Practice parameter: The usefulness of evoked potentials in identifying clinically silent lesions in patients with suspected multiple sclerosis (an evidence-based review)

Abstract

The Quality Standards Subcommittee of the American Academy of Neurology (AAN) is charged with developing practice parameters for neurologists for diagnostic procedures, treatment modalities, and clinical disorders. The selection of topics for which practice parameters are used is based on prevalence, frequency of use, economic impact, membership involvement, controversy, urgency, external constraints, and resources required. This article addresses the usefulness of evoked potentials (EPs) in identifying clinically silent lesions in patients with suspected MS. The diagnosis of MS remains primarily clinical, requiring evidence of white matter lesions disseminated in space and time.1,2 Some patients with suspected MS not fulfilling clinical dissemination criteria (MS suspects) have abnormal EPs that identify clinically unsuspected lesions.3,4 Current diagnostic criteria allow MS suspects to be reclassified into definite MS categories if EPs identify clinically silent lesions.2,5 The identification of clinically unsuspected lesions is one major reason clinicians use EPs in MS suspects.4,6 Presumably, MS suspects with EP-identified clinically silent lesions are more likely to have MS and are at higher risk for developing MS-related disabilities. Accurately identifying these high-risk patients will become increasingly important if early therapies are demonstrated to be effective in preventing or delaying disability in patients with MS. To determine the effectiveness of EP-identified silent lesions in diagnosing MS, we performed a systematic review and analysis of the literature. Based on this review we propose practice parameters for the use of EPs in patients with suspected MS. Confirmation of the ability of EP-identified clinically silent lesions to diagnose MS requires a comparison with an independently verifiable gold standard.7 Potential gold standards include pathologic confirmation of MS lesions, brain MRI, or the eventual development of clinically definite MS (CDMS). Pathologic confirmation in MS suspects is not usually practical given the …