Around 85% of people with MS will start off with a relapsing-remitting disease course. After some years, a portion of people with RRMS find that their disease is progressing gradually, even though they are no longer experiencing relapses (or at least have very few relapses). This is then called secondary progressive or SPMS).
SPMS seems to mark a turning point. The disease becomes less ‘inflammatory’, with fewer acute relapses. Instead, gradual and irreversible disease progression can occur.
There are no reliable laboratory markers or specific tests to differentiate RRMS from SPMS, so the conversion to SPMS is determined by neurologists based on clinical findings. It has been reported that after five years of having MS, nearly 10% of those with RRMS had reached SP stage. This increased to almost 25% at ten years and 75% at 30 years.
Prognosis
On average, the RR phase lasts around two decades before SPMS begins. However, as indicated above, some people reach the progressive phase much more quickly than others, and some never reach it at all. Based on research, it appears that people who are younger at the onset of MS take longer to reach SP stage. Yet these people still tend to reach SPMS at a younger age than those who are older at the onset of MS. Men typically reach SPMS around five years earlier than women (from the onset of MS); from the perspective of age, men reach SPMS at around 47 years of age, with women averaging 50 years.
Once secondary progression has been reached, it becomes more difficult to make general statements about the prognosis. We do know that people who take longer to reach the SP phase also progress more slowly once in that phase.
Treatment
Disease-modifying drugs
We do not know if any drug can actually delay the onset of secondary progressive MS. This is, in part, because most clinical trials only last two to three years, while secondary progression can take decades to develop. Once secondary progression is reached, it seems to mark a change in the effectiveness of drug therapy.
Most of the currently licensed drugs for MS, the so-called disease modifying drugs, such as betainterferon or glatiramer acetate, are not very effective in SPMS. If a person is still experiencing relapses these drugs can help reduce the risk of a future relapse, but they do not appear to have a long-term impact on disease progression, although this is under debate. The possible beneficial effect on reducing the number and intensity of relapses has to be balanced with the fact that during the SP phase, people tend to experience fewer and fewer relapses anyway. Thusthe risk of treatment (that is, risk of side effects) might be greater than any expected benefits.
Other drugs, such as mitoxantrone (a drug also used to treat some types of cancer), might be suitable for some people with aggressive SPMS, but again, serious risks, such as cardiac side effects and leukemia, need to be considered.
Newer drugs, such as natalizumab, are not approved for use in SPMS and we do not know whether they are effective or not in SPMS. There are a number of other drugs currently in clinical trials designed to prevent disease progression in SPMS. These include an oral cannabis extract (dronabinol, in the UK); cyclophosphamide (France) and lamotrigine (UK). For more details and updates, see http://www.nationalmssociety.org/research/clinical-trials/index.aspx.
Symptomatic treatments
There are a number of effective drugs to manage the symptoms of MS, such as spasticity, bladder issues or pain. These drugs can be just as effective in SPMS as in RRMS. They do not affect disease progression, but they can alleviate troublesome symptoms and enhance quality of life.
Short courses of oral or intravenous corticosteroids are also available to accelerate recovery from a relapse if one does occur, but they do not affect the long-term outcome or overall disease progression.
Many non-pharmacological approaches can be helpful in SPMS, including the common sense approach of maintaining a healthy lifestyle, a balanced diet and regular exercise.
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