Definitions of the strength of the recommendations (A, B, C, U) and classification of the evidence (Class I through Class IV) are provided at the end of the "Major Recommendations" field.
Recommendations
- Magnetic resonance imaging (MRI) changes seen in multiple sclerosis (MS) are known to be nonspecific (refer to Table 2, entitled "Diagnostic Consideration in Patients with Suspected MS and/or MRI White Matter Abnormalities" in the original guideline document). Therefore, the information derived from imaging investigations must always be considered in the context of the specific clinical situation presented by an individual patient. As a result, the following recommendations are predicated on the exclusion, at baseline, of appropriate alternative conditions that can mimic MS or can mimic the radiographic findings seen in MS.
- On the basis of consistent Class I, II, and III evidence, in patients with clinically isolated syndrome (CIS), the finding of three or more white matter lesions on a T2-weighted MRI scan is a very sensitive predictor (>80%) of the subsequent development of clinically definite MS (CDMS) within the next 7 to 10 years (Type A recommendation). It is possible that the presence of even a smaller number of white matter lesions (e.g., one to three) may be equally predictive of future MS although this relationship requires better clarification.
- The presence of two or more gadolinium (Gd)-enhancing lesions at baseline is highly predictive of the future development of clinically definite MS (Type B recommendation).
- The appearance of new T2 lesions or new gadolinium enhancement 3 or more months after a clinically isolated demyelinating episode (and after a baseline MRI assessment) is highly predictive of the subsequent development of clinically definite MS in the near term (Type A recommendation).
- The probability of making a diagnosis other than MS in patients with clinically isolated syndrome with any of the above MRI abnormalities is quite low, once alternative diagnoses that can mimic MS or can mimic the radiographic findings of MS have been excluded (Type A recommendation).
- The MRI features helpful in the diagnosis of primary progressive MS (PPMS) cannot be determined from the existing evidence (Type U recommendation).
Definitions:
Rating of Recommendation
A = Established as useful/predictive or not useful/predictive for the given condition in the specified population.
B = Probably useful/predictive or not useful/predictive for the given condition in the specified population.
C = Possibly useful/predictive or not useful/predictive for the given condition in the specified population.
U = Data inadequate or conflicting. Given current knowledge, test/predictor is unproven
Rating of Diagnostic Article
Class I: Evidence provided by a prospective study in a broad spectrum of persons with the suspected condition, using a "gold standard" for case definition, where test is applied in a blinded evaluation, and enabling the assessment of appropriate tests of diagnostic accuracy. In addition, there must be adequate accounting for dropouts with numbers sufficiently low to have minimal potential for bias.
Class II: Evidence provided by a prospective study of a narrow spectrum of persons with the suspected condition, or a well-designed retrospective study of a broad spectrum of persons with an established condition (by "gold standard") compared to a broad spectrum of controls, where test is applied in a blinded evaluation, and enabling the assessment of appropriate tests of diagnostic accuracy.
Class III: Evidence provided by a retrospective study where either persons with the established condition or controls are of a narrow spectrum, and where test is applied in a blinded evaluation.
Class IV: Any design where test is not applied in blinded evaluation OR evidence provided by expert opinion alone or in descriptive case series (without controls).