From: National Multiple Sclerosis Society
The Disease
What is multiple sclerosis?
Multiple sclerosis (MS) is a chronic, progressive disease of the central nervous system (the brain, optic nerves, and spinal cord), which is characterized by the destruction of the fatty sheath -- or myelin -- which insulates the nerve fibers within the central nervous system (CNS). This destructive process is called demyelination. Myelin helps transmit messages -- or nerve impulses -- to and from the brain and among other parts of the body. When nerve fibers lose part of their myelin, the impulses they send are no longer transmitted properly. The areas where the myelin has been damaged or destroyed are called "plaques." Plaques result in scars in different areas of the CNS and are linked to a variety of frustrating and debilitating neurological symptoms for the sufferer.
Who is affected ?
MS affects more than 1 million people worldwide, including an estimated 450,000 people in Europe alone. It is the most common neurological disease among young adults. MS affects twice as many women as men and typically develops between the ages of 20 and 40 years. The most common age of onset is 31 to 33 years. MS is rarely diagnosed in children or elderly persons. While the disease occurs in all races, studies have shown that the disease is most prevalent among Caucasians. The risk of developing MS among the general population in approximately 1 in 1000.
What causes the disease?
The cause of MS is unknown, though a number of theories exist. MS is considered an "auto-immune" disease -- one that occurs when the body is no longer able to differentiate its own cells from foreign agents and subsequently begins to destroy its own tissues. In patients with MS, the myelin sheaths that include the nerve fibers become the target of an attack orchestrated by the patient's own white blood cells (T and B-lymphocytes and macrophages). Some researchers believe that this auto-immune reaction may be the result of any one of a number of common viral infections, such as the measles.
Is MS hereditary?
MS is not contagious or hereditary, although there is a higher incidence of MS among family members -- particularly identical twins -- suggesting to some researchers that certain individuals may be genetically susceptible to the disease.
What are the symptoms of MS?
The nature of the symptoms of MS are determined by the location of the lesions -- or plaques -- in the CNS. For example, a lesion of the optic nerve may cause impaired vision, and a lesion on the spinal cord may cause weakness or numbness of the extremities.
| Symptoms | Location of CNS Lesions |
|---|---|
| optic neuritis, blurred vision, nystagmus | optic nerve |
| dizziness, co-ordination and balance problems, vertigo | brain stem |
| weakness, tingling, numbness of the extremities, ataxia, spasticity | spinal cord and brain |
The most frequent symptoms of MS are typically accompanied by progressive weakness and fatigue and include sensory disturbances (tingling, numbness, itching, pain), impaired vision (loss of sight in one eye, double or blurred vision), muscle function problems (spasticity, tremors, incontinence, constipation, sexual dysfunction, facial pain), and equilibrium disorders (imbalance, clumsiness, poor coordination, paralysis, vertigo).
The hallmark of MS is the relapse or exacerbation -- the unprovoked and unanticipated occurrence of a new symptom or recurrence of an old symptom, lasting for a period of greater than 24 hours. The time and course of a typical relapse or exacerbation is relatively consistent: symptoms usually develop over a matter of days, remain constant for 3 to 4 weeks, and then slowly resolve over a period of about one month.
How does the disease progress over time?
The course of MS is unpredictable, as it is impossible to determine the nature, severity, or timing of the disease progression from patient to patient. However, five general categories of the disease have been identified based upon the pattern and frequency of the appearance of symptoms (see below).
| Type | Frequency of cases EDSS scores | Disease course |
|---|---|---|
| Benign | 10% of MS patients | characterized by complete recovery from isolated exacerbations. Patients do not become disabled. |
| Relapsing- remitting(RRMS) | 35% of MS patients | characterized by the unpredictable occurrence of new symptoms or the worsening of old symptoms. |
| Transitional (TMS) | 5% of MS patients | characterized by a history of RRMS, established ambulatory disability, and a high risk of progression to secondary progressive MS. |
| Secondary progressive(SPMS) | 40% of MS patients | characterized by isolated relapses, like RRMS, but recovery is incomplete and disability progresses between exacerbations. These patients will eventually become moderately or severely disabled. |
| Primary progressive(PPMS) | 10% of MS patients | characterized by the occurrence of relapses that steadily worsen the symptoms and lead to death. |
The Kurtzke Expanded Disability Status Scale (EDSS) (see table below) is a scoring system commonly used to rate the degree of disability of people with MS and follow the progression of their disease. The scale relies on signs and symptoms observed during standard neurological examination.
Kurtzke Expanded Disability Status Scale (Simplified)
| Grade | Status |
|---|---|
| 0 | Normal neurological examination |
| 1.0 | No disability, minimal signs in one FS* |
| 2.0 | Minimal disability in one FS* |
| 3.0 | Moderate disability in one FS*, or mild disability in three or four FS. Patient is fully ambulatory |
| 4.0 | Patient still fully ambulatory, self-sufficient and up 12 hours a day despite relatively severe disability in one FS. Able to walk some 500 meters without aid or rest. |
| 5.0 | Ambulatory without aid or rest for about 200 meters. Disability severe enough to impair full daily activities. |
| 6.0 | Intermittent and unilateral assistance needed to walk (cane, crutch or brace) required to walk about 100 meters. |
| 7.0 | Unable to walk more than 5 meters even with aid; essentially restricted to wheelchair. |
| 8.0 | Essentially restricted to bed or chair. Unable to use wheelchair alone. |
| 9.0 | Helpless bed patient; can still communicate and eat. |
| 10.0 | Death due to MS. |
