IMPORTANCE

Multiple sclerosis (MS) is an autoimmune-mediated neurodegenerative disease of the central nervous system characterized by inflammatory demyelination with axonal transection. MS affects an estimated 900 000 people in the US. MS typically presents in young adults (mean age of onset, 20-30 years) and can lead to physical disability, cognitive impairment, and decreased quality of life. This review summarizes current evidence regarding diagnosis and treatment of MS.

OBSERVATIONS

MS typically presents in young adults aged 20 to 30 years with unilateral optic neuritis, partial myelitis, sensory disturbances, or brainstem syndromes such as internuclear ophthalmoplegia developing over several days. The prevalence of MS worldwide ranges from 5 to 300 per 100 000 people and increases at higher latitudes. Overall life expectancy is less than in the general population (75.9 vs 83.4 years), and MS more commonly affects women (female to male sex distribution of nearly 3:1). Diagnosis is made based on a combination of signs and symptoms, radiographic findings (eg, magnetic resonance imaging [MRI] T2 lesions), and laboratory findings (eg, cerebrospinal fluid-specific oligoclonal bands), which are components of the 2017 McDonald Criteria. Nine classes of disease-modifying therapies (DMTs), with varying mechanisms of action and routes of administration, are available for relapsing-remitting MS, defined as relapses at onset with stable neurologic disability between episodes, and secondary progressive MS with activity, defined as steadily increasing neurologic disability following a relapsing course with evidence of ongoing inflammatory activity. These drugs include interferons, glatiramer acetate, teriflunomide, sphingosine 1-phosphate receptor modulators, fumarates, cladribine, and 3 types of monoclonal antibodies. One additional DMT, ocrelizumab, is approved for primary progressive MS. These DMTs reduce clinical relapses and MRI lesions (new T2 lesions, gadolinium-enhancing lesions). Efficacy rates of current DMTs, defined by reduction in annualized relapse rates compared with placebo or active comparators, range from 29%-68%. Adverse effects include infections, bradycardia, heart blocks, macular edema, infusion reactions, injection-site reactions, and secondary autoimmune adverse effects, such as autoimmune thyroid disease.

CONCLUSIONS AND RELEVANCE

MS is characterized by physical disability, cognitive impairment, and other symptoms that affect quality of life. Treatment with DMT can reduce the annual relapse rate by 29% to 68% compared with placebo or active comparator.