Guidelines for MS diagnosis: McDonald criteria
Fact-checked by
Multiple sclerosis is an autoimmune disease caused by the immune system attacking parts of the central nervous system (CNS) — which includes the brain, spinal cord, and optic nerves. An early diagnosis of the disease is important but can be challenging. Clinicians may use something called the McDonald criteria to make a definitive MS diagnosis.
What are the McDonald criteria?
The McDonald criteria are a set of guidelines that incorporate clinical and laboratory evaluations, as well as magnetic resonance imaging (MRI) data, to establish an MS diagnosis.
The first version of the criteria was published in 2001 by an international team led by neurologist Ian McDonald. The criteria have since been extensively updated several times, most recently in 2017 revisions.
How are the McDonald criteria used to diagnose MS?
To fulfill a diagnosis of MS based on the 2017 McDonald criteria, an individual must have:
- evidence of CNS damage that is disseminating in space, or appearing in multiple regions of the nervous system.
- evidence of damage that is disseminating in time, or occurring at different points in time.
If the individual does not meet these two criteria, then the clinical case will be considered not MS.
Dissemination in space
Dissemination in space means that neurological damage is occurring in multiple parts of the CNS. Specifically, the 2017 criteria define dissemination in space as disease lesions in at least two of four regions in the nervous system. These regions include three areas of the brain (periventricular, juxtacortical or cortical, and infratentorial) and the spinal cord.
Notably, while lesions in the optic nerves are common in MS, the criteria for dissemination in space cannot be fulfilled with optic nerve lesions in a person with symptoms of optic neuritis, or inflammation in the optic nerves.
Dissemination in time
Similarly, dissemination in time means that neurological damage is happening at more than one point in time. This can be evidenced either by a second disease exacerbation, the appearance of new lesions on MRI scans, or by clear-cut evidence of brain damage that happened at different times — specifically, new inflammatory lesions alongside older lesions that are no longer actively inflamed.
A contrast agent called gadolinium can be used during an MRI to better distinguish active and inactive lesions. Gadolinium enhancing lesions represent areas of active inflammation.
Oligoclonal bands
Oligoclonal bands are antibodies (also called immunoglobulins) that are characteristically detected in the cerebrospinal fluid (CSF) — the fluid surrounding the brain and spinal cord — in people with MS.
The presence of these proteins is indicative of CNS inflammation and is an independent predictor of relapse in individuals with clinically isolated syndrome (CIS). Those with CIS experience a single episode of MS-like symptoms.
Thus, under the 2017 McDonald criteria, testing positive for oligoclonal bands can be sufficient to fulfill the criteria for dissemination in time, even if a patient only has evident damage from one time point.
| Clinical presentation | What else is needed to confirm an MS diagnosis? |
|---|---|
| Two or more relapses, plus evidence of damage in at least two CNS regions | Both criteria for dissemination in time and space have been fulfilled. A formal diagnosis of MS can be made without any additional data. |
| Two or more relapses, plus evidence of damage in only one part of the CNS | The criterion for dissemination in time has been met. Dissemination in space must be demonstrated by one of the following:
|
| One relapse, plus evidence of damage in two or more CNS regions | The criterion of dissemination in space has been fulfilled. Evidence of dissemination in time is needed and should be demonstrated via at least one of the following:
|
| One relapse and evidence of damage in one area of the CNS | Neither dissemination in time nor dissemination in space have been met.
For a definitive MS diagnosis, dissemination in time must be shown by one of the following:
Dissemination in space also must be demonstrated by one of the following:
|
| Insidious progression of neurological symptoms indicative of MS | A formal diagnosis of PPMS may be made if symptoms gradually progress for at least one year and if two of the following are met:
|
What does the updated version of the McDonald criteria mean for MS patients?
The updated 2017 version of the McDonald criteria, which follows a 2010 revision, does not invalidate an MS determination for those previously diagnosed based on older versions of these criteria.
The main goal of this new version was to simplify or clarify elements of the previous criteria. The updates are designed to facilitate earlier diagnoses in cases in which the disease was considered only “possible MS,” and to help improve diagnostic accuracy and avoid misdiagnosing MS.
