A lumbar puncture (LP), also known as a spinal tap, is a procedure used to access the cerebrospinal space to either obtain spinal fluid for testing or to infuse medication. The cerebrospinal space is the area surrounding the spine and brain, which contains cerebrospinal fluid. Cerebrospinal fluid (CSF) is a colorless fluid, produced in the ventricles of the brain, which acts as a buffer around the brain and spinal cord, to keep them safe from injury.
What is a lumbar puncture used for?
Lumbar punctures are necessary to both diagnose and treat some types of cancer. It can also be used to diagnose other medical conditions, including meningitis and multiple sclerosis. Cerebrospinal fluid, or CSF, can be removed and tested for cancer cells in a laboratory. Chemotherapy can be administered directly into the cerebrospinal space during a lumbar puncture to treat certain types of cancer.
How is the procedure done?
Prior to having an LP, you will have blood drawn to check your labs. You need a sufficient platelet count to ensure that your blood will clot at the site after the procedure. 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 that your spine is stretched out to create space between the bones in the back. Opening this space makes the cerebrospinal space more accessible. You will be instructed to either lie on your side in a fetal position in bed 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 in a comfortable position your provider will feel your back to determine the best place to insert the lumbar puncture needle. It is important to remain still during this time unless you are instructed to move. Once your provider has determined where to insert the needle, he or she will mark the spot with either a marker, a pen or with a piece of plastic making an indentation into the skin.
- Your doctor 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 ensure adequate numbness.
- A long, thin needle is then used to enter the cerebrospinal space through the location that was previously 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 notify your provider first. If you are feeling pain it is important to notify your provider. Once the needle is in the appropriate 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 typically takes about 15-30 minutes.
- Once the procedure is complete the needle is removed. A dressing is placed over where the needle was removed. You will then be instructed to lie flat, usually for 60 minutes. When you have 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 notify your care provider or nurse.
If you experience any other side effects, including dizziness, bleeding from the needle insertion site, blurry vision, uncontrolled nausea and vomiting or confusion, it is important to notify your provider immediately.
A lumbar puncture may be necessary to diagnose and treat your cancer. Like any aspect of your treatment, you should ask your provider to clarify any questions you may have.