The McDonald Criteria

Don't worry this has nothing to do with burgers or anyone named Ronald.

In actual fact this is the criteria the Consultants, Doctors and medical professionals will use to diagnose someone with Multiple Sclerosis.

I am sure many of us have gone through or may well be going through the process of diagnosis. It can be a lengthy process to actually confirm a diagnosis. As a patient this is frustrating, as we just want to know what is wrong with us!

Medical professional don't just confirm a diagnosis of Multiple Sclerosis based on one test, there are a number of tests that need and/or can be done to confirm MS.

As frustrating as this is, it is probably the best approach as MS is a condition that we currently don't have a cure for, nor do we know why it occurs. Of course there is conjecture and a number of possible contributing elements that we discuss in other parts of this website, but as a fact; we don't know the exact causes of MS. So, you can appreciate that when a medical professional confirms a diagnosis, they have to be 100% sure.



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The McDonald criteria use MRI scans evidence extensively to confirm an MS diagnosis, together with evidence from a lumbar puncture in some instances. They allow for an MS diagnosis to be made on the basis of one relapse (a sudden episode of symptoms or disability) given the right MRI evidence.

An attack or relapse must last for at least 24 hours, must be a neurological occurrence consistent multiple sclerosis, and that there must be at least 30 days between the onset of the first attacks and any subsequent attack - whether seen clinically or just on MRI - to count as two separate MS events. However, this can differ from patient to patient, depending on progression of symptoms.

The McDonald criteria were last revised in 2010, due to criticisms of the 2006 model, so it is an up to date and current measure. For those interested, the newer additions are highlighted. The new criteria also take into account non-Western Caucasian populations.

If you are to think of the criteria in two parts; you need a clinical presentation plus additional data.

Here is a table explaining the McDonald Criteria:


Clinical Presentation Additional Data Needed
* 2 or more attacks (relapses)
* 2 or more objective clinical lesions
None; clinical evidence will suffice (additional evidence desirable but must be consistent with MS)
* 2 or more attacks
* 1 objective clinical lesion
Dissemination in space, demonstrated by:
* MRI
* or a positive CSF and 2 or more MRI lesions consistent with MS
* or further clinical attack involving different site.
New criteria: Dissemination in Space (DIS) can be demonstrated by the presence of 1 or more T2 lesions in at least 2 of 4 of the following areas of the CNS: Periventricular, Juxtacortical, Infratentorial, or Spinal Cord.
* 1 attack
* 2 or more objective clinical lesions
Dissemination in time (DIT), demonstrated by:
* MRI
* or second clinical attack
New criteria: No longer a need to have separate MRIs run; Dissemination in time, demonstrated by: Simultaneous presence of asymptomatic gadolinium-enhancing and nonenhancing lesions at any time; or A new T2 and/or gadolinium-enhancing lesion(s) on follow-up MRI, irrespective of its timing with reference to a baseline scan; or Await a second clinical attack. [This allows for quicker diagnosis without sacrificing specificity, while improving sensitivity.]
* 1 attack
* 1 objective clinical lesion (clinically isolated syndrome)
New criteria: Dissemination in space and time, demonstrated by:
For DIS: 1 or more T2 lesion in at least 2 of 4 MS-typical regions of the CNS (periventricular, juxtacortical, infratentorial, or spinal cord); or Await a second clinical attack implicating a different CNS site; and For DIT: Simultaneous presence of asymptomatic gadolinium-enhancing and nonenhancing lesions at any time; or A new T2 and/or gadolinium-enhancing lesion(s) on follow-up MRI, irrespective of its timing with reference to a baseline scan; or Await a second clinical attack.
Insidious neurological progression suggestive of MS (primary progressive MS) New criteria: One year of disease progression (retrospectively or prospectively determined) and two or three of the following:

1. Evidence for DIS in the brain based on 1 or more T2 lesions in the MS-characteristic (periventricular, juxtacortical, or infratentorial) regions

2. Evidence for DIS in the spinal cord based on 2 or more T2 lesions in the cord

3. Positive CSF (isoelectric focusing evidence of oligoclonal bands and/or elevated IgG index)

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