Diagnostic Criteria for Multiple Sclerosis (McDonald Criteria)

The National MS Society of America convened an international panel chaired by Professor W. Ian McDonald to update the Poser Criteria for the diagnosis of MS and in April 2001 recommended the following criteria which makes use of MRI imaging in making diagnostic conclusions:

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 by 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)	Positive CSF and Dissemination in space demonstrated by: MRI evidence of 9 or more T2 brain lesions or 2 or more spinal cord lesions or 4-8 brain and 1 spinal cord lesion or positive VEP with 4-8 MRI lesions or positive VEP with <4 brain lesions plus 1 spinal cord lesion and Dissemination in time demonstrated by: MRI or continued progression for 1 year

What Is An Attack?

Neurological disturbance of kind seen in MS
Subjective report or objective observation
24 hours duration, minimum
Excludes pseudoattacks, single paroxysmal episodes

Determining Time Between Attacks

30 days between onset of event 1 and onset of event 2

How Is "Abnormality" In Paraclinical Tests Determined?

Magnetic resonance imaging (MRI) Three out of four:

1 Gd-enhancing or 9 T2 hyperintense lesions if no Gd-enhancing lesion
1 or more infratentorial lesions
1 or more juxtacortical lesions
3 or more periventricular lesions

(1 spinal cord lesion = 1 brain lesion)

Cerebrospinal fluid (CSF)

Oligoclonal IgG bands in CSF (and not serum)
or elevated IgG index

Evoked potentials (EP)

Delayed but well-preserved wave form

What Provides MRI Evidence Of Dissemination In Time?

A Gd-enhancing lesion demonstrated in a scan done at least 3 months following onset of clinical attack at a site different from attack,
or
In absence of Gd-enhancing lesions at 3 month scan, follow-up scan after an additional 3 months showing Gd-lesion or new T2 lesion.

Ongoing research

Research now looks at neuroprotection, repair and recovery mechanisms in the brain as well as the process of CNS damage. The new treatments have shown promise in the short term but the important questions are all long term, so long term outcomes are essential in evaluating the cost effectiveness of current and future therapies. The genetic predisposition, geographical distribution and potential trigger mechanism for the disease are all areas of current research.