2017 revisions to the McDonald criteria
Similar to the previous revision, the 2017 McDonald criteria continue to apply primarily to patients with CIS. The three main updates to the criteria, focused on typical CIS, were that:
- the presence of oligoclonal bands in the CSF can substitute for the requirement of demonstrating dissemination in time, enabling an MS diagnosis in patients meeting the criteria for dissemination in space.
- in addition to asymptomatic MRI lesions, symptomatic ones are now taken into account when determining dissemination in space or time — except for lesions in the optic nerve in a patient with optic neuritis symptoms.
- lesions in the cortical area of the brain, in addition to juxtacortical lesions, are now considered when determining MRI criteria for dissemination in space.
Relapsing MS and the McDonald criteria
Most people with the disease experience MS relapses, also called exacerbations or attacks. These are times of suddenly worsening symptoms that are accompanied by inflammation in the CNS, followed by remissions when symptoms ease.
A person who has experienced at least two clinical attacks, and has clear-cut evidence of damage in at least two distinct brain areas, can be definitively diagnosed with MS, as that individual fulfills requirements for both dissemination in space and time.
If a person has experienced at least two relapses but has objective evidence of damage in only one brain region, then that individual has fulfilled the criteria for dissemination in time, but not in space. Damage in another brain region — either demonstrated by a subsequent relapse implicating a different brain region, or by an MRI scan — must be detected before MS can formally be diagnosed.
Similarly, someone with lesions in two or more brain regions who experienced only one MS-like exacerbation fulfills the criteria for dissemination in space, but not in time. New damage occurring over time, evidenced by a new lesion on MRI scans or by another relapse, is needed for a formal diagnosis. Alternatively, testing positive for oligoclonal bands can be enough to fulfill the criteria for an MS diagnosis in such patients.
If a person has had one MS-like attack and has evidence of damage in one brain region, then that individual has not fulfilled the criteria for dissemination in space or in time. A formal diagnosis of MS cannot be made without clear evidence of further damage in other brain regions occurring over time.
Primary progressive MS and the McDonald criteria
Unlike the more common relapsing forms, primary progressive MS (PPMS) is not characterized by disease relapses. Instead, this disease type is defined by disability that gradually gets worse over time, starting from the onset of the disorder.
According to the 2017 McDonald criteria, PPMS may be formally diagnosed in people who experience worsening disability for at least one year (based on previous symptoms or ongoing observation), and who exhibit at least two of the following:
- at least one MS-like lesion in the brain
- at least two lesions in the spinal cord
- a positive test for oligoclonal bands in the CSF
Multiple Sclerosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
FAQs about McDonald criteria
Yes. The McDonald criteria are a formal set of guidelines that enable an accurate diagnosis of MS as early as possible. Depending on the clinical presentation of each patient, or the symptoms the person experiences, the criteria determine which additional tests should be performed before a formal diagnosis can be made. Therefore, using the criteria can allow MS to be diagnosed as quickly as possible.
Dissemination in time means that there is MS-like neurological damage that is occurring at multiple points in time. Similarly, dissemination in space means that the damage is affecting multiple parts of the brain and/or spinal cord. Under the McDonald criteria, only patients meeting both of these requirements can receive a formal MS diagnosis.
Relapses are important clinical factors that help establish a formal MS diagnosis. For example, tracking relapses can be useful for telling whether or not a person meets the criterion of dissemination in time: If a person has had at least two relapses, this is clear evidence of inflammatory brain damage happening at multiple points in time. The symptoms that appear during relapses also may indicate damage to different parts of the central nervous system, which can be used to fulfill the criterion of dissemination in space.
Optic neuritis refers to inflammation in the optic nerves, which transmit information from the eyeballs to the brain. According to the 2017 McDonald criteria, the optic nerves are not one of the regions that can be considered when determining whether or not a person with optic neuritis fulfills the criterion of dissemination in space.
The 2017 updates to the McDonald criteria aimed to simplify and clarify elements of older versions of the criteria, to help facilitate an earlier diagnosis of MS. A key update was the inclusion of oligoclonal bands in the cerebrospinal fluid as a possible surrogate of dissemination in time. That inclusion takes into account both symptomatic and asymptomatic lesions when determining dissemination in space or time. The updated version also counts lesions in the brain’s cortex, in addition to juxtacortical ones, when assessing for dissemination in space.
Related Articles
