OVERVIEW Multiple sclerosis (MS) is a disorder of the sheath that covers nerve fibers in the body. Made up of fat called myelin, these sheaths enable electrical impulses to be conducted along the nerve fiber quickly and accurately. When the myelin sheath is damaged, it distorts the normal way in which nerve impulses travel. The term sclerosis refers to the areas of scarring which occur following this damage.
MS can occur in different forms: progressive MS means the condition gets progressively worse over time; relapsing-remitting MS causes flare-ups (relapses) alternating with periods when the symptoms are stable (remission); a secondary progressive form affects about half of patients who start off with relapsing-remitting MS; primary progressive means the person experiences steadily worsening symptoms from the outset; and benign MS is characterized by occasional relapses with good periods of recovery in between.
INTRODUCTION Multiple sclerosis is the most common cause of serious physical disability in working age adults. MS is usually diagnosed between the ages of 20 and 40. It can occur in older age groups but is less common in the under 20s. More than twice as many women than men are affected by MS. About 1 in 500 people are at risk of developing the disease.
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It is an auto-immune disease – that is MS is the result of the person’s own immune system attacking the myelin sheaths. An interesting finding is that those living close to the equator are less susceptible to developing MS.
MS produces symptoms which vary significantly from person to person depending on the site and extent of damage. If sensory nerves are affected then symptoms will include abnormal sensations, tingling, pain or burning. Sensory nerve damage can also produce problems with the eyes such as double vision or blurring, and other problems including vertigo or dizziness.
In contrast, damage to motor nerves can produce symptoms of weakness, difficulty walking, balance problems, tremor, stiffness, unsteadiness and fatigue. It can also lead to difficulty with control of urination or bowel control.
Your emotions, memory and concentration may also be affected.
CAUSES, SIGNS, SYMPTOMS AND DISGNOSIS The exact cause of MS is unknown, and multiple genetic causes may emerge. Environmental and infectious disease triggers are also being studied, including a possible relationship between low levels of Vitamin D and MS. This might help explain the finding that people living in warm climates seem to be at lower risk of developing the condition.
The initial symptoms experienced by someone with MS depend on the location of the myelin sheath scarring. So if the optic nerve is affected then blurring of vision may be the first symptom to appear. Here are some of the more common symptoms: Fatigue: Extreme tiredness not related to the level of activity or sleep/rest Blurred/double vision or loss of vision. Weakness of the limbs: especially in the legs or hands Balance problems: veering to one side or bumping into things Altered feelings in the body: numbness, pins and needles, burning or sensitivity to heat. Muscle spasms, stiffness and tremors Bladder symptoms: an urgent need to pass water Speech and swallowing difficulties Memory, reasoning and concentration difficulty
A diagnosis of MS should be made by a consultant neurologist. It can be a difficult diagnosis to make as there is no one, single test for the disease. The consultant will put together your symptoms, the clinical findings of a detailed neurological examination and the results of tests in reaching a diagnosis.
Tests include blood tests to rule out other possible causes for your symptoms such as a poorly functioning thyroid gland, anaemia or a Vitamin B12 deficiency.
An MRI scan produces good images of the brain and spinal cord. It can identify areas of scarring, which show up as areas of white or light grey on the scan.
Lumbar puncture is a test that involves placing a needle in the back and taking some fluid from around the spine. This is then analysed in the laboratory to see if characteristic features of MS are present.
A myelogram is an x-ray of the spinal cord taken after dye has been injected into it. Any obstructions to the flow of dye along the spinal cord may help diagnose other causes for the symptoms other than MS.
Visual evoked responses (VER) are electrical tests of vision which can detect any delay in messages travelling between the eye and the brain.
PREVENTION/TREATMENT
While there is no known primary prevention for MS, having a healthy lifestyle with good diet, exercise and stress reduction can alleviate some of the symptoms and help delay further disability.
Treatment varies but can be broadly divided into managing symptoms, reducing inflammation during relapses and specific therapies aimed at changing the course of the disease – disease modifying treatment (DMT)
The choice of treatment also depends on the type of MS you have. Progressive forms of the disease do not respond well to anti-inflammatory drugs or DMT. However the inflammation associated with relapsing – remitting MS responds to steroids and DMT.
Steroids may be given either orally or intravenously. They are good at speeding up recovery from a relapse but do not influence the overall progression of the disease.
DMT has been shown to reduce the number and severity of MS relapses and is a standard treatment for relapsing –remitting MS.
First –line DMTs licensed in Ireland include two forms of beta interferon and the drug glatiramer acetate. Second – line options include natalizumab and fingolimod. There are a number of drugs in various stages of development offering the possibility of even more effective treatment in the future. You may be offered the opportunity to participate in a clinical trial by your consultant.
Other drugs are used to treat specific symptoms such as tremor, muscle spasm and psychological problems. The use of physiotherapy and occupational therapy also help to promote and maintain physical independence and functional ability.
Fatigue is one of the most common symptoms of MS, occurring in about 80 per cent of people. It can significantly interfere with a person’s ability to function and may be the most prominent symptom in a person who otherwise has minimal activity limitations. The drug amantadine may help alleviate fatigue.
Occupational therapy intervention can provide a range of strategies to cope with fatigue. These include advice on the simplification of tasks at work and home, advice on fatigue and stress management, relaxation training and the provision of assistive technology.
Physiotherapy can help by teaching energy-saving ways of walking and helping to develop a regular exercise programme.
USEFUL RESOURCES
The Multiple Sclerosis Society of Ireland Information Line 1850 233 233 www.ms-society.ie British National Health Service www.nhs.co.uk/conditions/ms
The Mayo Clinic www.mayoclinic.org/.../multiple-sclerosis
Dr Muiris Houston is a general practicioner