Fellows' tool · MS diagnosis
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McDonald criteria checker: 2017 vs 2024

Created by Dr. Patricia M. Riccio

Enter what the patient has. Both verdicts update as you click, with the reason for each and what would change the 2024 answer. It assumes the presentation is typical for its category and that there is no better explanation.

Examples
Presentation

Non-specific symptoms include headache, paroxysmal symptoms, seizures, or anything that is not a typical attack or progression.

Regions with typical lesions

Typical means ovoid, 3 mm or more, in the right place. Symptomatic lesions count. Count regions, not lesions.

Time and CSF

2017 needs the enhancing lesion alongside non-enhancing ones. This tool assumes there are other, non-enhancing lesions.

Susceptibility imaging

Select-6: 6 or more CVS-positive lesions, or a majority when there are fewer than 10 lesions.

Patient context
Definitions used here
Dissemination in space (DIS)

Typical lesions in 2 or more regions. 2017 has 4 regions. 2024 adds the optic nerve as a fifth. In progressive onset, 2 or more cord lesions count as 2 regions (2024).

Dissemination in time (DIT)

2017: enhancing and non-enhancing lesions together, a new lesion on follow-up, or a second attack. OCB can substitute. 2024: one new T2 lesion, one enhancing lesion, or a clinical attack. No longer mandatory.

Positive CSF

CSF-restricted oligoclonal bands (2 or more). In 2024, a kFLC index of 6.1 or more is interchangeable with OCB.

Central vein sign, Select-6

A thin dark line or dot running centrally through the lesion, seen in two planes on T2* or SWI. Positive with 6 or more CVS lesions. With fewer than 10 lesions, CVS lesions must be the majority. Under 18: more than 50% of T2 lesions.

Paramagnetic rim lesion

A rim around at least two thirds of a non-enhancing lesion on phase images. In 2024 it counts only when a single region is involved, paired with DIT or positive CSF. Not for RIS.

Optic nerve evidence

A short intrinsic MRI lesion, an OCT inter-eye difference (pRNFL 6 µm or more, GCIPL 4 µm or more), or VEP delay or asymmetry. Not if chiasmal, perineural, or longitudinally extensive.

Age 50 or older, vascular risk, headache

2024 strongly recommends a spinal cord lesion, positive CSF, or CVS Select-6 before confirming MS. Vascular risk: hypertension, smoking, diabetes, hyperlipidemia, or macrovascular disease.

Children

The same framework applies. Test MOG-IgG in all children under 12. Do not apply the criteria at an ADEM presentation: wait for a second typical attack or new lesions more than 90 days later.

2017 primary progressive MS

One year of progression plus 2 of 3: a typical brain lesion (periventricular, juxtacortical, or infratentorial), 2 or more cord lesions, or CSF-restricted OCB.