Multiple Sclerosis

Multiple Sclerosis

Introduction:

Multiple Sclerosis (MS) is a disease of the central nervous system which leads to recurring attacks of neurological symptoms. The deterioration in function is related to something termed "demyelination".

Nerve cells connect to other nerve cells at a distance by way of a long wire-like extension of the cell called an axon. The axon carries an electrical signal along its length to transmit messages from one cell to the next. These can be quite long, carrying nervous system impulses up to feet at a time through the spinal cord and brain. Most of these long axons are myelinated, wrapped in an insulating substance called myelin. The myelin helps the electrical impulses conduct quickly and efficiently down the length of the axon.

In MS, the myelin sheath around some axons in the central nervous system becomes damaged. This damage makes conduction along these axons faulty, slowing or stopping completely, leading to symptoms. These areas of demyelination, called MS plaques, are patchy and can occur almost anywhere in the brain or spinal cord at various times. The specific symptoms that occur depend on the specific location of the demyelination within the nervous system. The pattern and time course of these occurrences varies depending on the type of multiple sclerosis. Most commonly, the demyelination occurs in attacks which then resolve, the symptoms improving partially or completely. Further attacks then occur at a later date.

Cause of Multiple Sclerosis:

The exact cause of multiple sclerosis is not well understood. What is fairly well accepted is that the damage to the myelin sheath, the "insulation" of nerve fibers, which characterizes MS and causes its primary symptoms, is caused by an autoimmune (against your own body tissues) attack on the myelin producing cells, called oligodendrocytes. It is unclear what initiates this inflammatory reaction, but the immune system, which should usually be able to tell "self" from "non-self", gets confused and attacks the myelin sheath in the central nervous system. Normally the immune system is important for fighting disease, fighting off invaders (bacteria, viruses, fungi, etc.), getting rid of foreign substances and abnormal cells. There are several types of autoimmune diseases and for most the underlying cause is not well understood. Likely, the underlying etiology that leads to the disease is multifactorial, resulting from some combination of environmental and genetic factors.

Environmental Factors:

An interesting finding in the prevalence of multiple sclerosis is that it occurs more frequently in parts of the world which are further from the equator. It is quite common in northern Europe, in Scotland and the Scandinavian countries. However, if people born in these areas move to areas with lower risk (closer to the equator) their risk of developing the disease drops to about that of others. This implies that some environmental factor in higher latitudes may play a part in the underlying cause of multiple sclerosis. The details of this environmental influence are not well understood.

Genetic Factors:

People with close relatives with MS are at higher risk for MS. Therefore it is assumed that there are some genetic factors which help predispose to the disease, although this does not seem to be the only cause. It is likely that any such genetic predisposition is related to multiple genes as no single gene abnormality has been associated with the disease.

Other Factors:

Researchers have long hypothesized that some virus could be linked to MS, perhaps setting off the autoimmune attack. However, this has not been proven and no virus has been consistently to be associated with MS. There is also some evidence that hormone activity, particularly the sex hormones, may be associated with the disease; but again the details of this association are not clear.

Multiple Sclerosis Symptoms:

Generalizing multiple sclerosis symptoms can be difficult because it can affect each patient differently. Because multiple sclerosis can cause demyelination of nerve fibers in any part of the central nervous system (brain and spinal cord) the variety of types of symptoms which can occur is great. In theory, just about any normal function of the central nervous system can become dysfunctional if affected by multiple sclerosis and lead to related symptoms of nervous system function.

Commonly, multiple sclerosis symptoms come on in attacks which affect one or more parts of the nervous system. These attacks last a variable amount of time and in the most common types of MS will then slowly recover. Each new attack of MS can vary in the parts of the nervous system that is affected and, therefore, the associated symptoms.

While the exhaustive list of possible symptoms of MS is long, there are some common types of symptoms which can affect many patients at one time or another. Again, the specifics of these symptoms, their location in the body, their severity and their duration varies considerably from one patient to the next.

Types of Possible MS Symptoms:

• Sensory: Including numbness, tingling, and pain.
• Motor: Including weakness in one or more limbs, spasticity and muscle spasm, tremors, facial paralysis, etc.
• Coordination and Balance: Including lack of fine motor or gross motor coordination, clumsiness, loss of balance and falls, difficulty walking, etc.
• Vision: Blurred or double vision, blindness, loss of vision in part of the visual field, etc.
• Speech: Such as slurred speech.
• Non-Specific Symptoms: Various other symptoms are possible such as fatigue (quite common), heat sensitivity, dizziness, impaired thinking, etc.

The progression of these types of symptoms and the course of the disease throughout a patient's life can vary quite considerably as there are many different types of multiple sclerosis.

Unfortunately, many of the symptoms associated with multiple sclerosis can be caused by many different nervous system diseases. Therefore, diagnosis of MS can sometimes be difficult. However, while any one attack of MS may have several potential causes, a thorough work-up can lead to the correct diagnosis.

Types of Multiple Sclerosis:

There are several types of multiple sclerosis varying primarily in the course of the disease throughout a patient's life. These differences in the natural history of the disease can be quite dramatic. It is unclear what determines which sub-type a given patient will have. Likewise, once a patient presents with early signs of multiple sclerosis it can be initially difficult (or impossible) to predict which progression they can expect in the future. It may only be once considerable time has passed, and the course of the disease and its related symptoms has been observed, that a given patient can be classified under one of the general types.

