MS's New Challenge: The McDonald Criteria 1 of 4

MS New Diagnostic Criteria

MS's New Challenge: The McDonald Criteria

Craig H. Smith, M.D.
Director, Swedish Medical Center
Multiple Sclerosis Center

An Antiquated Paradigm

Over the past 5 years there has been a virtual explosion in the knowledge regarding the pathophysiology and immunology of MS. Practicing neurologists have been confronted with new technologies to incorporate into the diagnostic workup of the patient with presumed MS. Folded into this thicket of information and powerful technologic tools is the bewildering morass of immunomodulatory therapies with conflicting claims of efficacy. Just when we thought that there was light at the end of the long tunnel of learning, a new diagnostic criterion has thrown seemingly more confusion into an already over-burdened arena of care. In this article we will review the new diagnostic criterion and how this integrates into our neurologic care of the MS patient. The new criteria, when closely examined, assist significantly in defining an early diagnostic approach to MS.

MS remains a clinical diagnosis; dependent on a detailed history, careful neurologic examination and a review of paraclinical evidence (MRI studies, cerebrospinal fluid analysis and evoked potential testing). The classical diagnostic criterion in MS, which is still applicable, is evidence of lesions in the central nervous system (CNS) disseminated in time and space. This means that more than one lesion has to involve more than one area of the nervous system. This involvement might occur in optic nerve, brain or spinal cord. Prior to the 1980's, confusion reigned regarding the diagnosis of this condition. Virtually no guidelines existed to help clinicians, and clinical trials were virtually unknown; not forcing establishment of accepted diagnostic standards. 

In 1982 a committee, established by the National MS Society, produced the Poser criteria¹ for use in clinical trials involving MS. The committee proposed four categories including clinically definite MS; laboratory (CSF) supported definite MS, probable MS (either clinically or laboratory supported) and possible MS. In 1982, MRI as a technology, was in its infancy - and was included as a paraclinical element along with urodynamic testing and evoked potentials. For twenty years we have utilized the Poser criteria despite a burgeoning science of imaging technology-integrating MRI into the diagnostic paradigms of MS. As a result, neurologists have been hampered by out-dated diagnostic paradigms strangling the utilization of advancing technologic tools. Clinical trials demanded a better set of criteria.

In July 2000, the International Panel on the Diagnosis of MS, chaired by W. Ian McDonald, FRCP (Royal College of Physicians, London), met in London to review the Poser criteria and to recommend change, where appropriate-including integration of MRI into the diagnostic process because of its ability to depict disease-related damaged areas, or lesions, in the brain and spinal cord.

The panelists developed step-by-step instructions to guide physicians toward diagnosing different forms of MS, including primary-progressive MS, which involves progressive disability from onset without the distinct attacks of the more common relapsing-remitting form of MS. For the first time, the panel also outlined steps to determine an MS diagnosis in a person who has only had one attack of symptoms. 

The new diagnostic criteria, published in the July 2001 issue of Annals of Neurology (published early online on April 2, 2001), were authored by Dr. McDonald and 15 other panel members. This new criteria is now also named after the committee chair; in this case it is called the "McDonald criteria" ². This was a true international effort, and the guidelines were designed by the committee to be used anywhere, irrespective of regional differences in healthcare resources or practices.