Prognosis of Multiple Sclerosis: Variable. Ranging from mild to very serious, depending on exactly which nerves are attacked. Average survival is 35 years after diagnosis. A rare form of acute MS can be fatal quickly. Complications of Multiple Sclerosis: see complications of Multiple Sclerosis Prognosis of Multiple Sclerosis: The cause of MS remains elusive, but most people with MS have a normal life expectancy. The vast majority of MS patients are mildly affected, but in the worst cases, MS can render a person unable to write, speak, or walk. (Source: excerpt from NINDS Multiple Sclerosis Information Page: NINDS) ... Most commonly, damage to the central nervous system occurs intermittently, allowing a person to lead a fairly normal life. At the other extreme, the symptoms may become constant, resulting in a progressive disease with possible blindness, paralysis, and premature death.