Definition

MS is a chronic disease which occurs in the brain and spinal cord. It is the principal member of a group known as demyelinating diseases. It is the result of damage to the myelin sheath surrounding the axons of the nerve fibres in the central nervous system. The myelin is arranged in segments all along the nerve and the spaces between each myelin sheath are called the nodes of Ranvier. The myelin segment is called the internode. This arrangement allows for rapid and efficient axonal conduction by the process of saltatory conduction whereby the signal spreads rapidly and smoothly from one node of Ranvier to the next. If the myelin is lost or damaged, the insulation is damaged and the action potential is no longer conducted along the nerve, although the nerve itself is relatively undamaged.

It has been found that the central nervous system is able to overcome small areas of axon loss by finding ways to reroute messages around an area of damage through undamaged nerve cells. This ability to adapt in areas of damage is called plasticity. If the area of damage becomes too large, this rerouting process is no longer able to compensate and messages to or from that part of the central nervous system are permanently blocked, resulting in symptoms that do not improve. There seems to be a mixture of both grey and white matter affected by the demyelination process [1].

Incidences

MS has a peak incidence between 25 and 35 years and is twice as common in women as men.

Mortality

It appears that only about half the patients suffering from MS eventually die of causes related directly to it. Respiratory disease or cardiovascular complications, mainly brought about by demyelinating lesions, involving brain regions that regulate cardiorespiratory activity, could be considered as the immediate cause of death. But poverty of movement, trauma or even poor nursing care are also problems. The standardized mortality ratio in a recent study indicated that MS sufferers were almost three times as likely to die prematurely compared to the general population [2] but MS was not always given as cause on the death certificate.

Risk factors

It is now well established that there is a familial tendency to MS, although no clear pattern of inheritance has been found [3, 4]. Between 10% and 15% of patients with MS have an affected relative, a higher figure than could be predicted from population prevalence.

Differential diagnosis

Early signs and symptoms will often include vague feeling of ill health for several years preceding diagnosis. Relatively minor discomforts, aches, pains and general lethargy, all easily dismissed by the patient as being trivial, can mount up steadily until a doctor is consulted. It is also important to remember that many people diagnosed with MS remain mobile and can live a near-normal life without the need to see a physiotherapist or an acupuncturist.

Probably the most common single symptom is an acute or subacute loss of vision in one eye, rarely both.

Tests

The diagnosis of MS is not an easy one to make and relies more on elimination of other causes than a direct confirmation.

MRI scans can be used to reveal lesions or plaques in the brain and a lumbar puncture may be done to evaluate the cerebrospinal fluid. MS sufferers tend to have a raised white blood cell count and abnormal levels of immunoglobulin.

Pharmacology

Many MS patients do not require drug therapy; however, it is an incurable condition, and in order to manage acute episodes or specific symptoms some medication may be introduced.

Drugs to modify the disease are aimed at reducing the frequency and severity of relapses. Most commonly used are forms of interferon, given intrathecally, intramuscularly or subcutaneously. Interferon has antiviral and immunomodulatory properties and is used because it is thought that MS may have a viral origin.

The mechanism of action of interferon-β1b in MS is not clearly understood, but is thought to involve immunoregulatory activities, including enhancing the suppressor activity of peripheral blood mononuclear cells. In a recent study looking at patients with a single clinical event suggestive of MS, the relative risk of clinically definite (CD) MS was reduced by 41% in those receiving interferon-β1b 250 μg every other day for 3 years (early-treatment group) compared with patients who were initially randomized to placebo then switched to interferon-β1b 250 μg every other day at the end of 2 years or at the onset of CD MS (delayed-treatment group) (P < 0.01). [5]. Thus there is some evidence that early doses of this particular type of interferon may be helpful in preventing further development of symptoms in some patients, but much more work is needed [6].

Surgery

Surgery is not commonly used in MS but in cases of very severe tremor deep-brain stimulation can be tried with implantation of a device within the brain, as in Parkinson’s disease. In cases of disabling or painful spasticity a catheter or pump can be surgically placed in the lower spinal area to deliver a constant flow of medication, such as baclofen (Lioresal).

Fatigue

Contributing factors such as loss of sleep, poor diet or lack of aerobic exercise will be assessed.

Weakness and cardiorespiratory fitness

Patients are encouraged to undertake exercise targeted to their motor problems, allowing for any mobility problems.

Spasticity and spasms

Simple causative problems or aggravating factors such as pain or infection should be tackled. Passive stretching can be applied to the affected muscle groups and often families and carers are taught how to do this.

Contractures affecting joints

Specific positioning when at rest and gentle stretches should be continued to prevent contractures. Again, teaching the family is helpful.

If there is no response then splinting and serial casting may be tried.

Ataxia and tremor

Treatment techniques similar to those used in Parkinson’s disease may be helpful. Pharmacological support may eventually be necessary.

Sensory losses, including visual problems

Where these affect mobility and daily activities, solutions will be sought, involving new ways of doing things.

Pain and other problems