Multiple sclerosis is a chronic, often disabling disease that attacks the central nervous system. Symptoms may be mild, such as numbness in the limbs, or severe, such as paralysis or loss of vision.
The progress, severity, and specific symptoms of MS are unpredictable and vary from one person to another. There are 4 distinct disease courses of multiple sclerosis.
Relapsing-Remitting Multiple Sclerosis
People with Relapsing-Remitting Multiple Sclerosis (RRMS) 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 RRMS.
The disease course of Primary-Progressive Multiple Sclerosis (PPMS) is characterized by slowly worsening neurologic function from the beginning with no distinct relapses or remissions. A person’s rate of progression may vary over time, with occasional plateaus or temporary improvements, but the progression is continuous. The rate of progression may vary over time, with occasional plateaus and temporary minor improvements. Doctors diagnose approximately 10% of MS patients with PPMS.
Secondary-Progressive Multiple Sclerosis
Following an initial period of RRMS, 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 RRMS developed this form of the disease within 10 years. Long-term data are not yet available to determine if treatment significantly delays this transition.
Progressive-Relapsing Multiple Sclerosis (PRMS) is a relatively rare course of MS, occurring in approximately 5% of sufferers. 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. Because PRMS is progressive from onset, the doctor may initially diagnose it as PPMS, subsequently changing the diagnosis to PRMS when a relapse occurs. Although this disease course is progressive from the outset, each person’s symptoms and rate of progression will be different.