Diagnosis of multiple sclerosis: 2024 revisions of the McDonald criteria

In multiple sclerosis, the McDonald criteria are the standard criteria for disease diagnosis; according to these criteria, patients must present with multiple lesions in the central nervous system that are disseminated in space.

“In MS, the McDonald criteria are the standard criteria for disease diagnosis. According to these criteria, patients must present with multiple lesions in the central nervous system (CNS) that are disseminated in space (Montalban et al. 2025).”

The 2024 revisions aim to increase diagnostic sensitivity while incorporating additional features intended to preserve, even increase, diagnostic specificity, thereby enabling an earlier and more accurate diagnosis of MS.

“These revisions aim to increase diagnostic sensitivity while incorporating additional features intended to preserve, even increase, diagnostic specificity, thereby enabling an earlier and more accurate diagnosis of MS.8”

The 2024 revisions of the McDonald diagnostic criteria for multiple sclerosis include the optic nerve as a distinct fifth anatomical location for meeting dissemination in space criteria for relapsing- and progressive-onset MS.

“The committee voted unanimously to include the optic nerve as a distinct, fifth anatomical location for meeting dissemination in space (DIS) criteria for relapsingand progressive-onset MS. 25”

In the 2024 McDonald criteria for multiple sclerosis diagnosis, the optic nerve is added to the four previously designated dissemination-in-space regions (periventricular, juxtacortical/cortical, infratentorial, spinal cord), and dissemination-in-space criteria can be met with involvement of at least 2 of these 5 regions.

“In the 2024 revisions of the McDonald criteria for diagnosis of multiple sclerosis, the optic nerve is added to the four previously designated DIS regions: peri-ventricular, juxta-cortical/cortical, infra-tentorial and spinal cord regions. DIS criteria for MS diagnosis can now be met with involvement of ≥ 2/5 of these regions (Panel 1). 25,26”

The optic nerve is incorporated as the fifth neuroanatomical topography for establishing DIS in the 2024-revised McDonald criteria.

“The optic nerve is incorporated as the fifth neuroanatomical topography for establishing DIS, complementing periventricular, (juxta-)cortical, infratentorial, and spinal cord regions.8, 9, 10”

The 2024 revision introduces substantial modifications that reflect advances in neuroimaging, neurophysiological assessment, and biomarker discovery.

“The 2024 revision introduces substantial modifications that reflect advances in neuroimaging, neurophysiological assessment, and biomarker discovery.8”

In CSF, intrathecal inflammation can be demonstrated by oligoclonal bands (OCB) or by kappa free light chains (KFLC).

“in CSF, intrathecal inflammation can be demonstrated by oligoclonal bands (OCB) or by kappa free light chains (KFLC), which represent a complementary biomarker.8, 9, 10, 11, 12”

Optic nerve involvement can be substantiated by VEP, OCT, or MRI in the 2024-revised criteria.

“Optic nerve involvement can be substantiated by visual evoked potentials (VEP), optical coherence tomography (OCT), or MRI thus formally integrating visual pathway assessment into the diagnostic framework.8, 9, 10”

The 2024-revised criteria permit a diagnosis of MS in individuals with RIS and in people with non-specific presentations.

“Lastly, the criteria now permit a diagnosis of MS in individuals with incidental MRI findings suggestive of chronic inflammatory demyelination (RIS: radiologically isolated syndrome) and in people with non-specific presentations.8,13”

Under the 2024-revised criteria, MS can be diagnosed when ≥4 typical topographies are affected.

“MS can be diagnosed when ≥4 typical topographies are affected.8, 9, 10”