Multiple Sclerosis explained

Multiple sclerosis is a disease of the central nervous system that affects twice as many women as men. Find out about the symptoms, diagnosis and treatment

Multiple sclerosis (MS) is a chronic, sometimes disabling, disease of the central nervous system affecting an estimated 2.5 million people worldwide. In the UK, about one per 1,000 of the population is affected by MS. It affects twice as many women as men. It is principally a disease of young people, with an average age of onset around 30 years of age.

In multiple sclerosis, the myelin sheath - the fatty insulation surrounding nerve cells in the brain and spinal cord - becomes inflamed. Myelin, which acts like the rubber insulation found in an electric cable, facilitates the smooth transmission of high-speed messages between the brain and the spinal cord and the rest of the body. As areas of myelin are affected, messages are not sent efficiently or never get through.

Eventually there is a build-up of scar tissue (sclerosis) in multiple places; hence the disease is termed multiple sclerosis. These plaques or scarred areas, which are only a fraction of inch in diameter, can interfere with signal transmission. The underlying nerve may also be damaged, further worsening symptoms and reducing the degree of recovery experienced. The disease can manifest itself in many different ways. Sometimes the diseased areas cause no apparent symptoms and sometimes they cause many; this is why the severity of problems varies greatly among persons affected with MS.

Misguided attack
MS is classified as an autoimmune disease. In MS, the immune system - for reasons still not understood - attacks and destroys myelin and the oligodendrocytes (oligo-few, dendro-branches, cytes-cells) that produce it. Certain types of white blood cells called T-lymphocytes and killer T-cells appear to attack and consume myelin. Though the body usually sends in immune cells to fight off bacteria and viruses, in MS they misguidedly attack the body's own healthy nervous system, thus the term autoimmune disease. MS is similar to other autoimmune conditions such as rheumatoid arthritis and lupus. Multiple sclerosis usually strikes in the form of attacks or exacerbations. This is when at least one symptom occurs, or worsens, for more than 24 hours. The symptom(s) can last for days, weeks, months, or indefinitely.

Types of MS
The most common type of multiple sclerosis is relapsing-remitting and is characterised by periods of exacerbation followed by periods of remission. The remissions occur because nervous system cells have ways of partially compensating for their loss of ability. There's no way of knowing how long a remission will last after an attack - it could be a month or it could be several years. But disease activity usually continues at a low, often almost invisible, level and MS often leads to disability over time as the signal-transmitting portion of the cells - the axons - are damaged.

Other patients develop symptoms that persist and progress without remission and within ten years - this is called secondary progressive MS. Others have an initial minor attack of symptoms which appear to recover completely and do not return. This is called benign MS. The fourth type, primary progressive MS, affects ten per cent of patients and is charaterised by progressive neurological damage from the outset. [anchor tag]

Symptoms
Most commonly, multiple sclerosis starts with a vague symptom that disappears completely within a few days or weeks. Temporary weakness in a limb such as a leg can be a first sign. Ataxia (general physical unsteadiness), temporary blurring or double vision, difficulty urinating, and slurred speech are also symptoms that can appear suddenly and then vanish for years after the first episode or, in some cases, never reappear.

The symptoms of MS vary greatly, as does their severity, depending on the areas of the central nervous system that are affected. Most people suffer minor effects. The disease can, however, completely disable a person, keeping him or her from speaking and walking in the most extreme cases. The bodily functions that are commonly affected by MS are:

  • Vision
  • Coordination
  • Muscle strength
  • Sensation
  • Speech and swallowing
  • Bladder and bowel control
  • Sexuality
  • Cognitive function (ability to think and reason)

    Within each of these functions, a varying degree of dysfunction may occur. For instance, one person may suffer blurred vision while another may suffer double vision. Or one person may suffer from tremors while another will experience clumsiness of a particular limb. Here are some specific kinds of symptoms that can occur:

