Multiple sclerosis

Multiple sclerosisIn multiple sclerosis the patient's immune system attacks myelin which functions as an insulation layer of the brain nerves. Myelin enables a fast conduction of impulses in the brain. This disease, affecting 30 to 80 people per 100,000 inhabitants, is a result of environmental and genetic factors. Multiple sclerosis appears predominantly in the white (Caucasian) race. Women are affected twice as often as men. The course of disease involves exacerbations followed by remissions. During an exacerbation, the following neurological symptoms may appear: decreased visual acuity in one eye, diplopia (double vision), and sensory deficits in various parts of the body, muscle weakness in certain extremities, clumsiness of the hands and disturbances in urination. In 15% of patients with primary-progressive form of disease, the disease progresses smoothly without acute exacerbations.

Why should you have your DNA analysed for predisposition to multiple sclerosis?

Despite numerous studies, the genetics of multiple sclerosis remains largely a mystery. To date, genome analysis has been able to explain a small increase or decrease in the risk of the development of disease in comparison to the rest of the population. The information provided by the genomic analysis is currently essentially of informative rather than practical nature.

How is multiple sclerosis prevented or treated?

Acute exacerbations are treated with intravenous steroids while the disease progression and recurrence of exacerbations are prevented with biological drugs.

More detailed description about multiple sclerosis

A clear and unequivocal cause for the appearance of multiple sclerosis is unknown. The disease is most likely a result of environmental and genetic factors. There are multiple suspected risk factors; various theories cite infections with viruses, retroviruses, spirochetes, Chlamydia as well as the lack of Vitamin D in childhood. Although the disease is not considered hereditary, studies with identical twins have shown that if one of the siblings falls ill with multiple sclerosis, the other twin has a 30% chance of also developing this disease. The HLA (human leukocyte antigen) system plays an important role. It is a genetically determined protein that affects the immune system. Recent research has also shown slight variations in the genes encoding the IL2RA and IL7RA in certain patients with multiple sclerosis. These are genes involved in the production of receptors for interleukin 2 and interleukin 7. Interleukins are signal protein molecules that are involved in immune processes. If their active binding sites (i.e. receptors) are changed, the result is a disturbance in the immune response.

Multiple sclerosis affects 30 to 80 people per 100,000 inhabitants. It is most prevalent in Northern Europe, Canada and the northern parts of the USA. It affects mainly the white race. Women are affected twice as commonly as men. It is a disease of the temperate climates; the incidence declines with the proximity to the equator. The reason for this has not been entirely elucidated yet. The climate, sunlight, diet, infections and genetic factors are all thought to play a role. The environmental factors in childhood supposedly play an important role in the disease development which appears years later.

Disease beginning and its formation

The disease runs a varied course. Most often the signs and symptoms appear in attacks (relapses) which subsequently fade away (remissions). Such a disease form is called the relapsing-remitting type. Between attacks the symptoms may completely disappear, although permanent neurological problems often remain when the disease progresses. In selected patients the symptoms tend to gradually accumulate from the very beginning in the disease course. This is known as the severe progressive type of disease. Many patients start with the relapsing-remitting type and later progress to the progressive type. Such a disease course is termed the secondary progressive type.

The signs and symptoms are varied and differ greatly among the patients. They depend on the location of the inflammatory focus in the brain. The initial attack is characterized by the following disturbances appearing singly or in combination: visual disturbances in one eye, diplopia, sensory disturbances in different body parts, muscle weakness in certain extremities as well as clumsiness of the hands, disturbed movement coordination and balance, fatigue and difficulties with urination and defecation. When an attack subsides, the symptoms may disappear completely in a few weeks although a residual neurological disability usually remains.

According to the immunologic explanation, the inflammatory process in the brain is triggered by the activated T lymphocytes. However, these cells enter the brain only after the blood-brain barrier has been damaged, for instance by a viral infection. Upon entering the brain, T lymphocytes fail to recognize the patient's own myelin and thus they attack it. An immune process is triggered, attracting other inflammatory cells as well and activating additional inflammatory mediators such as cytokines and metalloproteinases which additionally damage the blood-brain barrier. A vicious cycle is created, but the inflammation nevertheless subsides with time. Despite it, however, some scars remain in the tissue. A phase of repair and remyelinization follows, but the initial state is never attained. Some axons also suffer permanent damage. The signs and symptoms are thus the result of the accumulation and location of such lesions in the brain and the spinal cord.

Disease diagnosis

Diagnosis is made on the basis of diagnostic criteria. Nowadays, McDonald criteria are used which take into consideration not only the clinical picture (the number of attacks and neurological disturbances), but also the number of inflammatory foci revealed by the magnetic resonance imaging (MRI) of the brain and the spinal cord. In essence, it is still about determining the course of disease "in time and space".

Prevention and therapy

Multiple sclerosis still cannot be cured or prevented. It is only possible to influence its progression and reduce the number of flare-ups. A general rule that applies in case of this disease is the need to avoid excessive physical and psychological stressors, and especially situations that can stir up the immune system, such as colds because an infection may trigger a flare-up.

Research has shown that the flu vaccination does not hurt these patients, nor does it cause new flare-ups. Nutrition must be varied; first and foremost, it should include enough vitamins that may also be supplemented. High temperatures such as those found in sauna or hot baths may transiently worsen the symptoms; thus, exposure to heat is not recommended. Adequate physical exercise and keeping fit is also beneficial as fatigue is a prominent symptom of this disease.

The use of medication

Sudden exacerbations or flare-ups are treated with corticosteroids that act fast to contain the flare-ups. In addition, the aim is to prevent new flare-ups and disease progression. To this effect, biological medicines that suppress the immune system have been used in the past years, mainly the interferon-beta and glatiramer acetate. A novel and very potent drug is natalizumab which prevents inflammatory cells to cross the blood-brain barrier and cause brain lesions typical of multiple sclerosis. Natalizumab is used for rapidly progressing cases where interferons are not sufficiently effective. There are numerous other drugs on their way, currently in the last phase of clinical trials.