From the Guidelines
The McDonald criteria are the standard diagnostic guidelines for multiple sclerosis (MS), requiring evidence of central nervous system damage in different locations (dissemination in space) and at different times (dissemination in time) as outlined in the 2010 revision 1. To diagnose MS using the McDonald criteria, a patient must meet specific requirements based on their MS subtype. For relapsing-remitting MS, this involves having one or more lesions in each of two or more characteristic locations, such as the posterior fossa, juxtacortical regions, periventricular regions, or spinal cord, and demonstrating dissemination in time through new T2 and/or gadolinium-enhancing lesions on follow-up MRI or the simultaneous presence of asymptomatic gadolinium-enhancing and nonenhancing lesions at any time 1. Key points to consider in applying the McDonald criteria include:
- The importance of MRI in demonstrating dissemination in space and time, with characteristic locations for MS lesions including the posterior fossa, juxtacortical regions, periventricular regions, and spinal cord 1.
- The role of cerebrospinal fluid analysis, particularly in cases where MRI findings are not definitive, with evidence of oligoclonal IgG bands and/or increased IgG index supporting the diagnosis of MS 1.
- The challenges in diagnosing primary progressive MS, where brain MRI features can be normal and spinal cord lesions might not be detected, necessitating careful consideration of clinical and paraclinical findings 1. The 2010 McDonald criteria have improved the diagnostic process for relapsing-remitting MS but exhibit limitations in primary progressive MS, highlighting the need for careful interpretation of MRI findings and consideration of clinical and laboratory information 1.
From the Research
Overview of McDonald Criteria
- The McDonald criteria are a set of diagnostic criteria for multiple sclerosis (MS) that have undergone several revisions, with the most recent being the 2017 revisions 2, 3.
- The criteria aim to provide guidance for clinicians and researchers in diagnosing MS, and they define what is needed to fulfill dissemination in time and space of lesions in the central nervous system (CNS) 2.
Key Changes in the 2017 Revisions
- The presence of CSF-specific oligoclonal bands allows for a diagnosis of MS in patients with a typical clinically isolated syndrome and clinical or MRI demonstration of dissemination in space 2, 3.
- Symptomatic lesions can be used to demonstrate dissemination in space or time in patients with supratentorial, infratentorial, or spinal cord syndrome 2, 3.
- Cortical lesions can be used to demonstrate dissemination in space 2, 3.
Previous Revisions and Studies
- The 2010 revisions to the McDonald criteria simplified the use of imaging for demonstration of dissemination of CNS lesions in space and time, and allowed for earlier diagnosis and more uniform use 4.
- A study published in 2003 validated the diagnostic magnetic resonance imaging criteria for MS and response to interferon beta1a, and found that the modified Barkhof criteria were effective in predicting conversion to clinically definite MS 5.
Future Directions and Emerging MRI Features
- Research should focus on optic nerve involvement, validation in diverse populations, and incorporation of advanced imaging, neurophysiological, and body fluid markers 2.
- Emerging MRI features such as the central vein sign and iron rims may improve the specificity of MRI in the diagnosis of MS and minimize misdiagnosis 6.