Diagnosing multiple sclerosis (MS) often requires several tests. One diagnostic test is known as a lumbar puncture (LP, or spinal tap). In this procedure, a thin needle is carefully inserted into the lower back to collect a sample of cerebrospinal fluid (CSF). The fluid is then tested in a lab for signs of MS, such as specific proteins and immune system activity.

You may be wondering, “Can you have MS with a negative spinal tap?” Here’s what you need to know about lumbar punctures and MS diagnosis, including what the test involves, how to prepare, and what the results can tell your neurologist and healthcare team.

How Can a Lumbar Puncture Help Diagnose MS?

Cerebrospinal fluid is a colorless fluid that surrounds the brain and spinal cord. It serves as a cushion for 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.

What Spinal Tap Results Indicate MS?

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 myelin sheath (protective coating) 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 IgG bands can indicate MS.

Can You Have MS With Normal Cerebrospinal Fluid?

A lumbar puncture alone can’t diagnose MS, because the spinal fluid of someone with the disease may not always be abnormal. Also, the immune response that produces proteins in CSF can be caused by other conditions, such as infections or inflammatory conditions. In fact, 5 percent to 10 percent of those with a confirmed diagnosis of MS don’t show any abnormalities in their lumbar punctures.

Do You Need a Spinal Tap To Diagnose MS?

A lumbar puncture isn’t always needed to diagnose MS if your symptoms and MRI results clearly indicate the disease. However, it can help in certain cases, such as when symptoms suggest MS but MRI results are unclear or show few or no lesions (areas of damage in the brain or spinal cord caused by inflammation). This test is also useful for unusual cases, such as when symptoms are progressive from the start or when diagnosing children and older adults.

What Does It Mean if My Spinal Tap Results Are Negative?

Several MyMSTeam members described having been 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 central nervous system.

One member wrote about being diagnosed with MS after a positive MRI test result: “I had a lumbar puncture that was negative. 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 member added, “My spinal tap was negative. But the MRI showed way too many lesions.”

A lumbar puncture is just one of several tests your healthcare team may use to help determine if you have MS. Diagnosis typically involves a thorough medical history, physical and neurological exams, blood tests, and MRI scans to rule out other conditions.

What To Expect During a Spinal Tap for MS

The entire process of a lumbar puncture usually takes about 45 minutes. Most often, you’ll lie on your left side with your legs pulled up to your chest. This position exposes the lower spine and helps open the space between the spinal bones for the needle. In some cases, you might sit and lean forward instead. A local anesthetic will be injected to numb the area, which is typically the most painful part of the procedure.

After the area is fully numbed, a long, thin, hollow needle will be inserted into your lower back and spinal cavity. You may feel some pressure as the spinal needle is inserted. If the needle touches a nerve in your spinal column, you may feel a sharp pain in your leg.

After the lumbar puncture, you’ll need to lie flat for at least an hour to help reduce the risk of developing a spinal headache. This headache is a common side effect when cerebrospinal fluid is drained, temporarily lowering pressure in your head. Most people can go home about two hours after the procedure, but it’s a good idea to avoid intense, tiring activity.

If you get a spinal headache, the lost fluid will replenish itself in around two days. In the meantime, staying hydrated, resting, and taking pain relievers (if recommended), can help ease headache symptoms. “It took me a couple of days afterward to feel back to normal,” a MyMSTeam member reported.

Is a Spinal Tap for MS Painful?

Lumbar punctures can cause discomfort, but some people find them painful. Several MyMSTeam members have shared their experiences to help others mentally prepare for the procedure. They posted comments such as these:

• “It was not pleasant, but not as bad as I thought it would be.”
• “Just pressure and a slight pinch.”
• “A headache after is still possible, but avoidable, if you stay prone the rest of the day.”

If you’re taking 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.

How To Prepare for a Lumbar Puncture

In the two days leading up to your lumbar puncture, you should drink more fluids, unless you have a medical problem that prevents you from doing so safely. Avoid eating anything for three hours before your procedure.

As a safety precaution, you may be advised not to drive for 24 hours after a lumbar puncture. Some hospitals may require that you have a friend or family member escort you home afterward, even if you plan on taking a taxi or public transportation. Your doctor will explain the risks and benefits of the procedure and what to watch for afterward.

MyMSTeam members have offered a variety of tips for preparing for a lumbar puncture and recovering afterward.

• “The key to getting through a lumbar puncture is to RELAX!”
• “I recommend you NOT move while getting it. Afterward, I felt sleepy for hours, but I was in the hospital anyway.”
• “Lie flat the remainder of the day so the puncture hole can heal. Hydrate the day before and after.”
• “You have to stay down in bed until 24 hours have passed. Other than that, there is nothing to it.”
• “Be sure to follow the aftercare instructions fully.”
• “Rest as much as possible and lie down.”

After Your Lumbar Puncture

Contact your doctor if you experience any of the following side effects after your lumbar puncture:

• Severe headache lasting more than a few hours
• Mild headache lasting more than a week
• Tingling or numbness in the legs or lower back
• Inability to urinate
• Swelling, bleeding, or significant pain at the puncture site
• Fever or chills and a stiff neck

How Long Does It Take to Get Spinal Tap Results for MS?

The fluid from your lumbar puncture will be sent to a laboratory for analysis. How long it takes to get results depends on your healthcare facility, but your provider will typically call you within a few days or weeks. Based on the results, you can discuss plans for follow-up, including any additional testing.

Connect With Others Who Understand

On MyMSTeam, the social network for people with multiple sclerosis and their loved ones, more than 218,000 members come together to ask questions, offer advice and support, and share their stories with others who understand life with MS.

Did you undergo a spinal tap during your diagnostic process? Share your experience in the comments below, or start a conversation by posting on your Activities page.