Multiple sclerosis (MS) is a chronic, immune-mediated disease in which the body's immune system attacks the myelin sheath that surrounds nerve fibers in the brain and spinal cord. This demyelination disrupts nerve signals and leads to a wide range of symptoms, including fatigue, numbness, weakness, visual disturbances, coordination problems, and in some cases cognitive changes. MS can present in relapsing-remitting, secondary-progressive, or primary-progressive forms, each with different patterns of disability progression. Although treatments such as disease-modifying therapies can slow progression and reduce relapses, MS remains a serious condition with variable prognosis. From an insurance perspective, multiple sclerosis significantly affects morbidity and mortality assumptions, especially as disability advances or complications arise.

In underwriting, multiple sclerosis is treated as a major impairment that requires detailed medical documentation. Underwriters look for diagnosis date, type of MS, treatment regimen, MRI findings, relapse frequency, current level of functioning, and ability to perform activities of daily living. Early-stage, well-controlled cases with minimal disability may be insurable with ratings, while advanced cases often lead to postponement or decline, particularly for disability or long-term care coverage. Advisors working with clients who have MS gather neurologist reports and functional assessments to shop the case with carriers that are more experienced with neurological impairments. In conversations with clients, producers emphasize that full disclosure and realistic expectations are essential, and they sometimes pivot to guaranteed-issue or simplified-issue options when traditional underwriting is not feasible. Ongoing changes in MS treatment protocols and outcomes make it an area where underwriting guidelines are periodically updated.