How Multiple Sclerosis Is Diagnosed

Diagnosing multiple sclerosis (MS) is complex and challenging. Everyone's symptoms are unique. And they can be similar to many other diseases.

No single test can confirm MS. Instead, doctors use a variety of diagnostic methods. They include neurological tests, imaging, and blood tests.

The McDonald Criteria are a big part of this process. A 2017 revision added guidelines that make early diagnosis more likely.

That means you can start treatment earlier. This may slow down the disease.

This article walks you through the long MS diagnostic process and what other conditions may be possible.

What Is Multiple Sclerosis?

Multiple sclerosis is an autoimmune disease. That means your immune system is attacking a part of your body. In MS, it attacks an important coating on the nerves called the myelin sheath.

How Multiple Sclerosis Is Diagnosed
Verywell / Emily Roberts

Medical History

Your medical history is made up of your current health and past illness and injuries. Your neurologist will ask a lot of questions about symptoms you're having or have had before.

It's a good idea to keep a symptom log before this appointment. Include information on how long it lasted, time of day, and what you were doing. Even list symptoms other doctors said not to worry about.

Also:

  • Your doctor will also ask about any medications you're taking.
  • Bring the results of prior medical tests or make sure your doctor has them.
  • Be ready to answer about your drug and alcohol use and other health issues.
  • Expect the doctor to ask about your family health history.

All of this will help a neurologist decide whether MS is likely. The Doctor Discussion Guide below can help you have a productive conversation.

Multiple Sclerosis Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Woman

McDonald Criteria

Doctors use the McDonald Criteria to diagnose MS. Criteria have grown more accurate. And they can now diagnose you earlier.

An MS diagnosis involves lesions. These are damaged or scarred areas of the central nervous system (CNS). The CNS includes your brain and spinal nerves.

Attacks from the immune system cause inflammation. Inflammation causes MS lesions.

Your doctor can diagnose MS if they find:

  • At least two lesions in different parts of the CNS
  • Damage of various ages
  • No evidence of other conditions

They gather evidence through:

  • Neurological exam
  • Evoked potentials testing
  • MRI
  • Lumbar puncture
  • Ruling out other possible conditions

Recap

Your medical history and the McDonald Criteria will guide your doctor's diagnostic process. They'll look for multiple areas of damage that vary in age plus other conditions that may explain your symptoms.

Neurological Exam

This is performed in the neurologist's office through a variety of simple tests. The doctor is checking your:

  • Coordination
  • Strength
  • Reflexes
  • Sensation
  • Cranial nerve function

What Are Cranial Nerves?

Cranial nerves are those that originate in the brain rather than from the spinal cord. They control your senses (e.g., vision and hearing) and your ability to talk and swallow.

You'll be asked to do things like touching your nose and then the doctor's finger. They'll touch you with various instruments to measure your sensation or response.

The exam will probably last between 45 minutes and two hours.

Evoked Potential Tests

Evoked potential tests (EPTs) measure:

  • How quickly nerve signals reach your brain
  • How big the response is

Impulses move more slowly along damaged nerves. That includes those with myelin damage from MS.

These tests are becoming less popular. MRIs are often better. But EPTs are better than MRIs at viewing places. That includes the optic nerve.

Three evoked potential tests can be used to diagnose MS. They each use electrodes on your scalp and track responses to different stimuli.

  • Visual Evoked Potentials (VEPs): Find optic nerve damage by measuring the response to flashing lights.
  • Somatosensory Evoked Potentials (SSEP): Measures the response to physical sensation.
  • Brainstem Auditory Evoked Potentials (BAEP): Uses sounds through headphones to measure auditory (hearing) nerve function.

Magnetic Resonance Imaging

MRIs use magnetic waves to produce images of the brain and spinal cord.

An injected contrast material called gadolinium reacts to inflammation. During a gadolinium MRI, active or recent lesions appear lit up.

MRI is considered the best test for diagnosing MS. It finds lesions in more than 95% of people with the condition.

False Negatives/False Positives

MRI leads to false negatives in about 5% of MS cases. Other times, age-related damage or other conditions (migraine, brain trauma) look like MS lesions. This produces false positives. That's why doctors use more than one test.

Lumbar Puncture

Lumbar puncture is also called a spinal tap. It involves withdrawing cerebrospinal fluid (CSF) from your spinal column. The doctor does this with a small needle inserted between vertebrae in your lower back.

In MS, the CSF will have what's called oligoclonal bands. Those are changes due to high levels of certain antibodies. They result from increased immune-system activity.

This test is positive in up to 90% of people with MS. It's not specific to MS, though. So a positive result could point to another condition.

Not everyone needs a lumbar puncture to be diagnosed with MS. However, it can help rule out other diagnoses.

Recap

Central nervous system damage from MS can be identified through evoked potentials testing, MRI, and possibly lumbar puncture.

Other Possible Conditions

MS has myriad hard-to-describe symptoms. They come and go. And they can't be "seen" by tests. MS also shares symptoms with lots of medical conditions.

Ruling out other possibilities can mean bloodwork, imaging, and other tests. Diseases that mimic MS include:

Clues may suggest another diagnosis. That may prompt a doctor to look first in other directions.

For instance, MS is less likely if:

  • You're under 15
  • You're over 60
  • Tingling, numbness, and weakness come with serious back pain
  • Peripheral nerves (those outside the spinal column) are involved

MS is more likely if you have:

  • Symptoms in at least two parts of the central nervous system that come and go
  • Worse neurological symptoms due to heat (Uhthoff's phenomenon)
  • Flares of neurological symptoms that resolve completely or partially

Relapsing-remitting is the most common form of MS. It affects 85% of people with the disease.

Summary

MS is difficult to diagnose. There's no single, reliable test. Doctors use symptoms, medical history, a neurological exam, and several that to identify MS lesions. These include evoked potentials, MRI, and lumbar puncture. You'll also be tested for conditions with similar symptoms.

A Word From Verywell

MS can be a tricky disease to definitively diagnose. The process requires patience.

It's important to find a neurologist you're comfortable with and have confidence in. If you do have MS, they'll likely be your partner in health for a long time.

Frequently Asked Questions

  • What do people usually experience as their first symptom of MS?

    The most common first symptoms of MS are:

    • Vision problems
    • Numbness or tingling in the face, body, or limbs
    • Dysesthesia (a tightening sensation around your torso), also known as the "MS hug"
  • How long can someone live with MS?

    On average, people with MS live about seven fewer years than people without it. But the gap is closing thanks to earlier diagnoses and better treatments.

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Article Sources
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