ARTICLE IN BRIEF
A new 2010 version of the McDonald criteria for multiple sclerosis simplifies the MRI criteria for diagnosis of MS.
The standard diagnostic criteria for multiple sclerosis (MS) has been updated, making it simpler to apply and requiring fewer MRI images than an earlier version, experts saying, enabling earlier diagnosis at a lower cost for patients.
The 2005 version of the so-called McDonald criteria was “generally satisfactory, but a bit complex, and that complexity made them a little bit challenging for practicing physicians,” said one of the authors of the new criteria, Fred Lublin, MD, professor of neurology at the Mount Sinai School of Medicine in New York, and director of the Corinne Goldsmith Dickinson Center for Multiple Sclerosis.
The international panel involved in the newest revision reaffirmed the underlying concepts of both the original criteria, from 2001, and the 2005 revision, specifically that the diagnosis of MS can be made based on demonstrating dissemination of lesions in space and time, in the context of symptoms or signs consistent with demyelination. But the newest revision greatly simplifies the imaging findings required for diagnosis. The revision was published in the February Annals of Neurology.
In the previous McDonald criteria, dissemination of lesions in space (DIS) required three of the following four phenomena: at least one gadolinium-enhancing lesion or T2 hyperintense lesion; at least one infratentorial lesion; at least one juxtacortical lesion; and at least three periventricular lesions. A spinal cord lesion could substitute for any one of the brain lesions.
But studies published since 2005, especially by the European MAGNIMS (Magnetic Imaging in MS) group, offered evidence that the imaging criteria could be relaxed without losing diagnostic accuracy. In the new criteria, Dr. Lublin said, the definition of dissemination in space is demonstrated by at least one T2 lesion in at least two of the following four areas: periventricular, juxtacortical, infratentorial, and spinal cord.
Demonstrating dissemination in time (DIT) is simplified even more significantly, he said. The old criteria required a follow-up MRI 30 days or more after the first clinical episode suggesting demyelination because everything that happened within 30 days of the attack was, by convention, assumed to be part of that attack,” Dr. Lublin said. “That wasn‘t a biological distinction, it was by convention.”
In the revised criteria, DIT can be established in one of two ways. The first way is the appearance of a new lesion on a second scan, regardless of the timing in relation to the initial scan. “What has been shown is that any change [on a scan] carries the same weight, irrespective of timing,” he said.
The second way is the simultaneous presence of asymptomatic gadolinium-enhancing and nonenhancing lesions on a single scan, performed at any time. “This isn‘t dissemination in time,” since it is a single scan, “but it is a marker of dissemination in time,” which, studies have confirmed, “substitute quite nicely for it,” Dr. Lublin said.
Together, the new criteria are “simpler to use, but there is no sacrifice in sensitivity and specificity.”
Dr. Lublin added that it was still possible to make a diagnosis of MS without an MRI. “If a person has clinical evidence of dissemination in space and dissemination in time, then that is satisfactory for a diagnosis of multiple sclerosis. You don‘t have to have any tools other than ears to listen and a brain to analyze, and perhaps a reflex hammer,” but it requires waiting longer to demonstrate clinical dissemination in time. “What the MRI allows us to do is to shorten that time,” he said.
The revised criteria retain the previous diagnostic requirements for primary progressive MS, but with one important change. As before, they require one year of disease progression, plus two positive findings in three criteria: brain MRI, spinal cord MRI, or cerebrospinal fluid antibodies. But instead of the earlier requirement for 9 T2 lesions in the brain, the new criteria require only one T2 lesion in at least one brain area characteristic for MS.
Because the studies leading to the revised criteria were primarily carried out in adult white populations, the revisions are only completely applicable to patients in this group, Dr. Lublin said. Their application to pediatric patients is complex, because while most children present with attacks that closely resemble those in adults, some, especially the youngest patients, do not display an adult-like pattern. In such patients, serial clinical or MRI observations are required to confirm the diagnosis.
In Asian and Latin American populations, neuromyelitis optica (NMO) is a common alternative diagnosis, and testing for anti-aquaporin antibodies is an important part of the clinical work-up. “When you see demyelinating disease in a non-Caucasian population, you have to give consideration to NMO in the right clinical setting, because it is a little more likely to occur in those populations, and MS is less likely to occur,” Dr. Lublin said.
The value of the revised criteria, Dr. Lublin emphasized, was both that they were simpler and they allow earlier diagnosis with good accuracy. “We‘d like to diagnose as early as possible, because we can treat an earlier stage,” a benefit for the health of patients.
Bruce A. Cohen, MD, professor of neurology at the Feinberg School of Medicine at Northwestern University in Chicago, echoed that point in an interview with Neurology Today. “The concern was that the previous criteria were a bit cumbersome to use in clinical practice,” he said, adding that consequently, in many cases, they were not used.
“Realistically, it isn‘t very common in the United States that someone would wait 30 days between the time of their first presentation symptoms and their first MRI scan,” Dr. Cohen said. Negating the first scan for diagnostic purposes would mean the patient would need an additional scan to make the diagnosis, “and I don‘t think people were doing it.”
The value of the new criteria, he said, was that “in some circumstances, you may be able to diagnose a patient at first presentation on the basis of the first MRI scan,” and that can lead to earlier treatment.
“The issue for these criteria is that they do have to be applied thoughtfully. They are predicated on someone with a clinical presentation typical of CNS demyelination,” Dr. Cohen said. MRI lesions discovered incidentally, without clinical findings, “would not necessarily fit these criteria. Recognizing that the clinical presentation is typical of demyelination is important.”
One thing the new criteria cannot do, Dr. Lublin said, was help decide the appropriate choice for initial therapy. “That's much more complicated. One would hope that with advanced imaging metrics, one could identify differences in the underlying pathologic substrate that may occur in MS, and choose a therapy aimed at those abnormalities.” But for now, that remains a hope for the future.
2010 MCDONALD MRI CRITERIA: HIGHLIGHTS
* DIS (lesion dissemination in space) can be demonstrated by ≤ 1 T2 lesion in at least 2 of 4 areas of the CNS: periventribular, juxtacortical, infratentorial, spinal cord
* DIT (lesion dissemination in time) can be demonstrated by: 1) a new T2 and/or gadolinium-enhancing lesion(s) on follow-up MRI, with reference to a baseline scan, irrespective of the timing of the baseline MRI; 2) simultaneous presence of asymptomatic gadolinium-enhancing and nonenhancing lesions at any time
* Diagnosis of primary progressive MS: 1) one year of disease progression (retrospectively or prospectively determined); 2) plus 2 of the following criteria: A) evidence for DIS in the brain based on ≤1 T2 lesions in at least one 1 area characteristic for MS periventricular, juxtacortical, or infratentorial); B) evidence for DIS on ≤T2 lesions in the cord; C) positive CSF (isoelectric focusing evidence of oligoclonal bands and/or elevated IgG index)Source: Ann Neurol 2011;69:292-302