Current Series: Multiple Sclerosis: A Disease of an Immune System Gone Awry

Clyde E. Markowitz, MD: The diagnosis of multiple sclerosis [MS] is usually a given by a set of criteria. We call this criteria the McDonald criteria. These criteria have been set up over the years to allow us to include not just the clinical manifestations of MS but also other supporting data, including MRI [magnetic resonance imaging], spinal fluid, and things like that.

When we talk about diagnosis, we are looking to make it as early as possible. To accomplish that we will look at patients when they present with their first event. That first event might be something like an optic neuritis or maybe a transverse myelitis or something like that, and at that point you’ll do the workup. The workup may include an MRI scan, and it may include spinal fluid. You may define this person at this point as having a clinically isolated syndrome.

When they get the MRI scan, and you see that there are a number of lesions in the brain, you might be concerned that this has been going on—that these are more than 1 event—even though clinically, they presented with 1 event. But their manifestations on brain MRI may have told us that there are a number of things that have been going on silently. The McDonald criteria were developed with the idea that we can use the MRI scan to give us a piece of information that patients did not experience clinically but where there was subclinical activity. If we see multiple lesions separated in space and time, that is what is required to make a diagnosis by the McDonald criteria.

This iteration has evolved over the last couple of decades. We’ve had criteria in 2001, 2005, and all along the route; and now, in 2017, we have the most recent version. What it has allowed us to do is make a diagnosis as early as possible. You could make a diagnosis of clinically isolated syndrome patients after 1 event if they meet certain criteria on MRI and/or spinal fluid. If they have a number of lesions, with some that are active and some that are not active, that gives us a time component because we know that activity on an MRI scan may last only about a month to 6 weeks.

If they don’t have the activity metric, but they have space—meaning you see multiple lesions, but they’ve had 1 event—you now can utilize the spinal fluid analysis if they have positive oligoclonal bands. That will fit the criteria of time to allow us to be able to make a diagnosis.

There are other changes, including things such as cortical lesions, that can now be used to allow us to make a diagnosis. In addition to that, you can look at the MRI scan and see that there are lesions that are symptomatic of the event that’s happening at this time. You can now use that symptomatic lesion as a possible diagnostic criterion.

Patricia K. Coyle, MD: The most recent 2017 revised McDonald diagnostic criteria have not significantly changed my practice at all. I would just say the following: I originally didn’t like the diagnostic criteria. Early on, I thought they were too complex, but I like them now. I think they have, in the number of revisions, really gotten much better. I think everybody should be using the 2017 McDonald diagnostic criteria if they’re making a diagnosis of either relapsing or primary-progressive MS. I think there should be a comment on whether they meet those criteria.

What we really need are radiologists and neuroradiologists to buy into that. If we’re doing an MRI scan for a potential diagnosis of MS, I think they need to be referring to the McDonald diagnostic criteria. There are 2 ways by the diagnostic criteria to make a diagnosis of MS, even though there has been only 1 attack or clinically isolated syndrome: if you meet the MRI dissemination in space and time, or if you meet the MRI dissemination in space, and they have positive CSF [cerebrospinal fluid]-specific oligoclonal bands. In those 2 instances, even though there has been only 1 attack, I will say that this person meets the formal criteria for MS. That’s probably the most popular way that I’m currently using them.