Beginner's Guide to MS: Multiple Sclerosis Diagnostic Criteria, The History
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.
The Poser criteria and diagnostic categories are:
- Clinically definite MS
- 2 attacks and clinical evidence of 2 separate lesions
- 2 attacks, clinical evidence of one lesion and paraclinical evidence of another separate lesion
- Laboratory supported Definite MS - 2 attacks, either clinical or paraclinical evidence of 1 lesion, and cerebrospinal fluid (CSF) immunologic abnormalities
- 1 attack, clinical evidence of 2 separate lesions & CSF abnormalities
- 1 attack, clinical evidence of 1 lesion and paraclinical evidence of another separate lesion, and CSF abnormalities
- Clinically probable MS - 2 attacks and clinical evidence of 1 lesion
- 1 attack and clinical evidence of 2 separate lesions
- 1 attack, clinical evidence of 1 lesion, and paraclinical evidence of another separate lesion
- Laboratory supported probable MS
- 2 attacks and CSF abnormalities
In 2001, the International Panel on the Diagnosis of Multiple Sclerosis (headed by McDonald) updated the diagnosis criteria to incorporate a set of standardized MRI criteria into the diagnostic process. The result was the use of MRI data to support evidence of demyelination and dissemination of space. This allows a person to be diagnosed more quickly, without waiting for a second clinical event.
This has allowed for new diagnostic category for persons who have experienced only one relapse (or exacerbation) of MS-like symptoms, a Clinically-Isolated Syndrome (CIS). A person with CIS may or may not go on to develop MS which raises some controversy and confusion to the diagnosis and treatment of MS.
Finally in 2005, the McDonald criteria was revised to help demonstrate demyelination and dissemination of time, to clarify the use of spinal cord lesions, and to simplify diagnosis of primary progressive disease. The 2005 revisions were designed to simplify and speed diagnosis, while maintaining adequate sensitivity and specificity.
The revised criteria for diagnosis of MS include the following:
- At least two attacks with objective clinical evidence of at least two lesions;
- At least two attacks with objective clinical evidence of one lesion plus dissemination in space shown on MRI, or two or more MRI lesions consistent with MS plus positive CSF finding or second clinical attack;
- One attack with objective clinical evidence of at least two lesions plus dissemination in time on MRI or second clinical attack;
- One attack with objective clinical evidence of one lesion, plus dissemination in space shown on MRI, or two or more MRI lesions consistent with MS plus positive CSF finding and dissemination in time shown on MRI or second clinical attack;
- Insidious neurologic progression suggestive of MS plus one year of disease progression determined retrospectively or prospectively and two of the following: positive brain MRI result (nine T2 lesions or at least four T2 lesions with positive Visual Evoked Potential), positive spinal cord MRI result with two focal T2 lesions, and positive CSF findings.