Multiple sclerosis, McDonald Diagnostic Criteria
The original 2001 McDonald Diagnostic Criteria--a mainstay for diagnosing multiple sclerosis (MS)--have been modified by an international consensus panel. The panel, chaired by Chris H. Polman, MD, PhD, professor of neurology at the Free University Medical Center in Amsterdam, based its recommendations on several scientific studies of the 2001 criteria. The revisions are being enacted to better streamline diagnosis without compromising sensitivity and specificity.
According to panel member Jerry S. Wolinsky, MD, director of the Multiple Sclerosis Research Center and the Magnetic Resonance Imaging Analysis Center at the University of Texas Health Sciences Center in Houston, "a major clinical change that is not trivial for primary progressive MS is that you no longer have to show cerebrospinal fluid abnormalities." This modification is rooted in recent findings that approximately 20% of patients in whom primary progressive MS is diagnosed do not have markers for MS in cerebrospinal fluid (CSF).
Other important changes concern demonstration of dissemination of the disease process in time and space. Guidelines for use of contrast MRI to determine dissemination in time and space were first introduced in the 2001 McDonald Diagnostic Criteria.
According to the 2005 update, the determinant of progression in time is either detection of a gadolinium-enhancing lesion at least 3 months after the initial event at a site different from that of the original event, or detection of a new T2 lesion on an MRI scan performed at any time compared with a reference scan performed at least 30 days after the initial event. Dissemination in time also can be demonstrated by occurrence of a second clinical attack.
Dissemination in space requires that 3 of the 4 following conditions are satisfied on MRI:
• Presence of 1 gadolinium-enhancing lesion or 9 T2 hyperintense lesions in the absence of a gadolinium-enhancing lesion.
• Presence of at least 1 brain infratentorial or cord lesion. (Importantly, a spinal cord lesion can now be considered equivalent to a brain infratentorial lesion.)
• Presence of at least 1 juxtacortical lesion.
• Presence of 3 or more periventricular lesions.
An outline of the revisions is as follows:
• An MS diagnosis can be made without further diagnostic workup if 2 attacks have occurred and are accompanied by objective clinical evidence of 2 or more lesions.
• If 2 attacks have occurred in the presence of objective clinical evidence of 1 lesion, dissemination in space must be demonstrated by MRI or by the detection on an MRI scan of 2 additional lesions consistent with MS, accompanied by CSF positivity for MS (defined as presence of oligoclonal IgG bands or elevated IgG index). Clinicians also have the alternative of waiting for another clinical attack focused at another site.
• If 1 attack occurs and objective clinical evidence of 2 or more lesions exists, dissemination in time must be demonstrated by MRI or the occurrence of a second clinical attack.
• If 1 attack occurs in the presence of objective clinical evidence of 1 lesion, dissemination in space is required, demonstrated by MRI or the detection on MRI of 2 additional lesions accompanied by CSF positivity for MS and demonstration of dissemination in time by MRI or occurrence of a second clinical attack.
• If clinical evidence demonstrates 1 or more lesions in the absence of clinical attacks, the clinician needs to determine disease progression (retrospectively or prospectively) over the course of the year and demonstrate 2 of the following 3 conditions:
• Brain MRI scan of 9 T2 lesions or 4 or more T2 lesions with positive visually evoked potentials (defined as a delayed but preserved waveform).
• Presence on spinal cord MRI scan of 2 or more focal T2 lesions.
• Positive CSF.
The consensus panel statement appears in the December 2005 issue of Annals of Neurology (Polman CH, Reingold SC, Edan G, et al. Diagnostic criteria for multiple sclerosis: 2005 revisions to the "McDonald Criteria." Ann Neurol. 2005:58:840-846). A tipsheet from the National Multiple Sclerosis Society is available online at www.nationalmssociety.org/pdf/forpros/dx_ tipsheet.pdf. *