What are the McDonald criteria for Multiple Sclerosis (MS)?

From the Guidelines

The McDonald criteria are diagnostic guidelines used to diagnose multiple sclerosis (MS), focusing on demonstrating lesion dissemination in both space (DIS) and time (DIT) using clinical and MRI findings, as outlined in the 2017 revised criteria 1.

Key Criteria

• For DIS, lesions must be present in at least two of four CNS regions: periventricular, juxtacortical, infratentorial, or spinal cord.
• For DIT, there must be simultaneous presence of enhancing and non-enhancing lesions, or new T2 or enhancing lesions on follow-up MRI.
• The 2017 revised criteria also include the presence of oligoclonal bands in CSF as evidence of DIT, and allow symptomatic lesions to count toward DIS and DIT.
• Cortical lesions can be used alongside juxtacortical lesions for DIS.

Diagnostic Considerations

• A diagnosis requires ruling out alternative explanations for the neurological symptoms.
• The criteria are particularly useful in cases of clinically isolated syndrome (CIS), where they help determine if a patient with a first demyelinating event has MS.
• Early diagnosis enables prompt treatment initiation, which can slow disease progression and reduce disability, as supported by recent guidelines 1.

MRI Interpretation

• Focal white matter lesions, which are hyperintense on T2-weighted scans, are among the pathological hallmarks of multiple sclerosis.
• Current MRI criteria for multiple sclerosis are based on imaging features that are characteristic of the disease, but are not sufficiently specific.
• Emerging data suggest that advanced MRI sequences can enhance our ability to distinguish key, previously established characteristics of multiple sclerosis (e.g. cortical or perivenular lesions) that will enhance diagnosis because they are highly specific 1.

From the Research

McDonald Criteria for MS

The McDonald criteria for the diagnosis of multiple sclerosis (MS) have undergone revisions over the years to incorporate new scientific advances and improve diagnostic accuracy.

• The 2017 revisions of the McDonald criteria continue to apply primarily to patients experiencing a typical clinically isolated syndrome, define what is needed to fulfill dissemination in time and space of lesions in the CNS, and stress the need for no better explanation for the presentation 2.
• Key changes in the 2017 revisions include the inclusion of cerebrospinal fluid (CSF) oligoclonal bands as evidence of dissemination in time in a patient with dissemination in space gathered by clinical or magnetic resonance examination 3.
• The distinction between asymptomatic and symptomatic lesions in counting for evidence of dissemination in space or time in supra, infratentorial, and spinal cord syndrome has been abandoned, and cortical lesions can be used to demonstrate dissemination in space 3.

Diagnostic Criteria

The diagnostic criteria for MS using the McDonald criteria involve:

• Clinical or MRI demonstration of dissemination in space, which can be fulfilled by the presence of one or more T2 lesions in at least two of the following areas: periventricular, juxtacortical, infratentorial, or spinal cord 2.
• Dissemination in time, which can be demonstrated by the presence of a new T2 lesion on a follow-up MRI, or by the presence of CSF-specific oligoclonal bands 2, 4.
• The presence of CSF-specific oligoclonal bands allows a diagnosis of multiple sclerosis in patients with a typical clinically isolated syndrome and clinical or MRI demonstration of dissemination in space 2.

Research and Validation

Research to further refine the McDonald criteria should focus on:

• Optic nerve involvement 2.
• Validation in diverse populations 2.
• Incorporation of advanced imaging, neurophysiological, and body fluid markers 2.
• The value of oligoclonal bands in the context of the McDonald criteria, particularly in patients fulfilling exclusively dissemination in space at baseline 4.