect of a lumbar puncture is brain herniation. If a person has increased pressure in their skull or a brain mass, it is possible for the base of the brain to be compressed during the procedure. Thankfully, most people receiving a spinal tap do not have brain masses or increased pressure in the skull. If there is any concern, your doctor will order brain imaging before performing the procedure.1,2

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Written by: Casey Hribar | Last reviewed: June 2021.