What is multiple sclerosis (MS)? In a nutshell, MS is an autoimmune disease that affects the nervous system. The disease destroys insulation around nerves, leaving scar tissue and the inability for nerve impulses to travel through the body with ease. Symptoms include numbness and tingling in the extremities, as well as vision problems, incontinence and a loss of cognitive ability. Women are at higher risk than men, and theories exist that individuals of Northern European ancestry are more prone to developing the disease.