  • Fatigue: a debilitating kind of general fatigue that is unpredictable and out of proportion to the activity; fatigue is one of the most common (and one of the most troubling) symptoms of MS.
  • Visual disturbances: blurring of vision, double vision (diplopia), optic neuritis, involuntary rapid eye movement, (rarely) total loss of sight.
  • Balance and coordination problems: loss of balance, tremor, unstable walking (ataxia), dizziness (vertigo), clumsiness of a limb, lack of coordination.
  • Weakness: usually in the legs.
  • Spasticity: altered muscle tone can produce spasms or muscle stiffness, which can affect mobility and walking.
  • Altered sensation (paraesthesia): tingling, numbness, a burning feeling in an area of the body, or other indefinable sensations.
  • Abnormal speech: slowing of speech, slurring of words, changes in rhythm of speech.
  • Difficulty in swallowing (dysphagia).
  • Bladder and bowel problems: the need to pass urine frequently and/or urgently, incomplete emptying or emptying at inappropriate times, constipation, loss of bowel control.
  • Sexuality and intimacy difficulties: impotence, diminished arousal, loss of sensation.
  • Cognitive and emotional disturbances: problems with short-term memory, concentration, judgment or reasoning.
  • Pain: facial pain (such as trigeminal neuralgia), muscle pains.
  • Sensitivity to heat: this often causes a transient worsening of symptoms.

    So, while there are symptoms that are common to many people and most people with MS will experience more than one symptom, no one will have all of them. There is no typical case of MS. They are all different.

    Risk factors
    MS is twice as common in women as in men and more common among Caucasians than other races. Some populations, such as Eskimos and Bantus, rarely, if ever, are diagnosed with the disease. The incidence rate among Asian populations is very low. Research has shown that MS occurs more frequently in higher latitudes. In other words, the closer you are to the equator or the more tropical your climate, the less likely your chances of developing MS. The disease is five times more prevalent in the northern United States, Canada and northern Europe than in other parts of the world. But researchers don't know if this is due to genetic or environmental factors. The cause of MS is still unknown. Some researchers believe it could be caused by a virus, although it is unlikely that there is just one MS virus. Researchers do know that MS is not contagious. And while it is not an inherited disease, genetic susceptibility has a role. There is a higher risk for MS in families where it has already occurred. Children or siblings of a person with MS have a one per cent chance of developing the disease. The identical twin of a person with MS has a 33 per cent chance of developing MS. [anchor tag]

    Diagnosis
    Most people with MS begin experiencing symptoms between the ages of 20 and 40. But the initial symptoms may be vague, may come and go with no pattern or be attributed to other factors or conditions. For instance, a woman who experiences sudden bouts of vertigo once every few months may explain away the symptom by linking it to her menstrual cycle. Or, perhaps, someone who suddenly has a bit of blurry vision may see putting in too many hours at the office as the culprit.

    Diagnosing MS involves several tests and a lot of discussions with doctors. You will probably have a complete physical examination, a discussion of your medical history, and a review of your past and/or current symptoms. You should pay attention to any symptom suggestive of MS. Early diagnosis of MS is important because a new generation of treatments introduced in the 1990s can reduce the frequency and severity of MS attacks. In fact, new research has prompted doctors to change the diagnostic criteria in order to treat more cases of MS early.

    Magnetic resonance imaging
    In the past a diagnosis of MS required that the patient experience two separate 'attacks' - symptoms suggestive of neurological damage, such as blurry vision, numbness, tremors or difficulty with balance. The two attacks had to be different in type and separated in time, suggesting damage to two different areas of the central nervous system. The delay between a first and second attack meant that a conclusive diagnosis could take years.

    Today, doctors can use magnetic resonance imaging (MRI), introduced in the late 1980s, to scan the brain for lesions indicating early evidence of damage. An MRI is painless and non-invasive. If you need one, you will be seen in the radiology department. Lying on a table, on your back, the table will be pushed into a tube-like structure and your body will be exposed to a strong magnetic field. An MRI takes detailed pictures of your brain and, sometimes, spinal cord and is able to show any scarred areas.

    There is some evidence to suggest that the earlier MS is diagnosed and treated, the better. This evidence has prompted the formation of a panel of experts to recommend criteria for diagnosis of MS, namely one attack with clinical evidence of lesions on an MRI performed at least three months after the attack.

    Bear in mind that a normal MRI is not definitive evidence that a person does not have MS. About five per cent of MS patients have normal MRIs.

