Types of Multiple Sclerosis
People with Multiple Sclerosis (MS) can typically experience one of four
disease courses, each of which might be mild, moderate, or severe.
People with this type of MS experience clearly defined attacks of worsening
neurologic function. These attacks—which are called relapses, flare-ups,
or exacerbations —are followed by partial or complete recovery periods
(remissions), during which no disease progression occurs. Approximately
85% of people are initially diagnosed with relapsing-remitting MS.
This disease course is characterized by slowly worsening neurologic function
from the beginning—with no distinct relapses or remissions. The
rate of progression may vary over time, with occasional plateaus and temporary
minor improvements. Approximately 10% of people are diagnosed with primary-progressive MS.
Following an initial period of relapsing-remitting MS, many people develop
a secondary-progressive disease course in which the disease worsens more
steadily, with or without occasional flare-ups, minor recoveries (remissions),
or plateaus. Before the disease-modifying medications became available,
approximately 50% of people with relapsing-remitting MS developed this
form of the disease within 10 years. Long-term data are not yet available
to determine if treatment significantly delays this transition.
In this relatively rare course of MS (5%), people experience steadily worsening
disease from the beginning, but with clear attacks of worsening neurologic
function along the way. They may or may not experience some recovery following
these relapses, but the disease continues to progress without remissions.
Since no two people have exactly the same experience of MS, the disease
course may look very different from one person to another. And, it may
not always be clear to the physician—at least right away—which
course a person is experiencing.