The McDonald Criteria was first established in 2001 by neurologist Ian McDonald and a team of researchers as a standard means of diagnosing multiple sclerosis (MS) with sensitivity and speed. (It is also known as the International Panel on MS Diagnosis, and the original and subsequent panels were, at least in part, organized by the National Multiple Sclerosis Society.)
The McDonald Criteria is distinguished by incorporating clinical evaluation with magnetic resonance imaging (MRI) scans in establishing MS. But, like an earlier approach, it too requires:
- Evidence of damage to the central nervous system (CNS; the brain, spinal cord and optic nerves) that is “disseminated in time,” meaning damage that occurs on different dates;
- Evidence of damage “disseminated in space,” or found on two or more parts of the CNS.
A 2010 revision to the McDonald Criteria (which followed a 2005 update) reflected better understanding of MS and improved MRI techniques and made possible a faster diagnosis — one that is, for a first time, potentially based on only one demyelinating relapse or attack provided certain criteria are met. These new criteria are dissemination in time, if two lesions are evident at a first attack, and dissemination in both time and space if only one lesion is evident.
This change was key because of the importance of moving patients with confirmed disease quickly onto disease-modifying therapies that may slow disease progression.
The Schumacher Criteria (1965) was the first official method for diagnosing MS and based on clinical findings. Later, the Poser Criteria (1983) standardized the use of diagnostic tests such as evoked potentials (EP) and a spinal tap, allowing confirmation of damage disseminated in space (DIS) and disseminated in time (DIT). Poser could also distinguish among possible, probably, or definite MS in a patient.
2010 revisions to the McDonald Criteria
Largely, the 2010 revision reflected the need to simplify whether myelin damage seen on an MRI according to DIS and/or DIT was distinctive of MS. The revision also improves the criteria’s applicability to other populations (pediatric, Asian and Latin Americans), since it was developed using a white and Western patient population. Further tests for these populations are specified.
Emphasis in this revision was also placed on the criteria being applied only to patients with clinically isolated syndrome (CIS) suggestive of MS, or with symptoms consistent with a CNS inflammatory demyelination disease, the National MS Society reports.
Essential MRI findings to confirm MS based on one relapse (DIS and DIT)
Under the McDonald Criteria (revised), an MS diagnosis is likely if myelin damage is disseminated in space, as seen in an MRI as:
- At least one T2 bright lesion in at least two or four CNS locations: the juxtacortical, perventricular and infratentorial areas of the brain, and the spinal cord. (T2 is the most common MRI scan used to diagnose MS, and to detect areas of myelin damage, old and new, in the brain and spinal cord).
- These lesions need not be gadolinium enhanced (contrast material).
Regarding myelin damage dissemination in time, the 2010 revision simplified MRI evidence to be:
- A new T2 and/or gadolinium-enhancing damage on follow-up MRI, compared to a baseline scan (irrespective of time since baseline). The 2005 revision had required at least 30 days to pass between the initial and first attack.
- Simultaneous presence of asymptomatic gadolinium-enhancing and non-enhancing damage at any time.
Cerebrospinal fluid (CSF) values in MS diagnosis
Positive CSF values used to determine an MS diagnosis include the presence of two or more oligoclonal bands (proteins indicating inflammation) or a high immunoglobulin (IgG) index (common in MS patients).
Primary progressive MS and the McDonald Criteria
The 2010 revision panel recognized that progressive primary MS (PPMS) has special diagnostic needs. Specifically, the 2010 revision calls for at least one year of demonstrated progression (done prospectively or retrospectively), plus two of the following three findings:
- Evidence of DIS in the brain, seen in at last one T2 lesion in the three key brain regions (periventricular, juxtacortical or infratentorial)
- Evidence of DIS in the spinal cord, based on at least two T2 lesions DIS (≥ 2 T2 damage);
- Positive CSF involvement, again as seen in the presence of oligoclonal bands and/or a high IgG index.
The National MS Society provides a tip sheet summarizing key points in the 2010 revised McDonald Criteria, which was organized and supported by the MS Society and the European Committee for Treatment and Research in Multiple Sclerosis. The panel was led by Chris Polman, a doctor at the Free University of Amsterdam.
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