    Other diagnostic tests
    These may also contribute to establishing the diagnosis of MS:

  • Visual evoked potential tests, which measure the speed and efficiency of nerve signal conduction of visual messages of the brain and can also help detect lesions. These tests offer evidence of neurological scarring outside the brain. Evoked potential tests are painless and noninvasive. A physician or technician will place small electrodes on your head to monitor your brainwaves and your response to auditory, visual and/or sensory stimuli. The time it takes for your brain to receive and interpret messages is a clue to your condition.
  • A spinal tap, which tests the cerebrospinal fluid (fluid surrounding the brain and spinal cord) for substances that indicate strong immune activity in the central nervous system. Abnormalities of immune proteins in the CSF are seen in some 90 per cent of MS patients.
  • Blood tests, to rule out other potential causes of symptoms, such as Lyme disease and AIDS.

    Treatment
    Before the 1990s there was no treatment that could alter the course of MS. Steroids, which suppress the immune system, were used to treat exacerbations, but long-term use of these drugs is ineffective and produces severe side effects.

    The ABC drugs
    The outlook brightened with the introduction of Betaferon, the first disease-altering drug for relapsing-remitting MS. Two other medications, Avonex and Copaxone, followed in 1996. These three treatments, dubbed the 'ABC drugs', have revolutionised the way relapsing-remitting MS is treated. (Unfortunately, they have not been shown effective for patients with progressive forms of MS.)

    The ABC drugs do not stop MS entirely, but they do reduce the frequency and intensity of attacks and slow the progress of damage. Betaferon (interferon beta-1b) and Avonex or Rebif (interferon beta-1a) are biotechnology drugs based on a natural human protein that dampens immune system activity. The third disease-altering drug, Copaxone (glatiramer acetate), works by a different mechanism: it looks like myelin to the immune system and acts as a decoy. All three are injected drugs. Your doctor will instruct you or a caregiver on medication preparation and self-injection.

    Side effects include flu-like symptoms following the injection, which lessen over time. Rarer side effects include mild anaemia and elevated liver enzymes, which may indicate liver inflammation. Also allergic reaction, blood disorders, menstrual disorders, mood changes and convulsions.

    Note: Talk to your doctor if you experience any side effects from one of these drugs. There may be strategies you can use to quell the effects, they may abate in a few months, or you may be able to switch to one of the other two drugs and avoid the side effects. If you stop taking the drug, it may seem like there are no consequences, but MS damage can occur steadily and silently for long periods before the next attack.

    Other treatments

  • Steroids such as methylprednisolone are often prescribed to treat acute attacks of MS, whether the patient is taking an ABC drug or not. These drugs speed the recovery from the acute attack, but do not stop disease progression. After many attacks, steroids may no longer be effective. Long-term use of steroids also has many side effects, including ulcers, weight gain, acne, cataracts, osteoporosis and diabetes.
  • Chemotherapies that suppress the immune system broadly and were originally designed to treat certain cancers are sometimes used for progressing MS. Novantrone (mitoxantrone) was approved specifically for worsening relapsing MS and progressive MS in October 2000. Cyclophosphamide (Cytoxan) and azathioprine (Imuran) are used similarly. Novantrone can only be used for two to three years in a lifetime, because it may cause heart damage.
  • A process in which the antibodies are filtered from a person's blood called plasmapheresis may be successful in combination with immunosuppressants for short-term treatment of some progressive patients. For symptom management, doctors have an arsenal of medications. Each has varying side effects in varying degrees; however, your doctor should be able to find one that provides comfort and relief for almost any symptom you have.

    Non-medical strategies
    An MS diagnosis doesn't have to stop your life, but you will have to learn - and practise - strategies for managing fatigue and dealing with other temporary or long-term disabilities. Occupational therapists and physiotherapists can help you develop strategies and select assistive devices to navigate the workplace and home environment.

    Physiotherapy usually focuses on walking (including using walking aids correctly), balance and stability in standing, maintaining range of motion and functional strengthening. Occupational therapy focuses more on ways to accomplish specific everyday tasks at home and work, as well as energy management. Some programs also include techniques to improve memory and concentration. Symptoms that affect your memory and concentration may be the most painful to talk about. But acknowledging these symptoms and discussing them with your doctor and your family are the first steps towards getting them under control. The National Multiple Sclerosis Society can direct you toward support groups and publications that can help.

    Prognosis
    In 1890, a person diagnosed with MS was treated with herbs and bed rest, and life expectancy was five years. Eighty years later, in 1970, a person could expect to live, on average, 32 years after a definitive diagnosis was made. Today, life expectancy for those with MS is close to normal.

    Support groups
    The National Multiple Sclerosis Society www.nmss.org