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PARIS -- Researchers here revealed key revisions to the McDonald criteria for diagnosing multiple sclerosis, chief among them the use of oligoclonal bands (OCBs) to make a speedier diagnosis as well as including both symptomatic and asymptomatic lesions as evidence of dissemination.

"The 2017 revisions further refine the well-established McDonald criteria and are based on new data," revision co-chair Jeffrey Cohen, MD, of the Cleveland Clinic, said during an oral session at the joint . "The appropriate application of the criteria is critical to avoid misdiagnosis, and fundamentally MS remains a clinical diagnosis, requiring the rigorous synthesis of imaging and laboratory data by a clinician with expertise in MS."

Though he didn't present a full evidence review as the revised criteria have just been accepted for publication, Cohen shared the five top-line revisions.

"Probably the one that's going to be the most controversial," he said, is the recommendation to use the presence of OCBs in cerebrospinal fluid (CSF) to make the diagnosis of MS in a patient with typical clinically isolated syndrome (CIS) who has clinical or MRI evidence of dissemination in space.

"This does not represent the demonstration of dissemination in time, but it in fact allows for substitution of dissemination in time," Cohen said.

The second biggest change is that now, both symptomatic and asymptomatic MRI lesions can be considered in determining dissemination in space and time, Cohen said. In the previous 2010 revision, symptomatic lesions couldn't be considered as MRI evidence of this diagnostic criteria.

Third, cortical lesions can be used to demonstrate dissemination in space, while previously only juxtacortical lesions could be used. Cohen warned that this recommendation should be interpreted carefully as the ability to detect "truly cortical MRI lesions is relatively limited."

Fourth, specific criteria for diagnosing primary progressive MS have not changed, aside from the lack of distinction between symptomatic and asymptomatic lesions and the fact that cortical lesions can be used.

Finally, the revised criteria recommend determining a provisional disease course as specified by Lublin et al at the time of diagnosis, and periodically re-evaluating it based on accumulated evidence.

Cohen said there were several proposals that weren't adopted because of a lack of evidence. While the 2016 MAGNIMS criteria increased the number of periventricular lesions from 1 to 3, the McDonald revision committee felt the "modest increase in specificity did not justify making the change."

The group also declined to include the presence of optic neuritis pathology in the revised criteria, but acknowledged that the condition is an "important manifestation of MS" and represents an "area of high priority for research."

These revisions to the McDonald criteria need to be validated in a range of other populations, including by ethnic group, age, comorbidities, and in a more general neurology practice, Cohen said. There's also a need for further development of MRI to provide better sensitivity and specificity for determining MS pathology, and a non-imaging biomarker to make the diagnosis of MS.

Jeremy Chataway, PhD, of University College London, who wasn't involved in the revision but provided commentary during the oral session, noted that it's important to make the diagnosis of MS faster but more accurately in this new era of strong anti-inflammatory therapeutic agents.

"The consequences can be profound," he said. "There are rare but serious side effects with our potent anti-inflammatory armamentarium: PML, Zoster, immune thrombocytopenic purpura, cardiac effects."

While MS diagnosis is faster now than ever before -- from two years down to six months, on average -- "we must not diagnose other conditions as MS," he said.

Regarding the use of OCBs in diagnosis, Chataway noted that there was a drift away from CSF testing over the last 5 to 10 years, but the need for specificity and accumulating evidence is turning back the tide.

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