Diagnosing multiple sclerosis (MS) often requires several tests. One diagnostic test is known as a lumbar puncture (LP, or spinal tap). During a lumbar puncture, a needle is inserted in the lower back at the base of the spine to obtain a sample of cerebrospinal fluid (CSF). This sample is then taken to a lab and tested for a variety of substances, including different blood cell counts, protein and glucose levels, and antibodies.
Here is what you need to know about lumbar punctures and MS diagnosis, including what the test involves, how to prepare, and what the test’s results can tell your neurologist and health care team.
Cerebrospinal fluid (CSF) is a colorless fluid that surrounds the brain and spine. It serves as a cushion to the brain and a shock absorber to the central nervous system (CNS). CSF also removes waste products from the brain and helps circulate chemicals and nutrients from the blood.
In individuals with MS, the CSF obtained from a spinal tap likely contains higher-than-normal levels of proteins. This is due to demyelination, or damage to the protective coating (myelin sheath) surrounding nerves in the brain and spinal cord. The myelin damage responsible for MS symptoms causes certain proteins to be released into the CSF. High protein levels indicate immune system dysfunction, and the presence of a group of proteins called oligoclonal bands indicates MS.
It is important to note that a lumbar puncture alone cannot diagnose MS, as the spinal fluid of someone with the disease may not always be abnormal. And the immune response that produces proteins in CSF can be caused by a variety of other conditions, including lupus, human immunodeficiency virus (HIV), or even a stroke. In fact, 5 percent to 10 percent of those with a confirmed diagnosis of MS do not show any abnormalities in their lumbar punctures.
Several MyMSTeam members have described being diagnosed with MS despite first receiving negative spinal tap results. For many of them, magnetic resonance imaging (MRI) was required to visualize MS lesions on parts of their respective central nervous systems.
As one member wrote, they were diagnosed with MS after an MRI that was positive. “I had a lumbar puncture that was negative,” they posted. “My neurologist still says I have MS. I do have severe symptoms.” Other members described similar experiences. “I also had a spinal tap with a negative result, but an MRI that was positive. Just because your LP is negative does not mean you do not have MS,” one wrote. Another weighed in, adding, “My spinal tap was negative. But the MRI showed way too many lesions.”
A lumbar puncture is just one of the diagnostic tools that your health care team may use to evaluate whether you might have MS. Neurologists are also likely to perform physical and neurological exams, blood tests, and MRI tests to rule out other conditions and arrive at a definitive MS diagnosis.
A lumbar puncture usually takes about 45 minutes to complete. You will be asked to put on a hospital gown and lie down on your side with your legs pulled up to your chest. This position exposes the lower spine and separates the spinal bones to make inserting a needle easier. (Less frequently, you might be seated in an upright position and asked to bend forward.) A local anesthetic will be injected into the spinal cord area. For most people, this is the most painful part of the procedure.
After the area is fully numbed, a long, thin, hollow needle will be inserted into the back and the spinal cavity. There may be pressure as the spinal needle is inserted. If the needle touches a nerve in your spinal column, you may feel some sharp pain in your leg.
After the lumbar puncture is over, you will be asked to lie flat for an hour or more to minimize the chance of a so-called spinal headache. A spinal headache is a severe headache that can arise from the decreased pressure in your head that draining CSF causes. Although you can typically go home two hours after the procedure is over, you may be advised to have someone drive you home and avoid intense, tiring activity.
Headaches are a common side effect of lumbar punctures due to the decreased pressure around the brain that results from removing some CSF. The lost fluid will replace itself in around two days. In the meantime, staying hydrated, resting, and taking pain relievers (if recommended), can help with headache symptoms. “It took me a couple of days afterward to feel back to normal,” a MyMSTeam member reported.
Some people may worry that a lumbar puncture will be very painful. Several MyMSTeam members have shared their experiences to help others mentally prepare for the procedure. “It was not pleasant, but not as bad as I thought it would be,” one member said when another member prepped for the test. Another member reported how the procedure felt to them: “Just pressure and a slight pinch.” A third member recommended resting after the procedure. “A headache after is still possible, but avoidable, if you stay prone the rest of the day,” they wrote.
If you are currently on antibiotics or blood thinners, a lumbar puncture may not be an option. Tell your doctor about any medications you are taking or if there is a chance you might be pregnant.
In the two days leading up to your lumbar puncture, you should increase your fluid intake, unless you have a medical problem that does not permit you to do so safely. You should not eat anything for three hours before your procedure.
As a safety precaution, you will be unable to drive for 24 hours after a lumbar puncture. Some hospitals may require that you have a friend or family member escort you home after the procedure, even if you plan on taking a taxi or public transportation.
MyMSTeam members have offered a variety of tips for preparing for a lumbar puncture and recovering afterward.
Contact your doctor if you experience any of the following side effects after your lumbar puncture:
On MyMSTeam, the social network for people with multiple sclerosis and their loved ones,more than 185,000 members come together to ask questions, offer advice and support, and share their stories with others who understand life with MS.
Have you undergone a spinal tap during your diagnostic process? Share your experience in the comments below, or start a conversation by posting on MyMSTeam.