MULTIPLE SCLEROSIS

 

Multiple Sclerosis (MS) – is a chronic, degenerative, progressive disease of the central nervous system (CNS) characterized by small patches of demyelinization in the brain and spinal cord. Demyelinization (destruction of myelin) results in impaired transmission of nerve impulses (Brunner & Sudarth’s, 2010) . This damage disrupts the ability of parts of the nervous system to communicate resulting in a range of signs and symptoms including physical, mental, and sometimes psychiatric problems. Specific symptoms include double vision, blindness in one eye, muscle weakness, trouble with sensation, or trouble with coordination.


 
 

While the cause is not known, the underlying mechanism is thought to be either destruction of the immune system or failure of the myelin-producing cells. A defective immune response probably plays a major role. In MS, sensitized T cells inhabit the CNS and facilitate the infiltration of other agents the damage the immune system. The immune system attack leads to inflammation which is the other sign of the disease.

Fitting with an immunological explanation, the inflammatory process is caused by T cells, a kind of lymphocyte that plays an important role in body’s defenses. T cells gain entry in the brain via disruptions in the blood brain barrier. The T cells recognize myelin as foreign and attack it, explaining why the cells are also called “autoreactive lymphocytes”. Myelin protects the nerve fibers in the CNS which helps messages travel quickly and smoothly between the brain and the rest of the body.



Inflammation can potentially reduce transmission of information between neurons in at least three ways:
    1. The soluble factors (cytokines and antibodies) released might stop neurotransmission by intact neurons
    2. These factors ( cytokines and antibodies) could lead to or enhance the loss of myelin
    3. These factors may also cause the axon to break down completely.


A blood-brain barrier (BBB) is a part of capillary system that prevents the entry of T cells into the central nervous system. It may become permeable of these types of cells secondary to infection by a virus or bacteria. After it repairs itself, typically once the infection has cleared T cells may remain trapped inside the brain.


Geographical Prevalence:
Multiple sclerosis is the most common autoimmune disorder affecting the central nervous system. In 2013, about 2.3 million people were affected globally with rates varying widely different regions and among different populations. That year about 20, 000 people died from MS, up from 12,000 in 1990.
Geographic prevalence is highest in Europe, New Zealand, Southern Australia, the Northern United States and Southern Canada.


Middle Eastern and Northern Africa countries are located in a low-to-moderate risk zone for MS based on the 2013 MS Atlas, however, recent studies suggest a moderate-to high prevalence in areas within this region, with an increase prevalence among women.
In a single-hospital based centers study, MS prevalence in Saudi Arabia is low with 25 per 100,000. (Yaqub BA, Daif AK 1988)
Multiple sclerosis may occur at any age but typically manifests in young adults between the ages of 20-40 years, it affects women more frequently than men.


Disease Course:
Multiple sclerosis has various courses. Several phenotypes (commonly named types), have been described. Phenotypes use the past course of the disease to attempt to predict the future course. They are important not only for prognosis but also for treatment decisions.
     1. Relapsing – remitting (RRMS) – this subtype is characterized by unpredictable relapses (deterioration after a period of improvement) followed by periods of months to years of relative quiet remission (period of improvement) with no signs of disease activity.
     2. Secondary progressive (SPMS) – occurs in around 65% of those with relapsing-remitting MS, who eventually have progressive neurologic decline between acute attacks without definite periods of remission.
     3. Primary progressive (PPMS) – occurs in approximately 10-20% of individuals, with no remission after the initial symptoms. It is characterized by progression of disability from onset, with no, or occasional and minor, remissions and improvements.
     4. Progressive relapsing (PRMS) - describes those individuals who, from onset, have steady neurologic decline but also have clear superimposed attacks.


Signs and Symptoms - are varied and multiple and reflect the location of the lesions.
 Primary symptoms include:
• Fatigue
• Depression
• Weakness
• Numbness
• Difficulty in coordination
• Loss of balance
• Pain


 Visual disturbances:
• Blurring of vision
• Diplopia (double vision)
• Patchy blindness (scotoma)
• Total blindness


 Spastic:
• Weakness of the extremities
• Loss of abdominal reflexes
• Ataxia (difficulties in coordination and balance)
• Tremors


 Cognitive and psychosocial problems:
• Depression
• Emotional lability
• Euphoria


 Bladder, bowel, and sexual problems possible Secondary manifestations related to complications:
• Urinary tract infections, constipation
• Pressure ulcers, contracture deformities, dependent pedal edema
• Pneumonia
• Reactive depressions and osteoporosis
• Emotional, social, marital, economic, and vocational problems


Medical management
Because there is no cure exists for MS, the goals of treatment are to delay the progression of the disease, manage chronic symptoms, and treat acute exacerbations (increase in the severity of signs and symptoms or the disease). An individualized treatment program is indicated to relieve symptoms and provide support. Management strategies target the various motor and sensory symptoms and effects of immobility that can occur. Radiation therapy may be used to induce immunosuppression.


Prognosis
The expected future course of the disease depends on the subtype of the disease; the individual’s sex, age, and initial symptoms; and the degree of disability the person has. Female sex, relapsing-remitting subtype, optic neuritis or sensory symptoms at onset, are associated with a better course.
The average life expectancy is 30 years from the start of the disease, which is 5 to 10 years less than the unaffected population. Almost 40% of people with MS reach the seventh decade (age 60 – 69). Nevertheless, two-thirds of the deaths are directly related to consequences of the disease. Suicide is more common, while infections and other complications are especially dangerous for the more disabled.