New Ways to Diagnose Multiple Sclerosis (MS): What Patients Need to Know About the 2024 McDonald Criteria

Doctors have updated the guidelines for diagnosing multiple sclerosis (MS) in 2024, known as the "McDonald Criteria". New changes now include optic nerve damage, spinal fluid tests, and detailed MRI features. These updates can help you get diagnosed more accurately and start treatment earlier.

If you have MS or think you might, here’s a clear, patient-friendly summary of what these changes mean for you.

Why does the 2024 Update of the McDonald Criteria Matter?

The new guidelines help doctors identify MS earlier and more accurately by using advanced tests like MRIs and blood or spinal fluid tests. Early diagnosis means earlier treatment, which can slow MS progression and improve your quality of life.

Key Changes and Why They Matter

1. MRI Scans Are Now Required

Previously, MS could be diagnosed based solely on clinical symptoms and findings. Doctors now always need MRI images to confirm MS. Symptoms alone aren't enough.

Why it matters:

An MRI clearly shows if you have MS-related damage (lesions) in your brain or spinal cord and helps your neurologist give you the correct diagnosis.

2. The Optic Nerve Now Counts Toward Diagnosis

Damage to the optic nerve (the nerve connecting your eye to your brain) is now considered a key sign of MS.

In the 2017 rules, even if your optic nerve was clearly inflamed, it didn’t count toward diagnosis. That’s now changed.

To detect these changes, your neurologist may use:

• MRI scans of the optic nerve
• OCT scans (quick, painless eye imaging)
• Visual evoked potentials (to test how fast your brain reacts to visual signals)

Why it matters:

If you’ve had optic neuritis — blurry vision, pain when moving your eye, or loss of color vision — that can now be used as evidence of MS.

3. Easier, Faster Spinal Fluid Test: Kappa Free Light Chains

In the past, doctors looked for oligoclonal bands in spinal fluid to support MS diagnosis. These are immune proteins that show inflammation in the central nervous system.

Now, a newer and simpler test can also be used, called Kappa-Free Light Chains (kFLC). These immune markers are just as reliable as oligoclonal bands but may show up sooner and be easier to test.

Why it matters:

This test is quicker, simpler, and more reliable than oligoclonal bands, helping you get answers faster and with more confidence.

4. New MRI Signs to Identify MS

Two new MRI features now help confirm MS — especially when diagnosis isn’t crystal clear:

• Central Vein Sign: MS lesions often form around small blood vessels. If a vein runs through the middle of a brain spot (lesion), it supports an MS diagnosis.
• Paramagnetic Rim Lesions: These lesions have a dark rim on special MRI scans, which shows ongoing inflammation—something seen almost only in MS.

Why it matters:

These signs help reduce misdiagnosis and may prevent unnecessary treatment for other look-alike conditions like migraines or age-related changes.

5. Diagnosing MS Even Without Symptoms (RIS)

Sometimes MRIs show MS-like lesions even if you haven't felt any symptoms. Doctors call this Radiologically Isolated Syndrome (RIS). In the past, doctors had to wait for symptoms to appear before making an MS diagnosis.

Now, if certain criteria are met, RIS can be diagnosed as MS:

You must have:

• Lesions in different MS-related locations (dissemination in space)
• AND one of the following:
  • Lesions at different times (dissemination in time)
  • Positive spinal fluid biomarkers
  • Six or more lesions with the Central Vein Sign

Why it matters:

This can help you begin treatment earlier, even before symptoms appear, potentially slowing the disease.

6. Stricter Checks for Older Adults

As we age, our brains develop white matter spots for many reasons—like high blood pressure, diabetes, or migraines. These changes can mimic MS.

For people over 50 or those with vascular risk factors (like high blood pressure, diabetes or cholesterol), doctors now need:

• Lesions in the spinal cord
• A positive spinal fluid test
• Or MRI features like the Central Vein Sign

Why it matters:

This ensures MS is diagnosed accurately and prevents unnecessary treatment for unrelated conditions.

What About the 2017 Criteria?

As we are waiting for the full peer-reviewed publication of the new 2024 McDonald Criteria, here’s a simplified version of how MS was diagnosed under the 2017 McDonald Criteria (and still is—along with the new 2024 updates):

To be diagnosed with MS, you need:

1. Evidence of damage in multiple areas of the central nervous system, typically associated with MS, called Dissemination in Space (DIS)

• Areas include:
  • Periventricular (near the brain’s fluid-filled spaces)
  • Juxtacortical or cortical (near the brain’s surface)
  • Infratentorial (brainstem or cerebellum)
  • Spinal cord
  • (2024 update: now includes optic nerve)

2. Evidence that damage happened at different times, called Dissemination in Time (DIT)

• Shown by:
  • A mix of new and old lesions on MRI
  • OR a positive spinal fluid test (OCBs or kappa chains with the 2024 update)

3. Clinical attacks (flare-ups) or symptoms help determine which pathway of the criteria applies.
4. Primary Progressive MS (a different form of MS) has its own criteria:

• 1 year of gradual worsening
• Plus 2 out of 3: spinal cord lesions, brain lesions, or spinal fluid evidence

What Do These Changes Mean for You?

• Earlier Diagnosis And Treatment: The new criteria may allow for earlier MS diagnosis, potentially leading to earlier treatment and better long-term outcomes.

• Increased Accuracy: By incorporating new MRI signs and refining existing criteria, the 2024 revisions aim to reduce misdiagnosis.

• Potentially Fewer Tests: Simplified criteria may mean fewer MRI scans or other tests for some patients.

• Broader Scope: The inclusion of the optic nerve and new MRI signs provides a more thorough assessment of potential MS activity and may help diagnose MS in individuals who previously might not have met the older criteria.

• More Safeguards Against Misdiagnosis: Older patients or those with vascular risk factors may need to undergo more comprehensive evaluation to ensure accurate diagnosis.

Next Steps If You're Concerned About MS

• See an MS Specialist: A neurologist specializing in MS can use these new guidelines to help you.
• Check Previous MRIs: Older scans might offer new insights under these guidelines. Always bring your MRI images—not just reports—to appointments. It helps your neurologist give you the most accurate diagnosis.
• Ask about the Kappa Free Light Chains test: If you’re getting a spinal tap getting this test can help your doctor diagnose MS faster.
• Consider Eye Exams: Get your vision checked if you've had vision problems. If you have optic neuritis, it can be a sign of MS.
• Stay Informed: Regularly discuss updates and options with your neurologist.

Final Thoughts

The 2024 McDonald Criteria bring real progress for MS diagnosis. If you’ve been waiting for answers—or were told your MRI “might” show MS — this could be your moment for clarity.

If you have questions about MS, want a second opinion or an updated review of your case, contact Dr. Achillefs Ntranos, our MS specialist. Early action can make a significant difference.