Diagnosing Multiple Sclerosis: How Lumbar Puncture Works

Written by Robin Madell | Published on January 15, 2014
Medically Reviewed by George Krucik, MD, MBA on January 15, 2014

Find out when this test is necessary and what it can reveal about you.

Steps to Diagnosis

Diagnosing multiple sclerosis (MS) takes several steps. One of the first steps is a general medical evaluation that may include a physical exam, a discussion of any symptoms, and your medical history. 

If your doctor suspects that you could have MS, you may need to take one or more tests, including a lumbar puncture test.

Importance of Testing

Because MS can share symptoms with other health problems, your doctor will need to determine whether it’s MS that’s causing your symptoms. Through diagnostic testing, your doctor may be able to tell whether or not you have another health condition instead of MS.

Tests that your doctor might recommend to rule out or confirm a diagnosis of MS include:

  • lumbar puncture test
  • blood tests
  • MRI (magnetic resonance imaging) test
  • evoked potential test 

What’s a Spinal Tap?

A lumber puncture is also called a spinal tap. A spinal tap is one way a doctor can try to diagnose MS.

During a lumbar puncture (spinal tap), your healthcare team will test your spinal fluid for signs of MS. 

To do so, your doctor must first remove spinal fluid from your back for testing in a lab. This involves inserting a needle into the lower part of your back.

What to Expect in Lumbar Puncture

The process of a spinal tap allows your doctor to remove some of your spinal fluid for testing.

The fluid is generally drawn between two of your vertebrae in your lower spine using a spinal needle. This is often the third and fourth lumbar vertebrae. 

Your doctor will ensure that the needle is positioned in the right place between your spinal cord and the cord’s covering, called the meninges.

Why Get a Spinal Tap?

According to the Cleveland Clinic, a lumbar puncture is the only way to directly and accurately determine how much inflammation you may have in your spinal cord region as well as your brain.

It also shows the activity of your immune system in these parts of your body, which is important for diagnosing MS. By taking a lumbar puncture test, you provide your doctor with valuable information for diagnosing MS. 

What Lumbar Puncture Can Reveal

A spinal tap can reveal when the amount of protein, white blood cells, or myelin in your body has become too high.

It might also reveal that the fluid in your spine contains an abnormal level of antibodies.

Also, analyzing your spinal fluid can show your doctor whether you might have another condition and not MS. Some viruses can cause signs and symptoms that look like MS, but aren’t.

Limits to Lumbar Puncture

To be the most useful, a lumbar puncture should be given along with other tests.

This is because by itself, a spinal tap can’t definitively help your doctor rule out or confirm whether you have MS.

A lumbar puncture can reveal signs that you have a problem with your autoimmune system. But other conditions that affect your nervous system, like lymphoma and Lyme disease, might also show high levels of antibodies and proteins in your spinal fluid. 

Difficult to Diagnose

MS is often tough for doctors to diagnose. This is because a spinal tap alone can’t prove whether you have MS or not. In fact, there is no single test that can confirm or deny a diagnosis.

But your doctor can use more than one test, including a lumbar puncture, to diagnose MS. If testing your spinal fluid reveals abnormalities, your doctor may require other tests.

Your doctor might request an MRI to detect lesions on your brain or spinal cord. They may also ask for an evoked potential test to help detect nerve damage. Your doctor can determine whether further tests are needed to confirm a diagnosis.

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