Introduction and Epidemiology¹ – MS is a CNS inflammatory disease of unknown etiology (thought to be autoimmune) that is characterized by areas of demyelination that are disseminated in time and space. US prevalence is ≈400,000, ranging from 40 to 220/100,000 with ♀:♂ = 2:1 and Caucasian>Asian>African American. Mean onset is ≈30 years of age. Incidence and death rates are higher in the northern latitudes, although this differential appears to be decreasing. An important factor appears to be where one lives prior to 15 years of age.

Diagnosis and Clinical Features – Definite MS has been classically defined as ≥2 attacks, separated by ≥1 month, with clinical, imaging, or laboratory evidence (e.g., ↑ CSF protein with oligoclonal bands on electrophoresis and delayed visual evoked potential [VEP]/somatosensory evoked potential [SSEP] latencies) of ≥2 lesions.² Each attack lasts >24 hours. Ovoid plaques that are bright on T2 MRI are typically found in the periventricular white matter, cortical-subcortical junction, brainstem, and/or cerebellum. Corpus callosum lesions are relatively specific for MS. In 2005, revisions were made to the McDonald criteria for the diagnosis of MS (see Table 19-1).³