Medical organizations have created diagnostic criteria to ease and standardize the diagnostic process especially in the first stages of the disease. Schumacher criteria were the first internationally recognized criteria for diagnosis, and introduced concepts still in use, as CDMS (Clinically definite MS).

Since then, other diagnosis criteria have been proposed. Among them, Poser criteria

Poser criteria

Poser criteria are diagnostic criteria for multiple sclerosis . They replaced the older Schumacker criteria, and now they are considered obsolete as McDonald criteria have superseded them...

 and McDonald criteria

McDonald criteria

The McDonald criteria are diagnostic criteria for multiple sclerosis . These criteria are named after neurologist W. Ian McDonald. In April 2001 an international panel in association with the National Multiple Sclerosis Society of America recommended revised diagnostic criteria for MS...

.

Sometimes it has been stated that the only proved diagnosis of MS is autopsy, or occasionally biopsy, where lesions typical of MS can be detected through histopathological techniques, Nevertheless, small lesions are invisible under MRI. Therefore including clinical observations still yield a more accurate MS diagnosis than MRI alone.

Schumacher criteria

To get a diagnosis of CDMS a patient must show the following:

1. Clinical signs of a problem in the CNS
2. Evidence of two or more areas of CNS involvement
3. Evidence of white matter involvement
4. One of these: Two or more relapses (each lasting ≥ 24 hr and separated by at least 1 month) or progression (slow or stepwise)
5. Patient should be between 10 and 50 yr old at time of examination
6. No better explanation for patient’s symptoms and signs

The last condition, no better explanation for symptoms, has been heavily criticised, but it has been preserved and it is currently included in the new McDonalds criteria in the form that "no better explanation should exist for MRI observations"

Poser criteria

Poser criteria can be summarized in this table:

Any of the five conclusions have subpossibilities. Here a table is shown with each one of them:

Clinical Presentation	Additional Data Needed
CDMS	* Two or more attacks (relapses)	Two clinical evidence One clinical and one paraclinical evidence
LSDMS	* At least one attack and oligoclonal band Oligoclonal band Oligoclonal bands are bands of immunoglobulins that are seen when a patient's blood serum, gained from blood plasma, or cerebrospinal fluid is analyzed.... s	Two attacks and one evidence (clinical or paraclinical) One attack and two clinical evidences One attack, one clinical and one paraclinical evidences
CPMS	* At least one attack	Two attacks and one clinical evidence One attack and two clinical evidences One attack, one clinical and one paraclinical evidences
LSPMS	* Two attacks	No more evidence is required

If none of these requirements is accomplished, the diagnosis is "No MS", meaning that there is not enough clinical evidence to support a clinical diagnosis of MS.

Barkoff/Tintoré criteria

Barkoff criteria, , later modified by Tintoré were an early attempt to use MRI to diagnose MS.

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

McDonald criteria

McDonald criteria can be summarize in this table:

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
* 1 attack * 2 or more objective clinical lesions	Dissemination in time, demonstrated by: * MRI * or second clinical attack
* 1 attack * 1 objective clinical lesion (monosymptomatic presentation)	Dissemination in space demonstrated by: * MRI * or positive CSF and 2 or more MRI lesions consistent with MS and Dissemination in time demonstrated by: * MRI * or second clinical attack
Insidious neurological progression suggestive of MS (primary progressive MS)	One year of disease progression (retrospectively or prospectively determined) and Two of the following: a. Positive brain MRI (nine T2 lesions or four or more T2 lesions with positive VEP) b. Positive spinal cord MRI (two focal T2 lesions) c. Positive CSF