Really, everyone with MS has a different course to their condition. They're often divided into four main "types", though, based on a survey of neurologists in 1996. To a large degree, the classification depends on whether the person has relapses. An MS relapse can be thought of as an episode of neurological symptoms, occurring at least 30 days after any previous episode began, lasting at least 24 hours, and not caused by anything else (eg an infection).
Relapses are caused by inflammation in the central nervous system (brain and spinal cord), caused by the body's immune system mistakenly reacting to the myelin surrounding nerve fibres. When messages are blocked in an area with a specific function (eg movement, speech, vision), symptoms may occur.
In the graphs that follow (from the wonderful http://www.mult-sclerosis.org), a rising line shows an increase in disability over time.
In relapsing-remitting MS (or RRMS), people have attacks (also called relapses, flares or exacerbations). During these new symptoms can appear, or old ones reappear or worsen. In between the attacks are periods of remission, during which the person recovers wholly or partially. Relapses can last days, weeks or months. The vast majority of people with MS have RRMS to begin with.
In PPMS there is a gradual progression from the outset with no remissions. The word "primary" is used to show that the progression is right from the beginning of the condition, whereas in SPMS it comes after RRMS. PPMS tends to start in the late 30s or 40s (as opposed to the 20s or 30s for RRMS) and is as common in men as in women, whereas other forms of MS are about twice as common in women as in men. Initial disease activity is in the spinal cord, not the brain. It may later move into the brain, but is less likely to damage brain areas: for instance, people with PPMS are less likely than other people with MS to develop cognitive problems.
Other terms are still in use to describe forms of MS. Some you may hear include:
- Benign MS: Used to describe people who have had MS for 15 or more years without picking up any serious and enduring disability. People with benign MS are often reclassified as having SPMS.
- Malignant MS: also known as Marburg's Variant and Acute MS. A label given to forms of MS where the condition proceeds to severe disability in a very short period of time. Fortunately very rare.
- Chronic Progressive MS: PPMS and SPMS used to be lumped together as one as CPMS.
- ...and there are others.
When research is being carried out, having participants with only one form of MS helps keep the results "pure". And the results of that research can be targeted: if (for instance, as above) it shows that people with PPMS are less likely to have cognitive problems than people with other forms of MS, perhaps neuropsychiatry services could be targeted accordingly.
What with MS being such a variable condition though, and us all being individuals, it's inevitable that a lot of us won't fit perfectly into the categories. I don't, for one. My disease course is pretty much relapsing progressive - except that you're not meant to have an RRMS phase before that, and I did. Do we all want to be treated as "identikit" patients, considered to be the same regardless of our differences?
The same research in which it can seem so useful to separate people into disease types can end up by excluding some patients from potentially useful treatments. The new oral medication Gilenya is already approved in the USA, and it looks likely that it will soon be licensed in Europe. It reduces the number and severity of relapses. I have relapses as part of my relapsing progressive MS, but because Gilenya has only been tested in RRMS (by far the biggest patient group with relapses), it will only be approved for people with RRMS.
Being moved from one "box" to another can be a very traumatic experience. Many neurologists don't seem to realise how much. Being diagnosed with MS is a huge trauma in the first place, and it can take many years to adjust to your new "self". Being told, sometimes quite abruptly, that you now have a progressive form of the condition (read: it's all downhill from here kiddo) is something that needs another major adjustment. This is something I believe healthcare professionals really need to consider.
So, types of MS. Good or bad? Overall, the jury's out, I'd say. For you as an individual? Just remember, you're you, and your MS is as individual as you are! (dammit ;-)