Updated McDonald's criteria (2024 version) — official publication and key changes

The most important event of the year for MS diagnosis: the McDonald Criteria update (for the first time, optic nerve damage is allowed to be counted as the fifth anatomical area, approaches to DIS/DIT and the use of biomarkers have been clarified). This is intended to speed up and standardize diagnosis in adults and children. For patients, this means fewer “gray areas” and an earlier start to therapy. Here's what's new and why it matters.

1. Consolidation of diagnostics for different forms and age groups

The new version aims to provide a unified approach to MS diagnostics, regardless of whether it is a relapsing-remitting or progressive form, or whether it affects children, adults, or the elderly.

Special attention is given to people aged ≥50, individuals with vascular diseases, and patients with radiologically isolated syndrome (RIS) — i.e., when damage is visible on MRI but there are no clinical symptoms yet.

2. Addition of a new location for dissemination in space (DIS)

Previously, four anatomical areas were used: periventricular, juxtacortical/cortical, infratentorial, and spinal cord.

In version 2024, the optic nerve is added to this list as the fifth location.

This means that damage to the optic nerve (clinically or by MRI/OCT/VEP) can be considered as evidence of CNS involvement in the diagnosis of MS.

3. New RF biomarkers and MRI signs

Central Vein Sign (CVS) — a sign of a central vein within an MRI lesion: can now be included as a criterion to support the diagnosis.

Paramagnetic Rim Lesions (PRL) — an area of chronically active lesion with microglia/iron at the edge of the lesion: also taken into account in specific circumstances.

In cerebrospinal fluid (CSF), the κ-light chain index (kappa free-light chains, kFLC) is added as an alternative to the existing role of oligoclonal bands (OCB).

4. Less need to wait for a new attack or new lesion

In previous versions (2017), confirmation of dissemination in time (DIT) often required either a new clinical attack or a new MRI change.

In version 2024: under certain circumstances, DIT may be optional. For example, if there are lesions in 4-5 locations, or if there are specific biomarkers (CVS/PRL/kFLC), the diagnosis can be made earlier.

5. Better differentiation in complex groups

In groups of children, people over 50, or those with comorbidities (e.g., vascular disease), more guidance is now provided to avoid misdiagnosis.

For RIS: a person without pronounced symptoms but with an MRI typical for MS may be diagnosed with MS earlier if the data meets the criteria.

Practical significance for patients and clinics

MS can be diagnosed earlier, allowing treatment to start sooner — and early treatment is associated with better outcomes.

Greater accuracy and less delay — but this comes with the need for caution: the risk of misdiagnosis also exists, so proper interpretation is important.

Patients who were previously classified as “has lesions on MRI but no symptoms (RIS)” can now be diagnosed and begin discussing treatment earlier.

Clinicians need to consider new methods (e.g., OCT of the optic nerve, specific MRI sequences for CVS/PRL, kFLC analysis), which requires access to the appropriate equipment and expertise.

Read more