The latest revision is the 2024 McDonald criteria, published in The Lancet Neurology in September 2025. These criteria update the 2017 version and incorporate new MRI biomarkers and cerebrospinal fluid tests to support earlier, more accurate diagnosis of multiple sclerosis.
The criteria apply to patients with suspected MS, including relapsing and progressive presentations. Diagnosis requires an appropriate clinical and paraclinical assessment and exclusion of a better explanation for the findings.
Key changes in the 2024 revision
| Feature | 2024 McDonald criteria |
| Anatomical regions | Five CNS regions, adding the optic nerve |
| Dissemination in space (DIS) | Lesions in characteristic CNS locations |
| Dissemination in time (DIT) | Still relevant, but no longer mandatory in every diagnostic pathway |
| CSF biomarkers | Oligoclonal bands or an elevated kappa free-light-chain index can provide supportive evidence |
| Advanced MRI biomarkers | Central vein sign (CVS) and paramagnetic rim lesions (PRLs) |
| Clinical presentations | Expanded pathways include selected asymptomatic and radiologically isolated presentations |
The five anatomical regions
- Periventricular: Lesions directly contacting the lateral ventricles.
- Cortical or juxtacortical: Lesions involving the cortex or immediately adjacent white matter.
- Infratentorial: Lesions in the brainstem or cerebellum.
- Spinal cord: Characteristic intramedullary lesions.
- Optic nerve: Evidence of optic nerve involvement, assessed using appropriate MRI, optical coherence tomography (OCT), or visual evoked potentials (VEPs).
The optic nerve is the principal new anatomical region introduced in the 2024 revision.
How diagnosis is established
The diagnostic pathway integrates clinical presentation, MRI distribution, and supportive biomarkers.
- Dissemination in space: characteristic lesions in multiple CNS regions, according to the applicable diagnostic pathway.
- Dissemination in time: evidence of disease activity at different times, such as new MRI lesions or simultaneous enhancing and nonenhancing lesions.
- Supportive biomarkers: CSF-restricted oligoclonal bands, an elevated CSF kappa free-light-chain index, the central vein sign, or paramagnetic rim lesions in specified circumstances.
Importantly, the 2024 criteria allow some patients to meet diagnostic requirements without demonstrating dissemination in time. In certain pathways, characteristic lesions across four of the five CNS regions can establish the diagnosis without DIT, provided the other requirements are met. Other pathways use additional clinical or paraclinical evidence.
Differential diagnosis and precautions
Before diagnosing MS, clinicians should consider alternative conditions that can mimic it, including:
- Neuromyelitis optica spectrum disorder (AQP4-IgG).
- MOG antibody-associated disease (MOGAD).
- Small-vessel ischemic disease and migraine-associated white-matter lesions.
- Other inflammatory, infectious, metabolic or genetic disorders.
The criteria should be applied by clinicians experienced in demyelinating disease, particularly in atypical presentations, children, and adults over 50 years of age.
References:
- Montalban X, et al. Diagnosis of multiple sclerosis: 2024 revisions of the McDonald criteria. The Lancet Neurology. 2025;24(10):850–865. [Medline]
- Zettl UK, Rommer PS, Wattjes MP, Tumani H, Hecker M. Concerns regarding the 2024 revisions of the McDonald criteria for diagnosis of multiple sclerosis. Lancet Neurol. 2026 Jun;25(6):542. [Medline]
Created Oct 29, 2026.