A lumbar puncture (LP), also known as a spinal tap, is a procedure used to access the cerebrospinal space. The cerebrospinal space is the area surrounding the spine and brain, which contains cerebrospinal fluid (CSF). CSF is a colorless fluid made in the ventricles of the brain, which acts as a buffer around the brain and spinal cord to keep them safe from injury. Your provider may want access to your cerebrospinal space during an LP to either obtain spinal fluid for testing or to insert medication.
What is a lumbar puncture used for?
A lumbar puncture is needed to both diagnose and treat some types of cancer. Cerebrospinal fluid, or CSF, can be removed and tested for cancer cells. Chemotherapy can be given directly into the cerebrospinal space during a lumbar puncture to treat some types of cancer. An LP can also be used to diagnose other medical problems, including meningitis and multiple sclerosis (MS).
How is the procedure done?
Before having an LP, you will have blood drawn to check your labs. You need a certain platelet count to make sure that your blood will clot at the site after the LP. Your provider will also talk to you about medications or allergies you have that could affect the procedure.
- Your provider will position you in a way so that your spine is stretched out to create space between the bones in the back. Opening this space makes the cerebrospinal space easier to reach.
- You will be told to either lie on your side or you will sit on the edge of your bed and rest your chest, arms, and head on a tray or chair that has been placed in front of you, with your feet dangling off the bed.
- Once you are comfortable, your provider will feel your back to find the best place to insert the lumbar puncture needle. It is important to remain still during this time unless you are told to move. Once your provider has found where to insert the needle, the area will be marked with either a marker, a pen, or with a piece of plastic making an indent into the skin.
- Your provider will put on sterile gloves. The area is cleaned with a topical soap to prevent any germs from being introduced into the CSF. You will have a sterile drape placed on your back to cover the area not being affected by the lumbar puncture.
- Next, your provider will use a needle to give some anesthetic (numbing) medication in the area that the LP is being done. You may feel some burning or pressure for a few seconds before the numbing occurs. Your provider will touch the area and ask if you can feel it to make sure it is numb.
- A long, thin needle is used to enter the cerebrospinal space where it was marked and numbed. You may feel pressure, but you should not feel pain. It is important for you to stay as still as possible. If you need to move, you must ask your provider first. If you are feeling pain, tell your provider right away.
- Once the needle is in the right space, CSF is collected into test tubes. If you are receiving chemotherapy, it is then infused through this needle directly into the CSF. The whole procedure often takes about 15-30 minutes.
- Once the procedure is complete, the needle is removed. A dressing is placed where the needle was removed. You will then be told to lie flat, usually for 60 minutes. When CSF is removed and there is less CSF circulating than what is normal, it can cause a headache. Lying flat will prevent a headache while your body makes more CSF to replace what was removed. If you do have a headache, tell your provider.
If you have any other side effects, including dizziness, bleeding from the needle insertion site, blurry vision, nausea and/or vomiting that doesn’t get better, or confusion, it is important to tell your provider right away.
A lumbar puncture may be needed to diagnose and treat your cancer. Like any part of your treatment, you should ask your provider about any questions or concerns you may have.