Probably the most implicitly used definition is clinical, and can be found in the McDonald criteria proposal.

McDonald criteria can be summarize in this table:

The McDonald criteria for the diagnosis of multiple sclerosis were revised in 2005 to clarify exactly what is meant by an "attack".

Currently the McDonald criteria are considered a clinical definition of MS.

The 2010 McDonald criteria are regarded as the gold standard for MS diagnosis.

Diagnostic criteria for multiple sclerosis: 2005 revisions to the McDonald Criteria.

Some other authors consider McDonald criteria as an attempt for a clinical definition and propose a pathological definition instead.

They observations were taken into account when McDonald criteria were published, and therefore they can be considered deprecated by the later.

The McDonald criteria are diagnostic criteria for multiple sclerosis (MS).

Therefore, when used as a definition, the McDonald criteria are defining MS just by exclusion of other diseases.

These criteria were later substituted by Poser criteria and McDonald criteria.

Among them, Poser criteria and McDonald criteria.

McDonald criteria have been shown to have a low sensitivity and specificity (with respect to the presence of lesions) in Asiatic populations.

Current McDonald criteria usually do not allow to stablish a diagnosis for definite MS before two clinical attacks have appeared.

They replaced the older Schumacker criteria, and now they are considered obsolete as McDonald criteria have superseded them.

The most common guidelines used for this are called the McDonald criteria, which define the symptoms of MS and how often they must occur in order to make a diagnosis.

In 2001, the International Panel on the Diagnosis of Multiple Sclerosis issued the McDonald criteria, a revision of the previous diagnostic procedures to detect MS, known as the Poser criteria.

Poser criteria introduced the CNS oligoclonal bands into the diagnosis criteria, while McDonald criteria focus on a demonstration with clinical, laboratory and radiologic data of the dissemination of MS lesions in time and space for non-invasive MS diagnosis.

"While maintaining the basic requirements of dissemination in time and space, the McDonald criteria provided specific guidelines for using findings on MRI and cerebrospinal fluid analysis to provide evidence of the second attack in those individuals who have had a single demyelinating episode and thereby confirm the diagnosis more quickly."