The revised 2017 diagnostic criteria for multiple sclerosis
The last update to the McDonald criteria took place in 2010. The same year that the Affordable Care Act was passed, the year the H1N1 pandemic ended, and the year of the Deepwater Horizon Oil spill. And since that time, we’ve made incredible medical progress, both in the fields of diagnostics and therapeutics. In multiple sclerosis in particular, we’ve added several new drugs, including the first ever, highly effective FDA-approved therapy for primary progressive MS: Ocrelizumab. But, let’s just take a step back. Most of these improvements with time are treatment related. Diagnostic criteria shouldn’t have to change all that much right?
Why did we need updated diagnostic criteria for multiple sclerosis? Well, a couple of reasons. And all of them are helpful in making an earlier diagnosis, permitting earlier intervention with disease-modifying therapies.
Misdiagnosis. MS is a heterogeneous clinical condition, with various initial presentations, imaging findings, and clinical courses. No single test is 100% sensitive or specific. Features on MRI, which were used in the 2010 McDonald criteria, were non-specific, and can be seen in small vessel ischemic disease or prior strokes, migraines, Lyme disease, sarcoidosis, and other inflammatory conditions. Granted, the 2010 McDonald criteria were not designed to differentiate MS from these other conditions, they were designed to identify MS in patients with clinically isolated syndrome when these other conditions were less likely. Bottom line here: The MRI is non-specific unless you’ve incorporated a variety of pertinent clinical elements and the lesions are absolutely characteristic of MS. Say the patient is a 19-year-old girl with a history of 1 week of vision loss from high school, who now has some leg weakness and a small circumscribed, enhancing thoracic lesion. That sounds characteristic for MS. Without a classic story or classic imaging, more data is necessary.
Other testing. Besides the history and the physical exam, which you also use in making the diagnosis of MS regardless of the McDonald criteria—say the patient has worsening of prior symptoms in the heat, consistent with Uthoff’s phenomenon, that’s consistent with a demyelinating disorder—besides the history and the exam, how often are you getting the LP to look for oligoclonal bands? Like every time! And yet, CSF testing is not part of the 2010 criteria for relapsing remitting MS. So in 2017, the expert panel has amended this criterion, knowing that the presence of oligoclonal bands in a patient with clinically isolated syndrome is highly predictive of a subsequent attack. OCBs can be used as a substitute for the dissemination in time criteria. So, you can have RRMS if you have a single attack with 2 or more lesions and OCBs. This change is huge because it permits earlier diagnosis and allows for earlier treatment in patients who are at a high risk of recurrent attacks.
What counts as dissemination in space? So here’s something you might not have remembered from the 2010 McDonald criteria. If a patient
presented with an acute symptomatic brainstem or spinal cord lesion, this lesion could not be counted among the 2 lesions disseminated in space. Like a patient who has a whomping old non-enhancing periventricular lesion and a new transverse myelitis with a new enhancing thoracic lesion? That would not fulfill the 2010 McDonald criteria. But, now it does. Say that patient also had CSF testing at the time of their transverse myelitis, and had 3 oligoclonal bands? Wouldn’t matter, from 2010 to 2017, the patient still wouldn’t have MS. But now, those bands would be sufficient to diagnose the patient with MS even if their thoracic lesion didn’t enhance. And each of these features—the locations of those two lesions and the 3 bands—you know they are all predictive of a subsequent attack. Yet, they were previously insufficient to make the diagnosis.
Now, what about cortical lesions? With advances in neuroimaging, MRIs with greater magnet strength, it’s easier for us to pick up on smaller lesions. And we’ve learned that patients with MS have cortical as well as juxtacortical lesions. But cortical lesions didn’t matter in 2010. You could have a cortical lesion and an enhancing periventricular lesion—and it wouldn’t be MS. But now, if you see a cortical lesion, it counts just like a juxtacortical lesion, and that patient who has the non-enhancing cortical lesion and an enhancing periventricular lesion, this confirms dissemination in time and space. And you’ve made your diagnosis.
Lastly, is there an update to the criteria for Primary Progressive MS? Yes. But it’s a small one. In 2010, symptomatic brainstem or spinal cord lesions did not count towards the dissemination in time or space criteria—just as they didn’t count in RRMS. In 2017, now they do. So to make the diagnosis of primary progressive MS, you need only 1 year of progressive symptoms with 2 of the 3 following criteria: oligoclonal bands, 2 or more lesions of the spinal cord, or 1 or more lesion in the brain (either periventricular, cortical/juxtacortical, or infratentorial).
- CSF oligoclonal band testing can be used in lieu of the dissemination in time criterion.
- For RRMS and PPMS, the enhancing brainstem or spinal cord lesion can NOW be counted toward dissemination in time and space.
And a few other subtle things. So take a listen to the full length episode. It’s not even 10 minutes long.
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- Thompson AJ, Banwell BL, Barkhof F, Carroll WM, Coetzee T, Comi G, Correale J, Fazekas F, Filippi M, Freedman MS, Fujihara K, Galetta SL, Hartung HP, Kappos L, Lublin FD, Marrie RA, Miller AE, Miller DH, Montalban X, Mowry EM, Sorensen PS, Tintore M, Traboulsee AL, Trojano M, Uitdehaag BMJ, Vukusic S, Waubant E, Weinshenker BG, Reingold SC and Cohen JA. Diagnosis of multiple sclerosis: 2017 revisions of the McDonald criteria. The Lancet Neurology. 2017.