Over the past four decades, the tools for diagnosing multiple sclerosis have changed as our understanding of the disease process and technological advances have developed.  Following the current diagnosis criteria, patients with early “silent” MS can be diagnosed much more quickly in order to begin disease-modifying therapy as soon as possible, which is recommended by the National MS Society.

Multiple sclerosis (MS) is an inflammatory, demyelinating autoimmune disease of the central nervous system. MS can present with a wide variety of symptoms, and in certain cases, making a diagnosis can be very challenging. Clinically, MS requires neurological problems associated with objective abnormalities (ie. brain lesions, O-bands in cerebrospinal fluid, etc) to be diagnosed.

In 1965, Schumacher et al. outlined the basic principles of MS diagnosis which are:
    •    Neurological examination which reveals objective abnormalities of central nervous system (CNS) function.
    •    History which indicates involvement of two or more parts of CNS.
    •    CNS disease which predominately reflects white matter involvement.
    •    Involvement of CNS which follows one of two patterns:
         - Two or more episodes, each lasting at least 24 hours and at least one month apart.
         - Slow or stepwise progression of signs and symptoms over at least 6 months.
    •    Patient aged 10 to 50 years old at onset.
    •    Signs and symptoms which cannot be better explained by other disease process.

The Schumacher criteria led to the development of the following designations, which although still broadly used have been updated with the advent of analysis of cerebrospinal fluid (CSF) by electrophoresis and the ability to detect clinically silent lesions through MRI scans.

    •    Clinically Definite MS - which was made if all the Schumacher criteria are fulfilled.
    •    Probable MS - which refers to Relapsing/Remitting MS (RRMS) symptoms where only one neurological symptom commonly associated with MS is found or if there is only a single attack and there was no better explanation for the symptoms.
    •    Possible MS - which refers to RRMS symptoms without documented signs or where the objective signs are insufficient to establish more than one site of CNS involvement.

In 1983, Poser et al. modified the criteria to incorporate laboratory studies in addition to clinical evaluation.  These laboratory studies, which include cerebrospinal fluid analysis, evoked potentials, and imaging studies, help the neurologist determine the existence and location of lesions.  It also provides the neurologist with additional paraclinical evidence that MS is present in the body.