Multiple Sclerosis (MS) is one of the most commonly encountered neurological diseases, yet its cause is unknown and its course unpredictable. MS is a disorder of the brain and spinal cord which results from a scattered loss of myelin, a fatty substance that surrounds the nerve cells. Myelin is considered important for separating nerve pathways from each other, so that impulses can travel from one location in the nervous system to another. "Multiple" comes from the multiple sites where the disease is scattered in the brain and spinal cord. "Sclerosis" refers to "sclera" or scar tissue which can obstruct or distort the flow of messages between nerves and to muscles.
About 350,000 people nationwide have MS. MS affects people of all ages, but is most likely to begin between the ages of 20 and 40. Women are twice as likely as men to develop MS. MS differs markedly from one patient to another.
MS is diagnosed on the basis of the patient's history of symptoms, a detailed neurological examination, magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) analysis.
According to the clinical pattern of relapses and residual disability experienced, patients are classified as having one of four patterns of MS, representing a continuum of disease:
Benign
Relapsing-remitting
Secondary progressive
Primary progressive
Benign MS
Patients stay relatively unimpaired for many years after an initial attack. Approximately 20% of patients have this form of disease.
Relapsing-Remitting MS
This is the usual pattern of disease in the first 20 years experienced by around 85 per cent of patients. They experience periodic attacks associated with some degree of impairment which subsequently resolves to a large degree if not completely. Around 25% - 35% of patients have this pattern at any one time. More than 80% of patients progress from relapsing-remitting MS to the secondary progressive form.
Secondary Progressive MS
This form of the disease is marked by fewer remissions occurring after attacks and accumulating disability between relapses. An estimated 40% of MS patients are in this category.
Primary Progressive MS
This is characterised by a gradual, insidious and progressive deterioration with disability developing from the onset of disease without remissions. About 10% or fewer MS patients have this condition.
The extent of a patient's neurological disability and deterioration is assessed, usually for clinical trial purposes, on the Kurtzke expanded disability scale (EDSS).4 This ranges from 0 (normal) to 10 (death) with the steps in between representing an increasing loss of neurological function. A score of 3 reflects moderate disability, 7 indicates a patient is wheelchair bound, and a score of 8, means bed bound.
Treatments for MS fall into three categories.
Acute
Symptomatic
Disease-modifying
Acute
Drugs used to treat acute exacerbations or relapses are usually the corticosteroids such as methylprednisolone. They reduce inflammation and shorten the time to recovery after a relapse. They do not affect the course of MS and in any case could not be taken long term because of their well-known side effects.
Symptomatic
Drugs used to control symptoms experienced by MS patients include those to ease pain, spasticity, depression, fatigue and urinary problems. Other non-drug treatments such as physiotherapy are helpful in teaching patients to circumvent the problems caused by MS.
Disease-Modifying
The only drugs demonstrated to alter the natural course of MS include interferon beta-1b (Betaferon, Betaseron), interferon beta-1a (Avonex, Rebif) and glatiramer acetate (Copaxone). Of these, only Betaferon/Betaseron is licensed for the treatment of both relapsing-remitting and secondary progressive MS. Rebif, Avonex and, in some countries, Copaxone, are only indicated for use in patients with relapsing-remitting MS. All the interferon therapies and Copaxone have demonstrated an ability to reduce the number of expected relapses in relapsing-remitting MS. Only Betaferon/Betaseron has been able to demonstrate an ability to slow the progression of disease in secondary progressive MS and delay the onset of severe disability.
Interferons are cytokines with the capacity to modulate the activity of the human immune system. For example, Betaferon prevents activated T-lymphocytes penetrating the blood brain barrier and intercepts to inhibit their destructive cascade of activity.
It is often very difficult to predict the course of MS. The great variability of this disorder must be considered in each individual case. Some studies have shown that the degree of disability present at five years after the onset of symptoms is a good predictor of disability at 10 or 15 years after onset, and many neurologists use this "five year" rule in predicting a person's course. Other studies suggest that sensory problems (e.g., loss of feeling on the skin's surface, "pins and needles," or increased sensitivity to pain) are associated with a good prognosis, that is, a relatively benign course. Early onset of cerebellar findings, (e.g., tremor, coordination problems and slurred speech) tend to be linked to a more progressive disease course.
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