In a general sense, there are four sub types of multiple sclerosis, distinguished by the course the disease takes in that patient:

• Relapsing-remitting: This is the most common form of MS, particularly in the early course of the disease. Some patients who initially have relapsing-remitting MS later develop more progressive forms. It is characterized by periodic acute attacks or exacerbations of symptoms. These attacks can evolve over several days to weeks. Following the acute period, the symptoms can persist or can improve partially or fully. This recovery can take weeks to months. In between the acute attacks, the symptoms do no get worse.
• Primarily-progressive: Overall, this type is less common, only occurring in around 15% of patients, most commonly in people who present with the disease later in life (after around 40 years of age). It is characterized by a steady progression of symptoms and disability without the acute attacks and relapses that are seen in the more common relapsing-remitting type. These patients have a gradual worsening of central nervous system function and do no have periods of improvement.
• Secondary-progressive: In some patients who initially present with a relapsing-remitting form of MS, symptoms may become progressive, like in the primarily-progressive form described above, at some point in their life. These patients first have some period of relapsing-remitting MS, which can last anywhere from months to many years or decades. They then begin progressing without the acute attacks and remissions associated with that form.
• Progressive-relapsing: The least common form of MS, these patients have what amounts to be a superimposition of relapsing-remitting MS on top of primarily-progressive MS. They will experience gradual, steady progression of symptoms and disability but will also experience superimposed acute attacks where their symptoms get acutely worse and may or may not be followed by some improvement.

Multiple Sclerosis Diagnosis:

Multiple sclerosis diagnosis can initially be tricky because it can affect any part of the central nervous system and can therefore present quite differently in each individual patient. There is no single test which confirms the diagnosis of MS. Therefore there are various criteria which are evaluated to assess whether a patient's symptoms and progression are consistent with the disease. Typically, this process of diagnosis is undertaken by a neurologist.

Some disease that can initially be misdiagnosed as MS or confused with MS include vasculitis, migraine headaches, multiple strokes, vitamin deficiencies, lupus or brain infections.

Making the Diagnosis:

First of all, a good medical history and thorough neurological examination can help your physician identify those aspects of the disease which are consistent with MS. Details of the onset, progression of the symptoms and types of symptoms are particularly important parts of the medical history which can help distinguish multiple sclerosis from other diseases.

In addition, there are several tests or imaging studies which help to make the diagnosis or rule out other similar diseases. These can include brain and spine MRI, spinal taps (lumbar puncture), evoked potentials and blood tests.

With all of this clinical information gathered, there are several criteria which are then used to arrive at the diagnosis:

• Onset of disease: typically occurs between 20 and 50 years of age.
• Objective signs and symptoms referable to disease of the brain and/or spinal cord (peripheral nerve disease is not caused by MS).
• MRI evidence of two or more lesions in the brain and/or spinal cord.
• A history of two or more episodes lasting at least 24 hours and occurring at least one month apart (particularly for relapsing-remitting forms of the disease).
• No other explanation for the symptoms

Only if these criteria are met and a full work-up has been done can a physician make the working diagnosis of multiple sclerosis.

Multiple Sclerosis Treatment:

Although there is no cure for MS, multiple sclerosis treatment aims to improve each patient's quality of life by preventing attacks, slowing disease progression, minimizing symptom severity and duration and treating symptoms.

For example, several drugs are used to prevent or minimize symptoms. These drugs are generally immune suppressing or modulating drugs, which inhibit or modify the way the immune system works, hopefully preventing or reducing the severity of the autoimmune attacks on the central nervous system. Some of these drugs are used chronically to prevent exacerbations and delay progression while others are used acutely (such as steroid drugs like prednisone) during attacks to lessen symptom severity and duration.

Additionally, some treatment is simply symptomatic, meaning that it aims at making patients more comfortable with their symptoms. This includes pain medications for patients with pain. Many patients complain of muscle spasms and there are various anti-spasmodics which can help with this. Some patients may experience urinary incontinence and there are some drugs which can improve bladder control.

Finally, there are a number of procedures which are sometimes employed. Plasmapheresis is a procedure which attempts to minimize the antibodies in the blood, hopefully getting rid of some of the antibodies which may be involved in the autoimmune disease. Although it is controversial it may be recommended in some cases. Other types of multiple sclerosis treatment are aimed at a specific symptom. For example, in patients with severe tremor a deep brain stimulator procedure may be recommended to help control the tremors.

Cure for Multiple Sclerosis:

Unfortunately, there is no cure for multiple sclerosis. As with most autoimmune type diseases, no cure can completely eradicate the problem. Multiple sclerosis is a chronic disease, which, once diagnosed, continues throughout the patient's life. However, there are many sub-types of the disease with different natural histories and disease courses. While any given patient may experience periods of remission during which they have no new symptoms, the disease will typically rear its ugly head again at some point in the future.

However, although there is no absolute cure, there are a number of treatment options for MS which help to control or modify the symptoms in some patients. They may slow the progression of the disease and improve the quality of life in many patients. In general, multiple sclerosis treatment consists of various forms of immune suppression, drug treatments which suppress the activity of the immune system and thus lessen its attack on the myelin sheath in the central nervous system.

Multiple Sclerosis Medications:

There are many multiple sclerosis medications used to treat the symptoms of MS. Most are some form of immune suppressing or altering drugs which decrease or modify the activity of the immune system. While none represent a cure for MS, they can slow the progression of the disease, lessen symptoms, delay disability and improve the quality of life for many patients.

Some medications used to treat MS include:

Avonex (interferon beta-1a)
Betaseron (interferon beta-1b)
Copaxone (glatiramer acetate)
Novantrone (mitoxantrone)
Rebif (interferon beta-1a)
Tysabri (natalizumab)

Additionally, in acute attacks of MS, steroid medications, such as prednisone or hydrocortisone, are used to suppress the immune system and limit the duration and severity of the attack. However, because of their side effects they are not typically used long-term for the chronic control of the disease.

In addition to these immune suppressing or modulating drugs, a number of multiple sclerosis treatments are aimed at simple symptomatic control. For example, medications may be prescribed for pain, muscle spasms and bladder control.