MS is very unpredictable and it often defies its own classifications. Many patients note that although they have relapsing/remitting MS, they seem to have lingering symptoms after definite attacks. The same holds true for those who were diagnosed with primary progressive multiple sclerosis and who find themselves experiencing “attacks” as well as steady disease progression. In years past, there were four recognized disease courses, but as of late, neurologists and MS scientists are acknowledging several other multiple sclerosis disease patterns.
Silent MS
Not much is known about this type of multiple sclerosis. Apparently, a small amount of people live their lives with no physical symptoms of multiple sclerosis, and it is only upon death (during autopsies) that doctors learn about this group of patients through their discovered brain and spinal cord lesions.
Benign MS
This form of multiple sclerosis accounts for about 10-20% of the MS population. It is marked by few attacks with long periods of remission, with little accumulated disability. Often doctors use this term for patients who have suffered isolated, single attacks, but the true form of this course can only be judged after years of the disease with few serious attacks. Sometimes this is also referred to as “mild” MS.
Relapsing-Remitting MS
RRMS is the most common form of multiple sclerosis, both at disease onset (85% of all cases) and as a part of the overall, collective types of MS (up to 45% of all patients.) Onset is generally sudden, with an actual attack marking the beginning of the disease, followed by a period of remission with full or partial recovery from the attack. RRMS varies greatly among patients. Some experience small, non-debilitating attacks that last for a week or so, while others have full-blown attacks that can perpetuate for a month or more. Whatever the magnitude of the attacks, it has been observed that they usually become harder to rebound from as time goes on, and about 50% of RRMS patients enter a secondary progressive phase after about 10 years of the disease, while as many as 80% or more of RRMS patients enter it after 20 years of the disease. Statistics for patients who take disease-modifying drugs are not yet conclusive, since these medications have only been around since the early 1990’s.
Secondary-Progressive MS
This form of multiple sclerosis is exactly what its name implies: the second phase in a course of MS. RRMS patients have a 50% chance of developing this variety of MS after 10 years if they are not treated with disease-modifying medication. At the 20 year mark, as many as 80% or more of RRMS patients will enter this phase if not treated with medication. At this time, specific data is not available for the percentage of patients who enter this phase who do take disease-modifying meds. SPMS is defined as the stage where patients stop having clear attacks and clear remissions and begin to have gradual, steady decline and mounting disability. Approximately 40% of the MS population lives with this type of disease.
Primary-Progressive MS
This form of MS is usually more aggressive from the onset. It tends to occur more in men and those who are 40 years or older at the time of disease onset. There are no clear attacks and remissions, and decline and disability are gradual but continuous. This accounts for about 5-10% of the entire MS population.
Progressive-Relapsing MS
This is a little-acknowledged disease course because it overlaps with RRMS and PPMS. What is known is that there is a clear progression of disability from the beginning of disease onset, but there may be overlaps of attacks (relapses) and remissions that may or may not display full recovery. There is no clear percentage of patients who live with this form of the disease.
Marburg’s Disease or Malignant MS
This is a very rare form of MS that has a severely progressive course and can be fatal within several months to several years. It generally strikes at a very young age (under 20 years) and most doctors see very few cases of this during the courses of their medical careers.
References:
- Barnes, David. Multiple Sclerosis Questions and Answers. Merit Publishing International: Coral Springs, Florida, 2000.
- Kalb, Rosalind C., PhD. Multiple Sclerosis: The Questions You Have, The Answers You Need, 4th Ed. Demos Medical Publishing, LLC: New York, NY, 2008.
- Rosner, Louis J., MD, and Shelley Ross. Multiple Sclerosis: New Hope and Practical Advice for People with MS and Their Families. Simon & Schuster: New York, NY, 2008.
