Ana sayfa | MS’in Derinliği  | MS Slide Resource

Multiple sclerosis (MS) is an inflammatory, demyelinating disease that is specific to the central nervous system (CNS). The disease, which is likely to be autoimmune in nature, is the most common cause of chronic neurological disability among young adults. MS is characterized by discrete demyelinating lesions (plaques) scattered throughout the CNS. These plaques can occur at different sites in the CNS at different times, with some sites of predilection - such as the optic nerve.¹

The random nature of MS lesions results in a wide variety of clinical features, such as loss of (or abnormal) sensations, muscle weakness, visual loss, loss of co-ordination, cognitive impairment, psychiatric abnormality, fatigue, pain, and loss of bladder control.² However, the disease is complex and these features vary from time to time and from patient to patient.³

The mean age of disease onset is 30 years. The initial diagnosis of MS is only rarely made in patients whose ages are outside the range of 10 to 59 years.⁴ Onset in females tends to be a year or two earlier than in males.⁴ In addition, females are more susceptible to MS than are males by a factor that approaches 2:1.⁴ Race is another factor that affects susceptibility to MS. In general, whites are more susceptible to MS than are blacks or orientals.⁵

The picture is complicated further by an apparent geographical gradient of MS risk, which, as a general rule, increases with increased distance from the equator.⁵ Migration between regions of differing latitude at an early age is associated with a change in risk.⁵ (See below for a more detailed examination of these and other related topics.)

Patient categories in MS

The natural course of MS is extremely variable.⁵ Symptoms may appear, disappear and reappear; they can gradually worsen or remained unchanged for extended periods. Despite this variability, it is possible to recognize broad categories of disease and to classify MS patients according to the course of their disease.

A variety of terms are used to describe the patterns of disease. Unless they are specifically defined for research purposes, these terms do not have precise meanings. However, three concepts are useful: relapsing/remitting, chronic progressive, and benign MS.

Relapsing/remitting MS

This form of MS begins with the acute or sub-acute onset of neurological symptoms, from which most patients recover either completely or partially.^6,7 Further attacks (relapses or exacerbations) occur at irregular intervals.

A relapse is the appearance of a new symptom, the reappearance of a previous symptom, or worsening of an existing symptom, at any time after the initial attack. A true relapse persist for more than 24 to 48 hours. Recovery from such relapses may be complete, but if it is not the patient's disability will increase over time. Therefore, the category of relapsing/ remitting MS includes patients with varying levels of disability.

Reported prevalence rates for this pattern of disease differ from study to study, depending on the precise definition of relapsing/remitting MS used by the investigators. However, Weinshenker et al. provide a useful guide: they found that, at least in the early phase of the disease, 66% to 85% of their patients had relapsing/remitting disease (the variation in percentage depends on the population studied).⁸

Chronic progressive MS

There are two forms of chronic progressive MS: primary and secondary. Some patients never improve following disease onset. Instead, disability becomes steadily worse, with no relapses or remissions. This is primary progressive MS. Estimates of its prevalence vary from 9% to 37%, although most reviewers quote a prevalence of around 10%.^1,6

With time, relapsing/remitting MS usually converts to a disease pattern of gradual accumulation of irreversible disability. This is termed secondary progressive MS.⁶ The proportion of patients developing progressive disease increases with length of follow-up. Weinshenker et al. found that 41% of relapsing/ remitting patients had entered the secondary progressive phase within 6 to 10 years of disease onset.⁸

When examined between 11 and 15 years after onset, 58% of the original population had converted to a progressive course.⁸

Secondary progression proceeds in different ways in different patients. Most commonly, there is a slow, steady deterioration, but sometimes an initial rapid progression is followed by a slower accumulation of disability. Alternatively, disability may remain static for long periods, and several other variations are possible. Whatever the pattern of slow progression, once established, disability infrequently remits.

Magnetic resonance imaging (MRI) suggests that primary and secondary progressive MS are biologically distinct.⁶ In practice, however, the two may not always be differentiated. Onset of primary progressive MS tends to occur later (around 37 years of age) than relapsing/remitting disease.⁷

Benign MS

Benign MS is characterized by either little disability many years after diagnosis, or very slow accumulation of disability over time.⁷ In the mildest cases, MS is discovered only at post-mortem examination late in life. The definition of benign MS is arbitrary, and there is no compelling reason to think of it as a distinct entity.

Regardless of how benign MS is defined, all studies show that some patients have only slight disability after a long disease duration. Conversely, MS experts recognize that, unpredictably, long-standing benign disease can become more aggressive, leading to severe disability.⁸ Overall, at 10 years post-diagnosis, one-third of patients have benign disease (little or no disability); this proportion decreases to one-fifth by 20 years.⁶

MS progression: The physical results

The variability of MS makes it very difficult to predict how individual patients will be affected by their disease. The following account describes the progression of a 'typical' case of moderately severe MS. However, it is important to remember that for many patients their experience of MS will differ from the following example.⁹

Case history

Within a few weeks of an initial attack of sensory disturbance, the patient, perhaps a woman of about 24 years old, recovers completely. At this stage it is likely that no diagnosis has been made.

The disease becomes latent, and there may be an interval of several months to several years before further symptoms develop. These symptoms usually, but not always, differ from those of the initial attack.⁹ Once again, recovery is complete.

A second relapse occurs within the next two years. This time the symptoms may include weakness in both legs.⁹ Permanent, slightly disabling symptoms persist after this attack (e.g. weakness in one leg when tired, and an inability to run).

For a further three or four years, relapses occur at a rate of one every 6 to 24 months. Each time recovery is less complete and the symptoms that remain are more severe. Eventually, there is persistent difficulty in walking, perhaps tremor, and probably a loss of normal bladder control.⁹

Following the active stage of relapse and remission, which lasts for several years, the pattern of disease is likely to change. Acute attacks and spontaneous recovery no longer occur. The severity of symptoms remains static, although there may be some fluctuation from day to day, and during the course of a day. Many patients remain at this stage for many years.⁹

In more severe MS, this period of relative stabilitesini eventually gives way to the progressive stage, when disability increases over time until the patient needs constant nursing care. This may continue for many years until complications, such as renal infection or pneumonia, cause death.⁹

The outcome of MS

Most patients with MS die from the complications of immobility (such as infection), or from unrelated disease. Although death may, very rarely, occur within 1 to 2 years, the average duration of life is at least 25 years. One study found that 50% of men with MS survive for more than 35 years after disease onset.⁹

Bu sayfadaki bilginin en son güncellendiği/doğrulandığı tarih:

11/09/2001

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