WHAT IS MOTOR NEURONE DISEASE?

The brain is linked to the rest of the body by nerves (neurones) which have been likened to electrical wiring; some carry impulses to the brain (the sensory nerves) while others carry messages from the brain to the muscles, to make the muscles work and contract - these are called the motor nerves or neurones. In MND these motor nerves degenerate so that the muscles supplied by them lose their strength.

The illness is not infectious and normally affects people over 40 years of age, most commonly between 50 and 80 years.

The number of people who will develop MND in one year is approximately 2.2 per 100,000 of the population (incidence): this means that about I00 people develop this condition in Scotland every year.

There is a small subgroup of people with MND (about 5%) in which the disease does seem to have run in the family, but in the vast majority of people, there is no chance of the children of people with MND being affected.

The disease will present in different ways depending on the location of the nerve cells involved. Doctors commonly use three main terms for Motor Neurone Disease but there is considerable overlap among the three forms as the disease progresses.

It must be stressed that MND affects individual people differently and not everyone will suffer all the symptoms. The rate of progression of the disease will also be individual to each person affected.

Amyotrophic Lateral Sclerosis

The most common form - about two thirds of those affected. This term (ALS) is used instead of MND in the USA and Canada, and some other countries. Main symptoms include muscle weakness and stiffness. Weakness commonly develops in the hands or feet, so that the first symptoms may include tripping when walking, or dropping things.

Progressive Muscular Atrophy

A less common form (about 8% of those diagnosed) PMA often starts in the small muscles of one hand, followed by weakness and wasting of other muscles.

Progressive Bulbar Palsy

This type of MND involves the muscles which control speech, chewing and swallowing (the bulbar muscles). Early symptoms are slurring of speech, and some difficulties with chewing and swallowing certain foods. Speech may deteriorate so that other ways of communication may be used. For some people weakness of other muscles may develop.

How does the disease develop?

In the early stages of the disease the symptoms and signs may be very slight. There may be spontaneous twitching of the weakened muscles (fasciculation), general fatigue, and loss of weight. Other early features may include cramp in the muscles of the limbs, abdomen, and chest, and jerking of an arm or leg while at rest. There may be slight difficulty in speech or swallowing, and shortness of breath in some people where the breathing muscles are weakened.

Because MND is a progressive disease, muscle weakness becomes worse with time, leading to loss of function, and gradual loss of mobility when the legs are affected. Help and support with activities of daily living will be needed. Stiffness of joints may cause discomfort.

In some people affected by MND there is a tendency to cry or laugh rather easily. This can be embarrassing at the time but does not mean that the affected person has developed a mental illness. It is part of a condition called pseudobulbar palsy, caused by MND.

The muscles weakened by MND do not recover, but there may be periods of weeks or months where the illness does not seen to progress.

What is not affected?

MND does not affect the senses ( touch, taste, sight, smell, and hearing) and the sense of feeling in the affected limbs remains normal. intellect and memory are not usually affected although in a very few individuals some deterioration may be experienced.

Bladder and bowel function remain normal, so incontinence is not a feature; however, immobility may disturb bowel and bladder function later in the illness.

Sexual desire and function are not directly affected. It is important to underline that the person with Motor Neurone Disease is, and will be fully in control of his or her intellectual faculties, feelings and emotions. Although the affected person may not be able to communicate easily to carers as the disease advances, it is important to take account of this and to allow time for slower methods of communication, such as electronic equipment, to enable the person to make decisions for himself or herself.

How is the diagnosis made?

There is no specific test for MND but tests are usually carried out to confirm the diagnosis by eliminating other possible conditions. Diagnosis may be difficult because the pattern of symptoms varies between individuals, and may be similar to those seen in other conditions.

The Neurologist (who usually makes the diagnosis) will probably arrange for a number of specialised tests such as Electromyogram (EMG). This involves electrical tests of the nerves using small needle electrodes. Scans, blood tests, and other specialised X-rays may also be used to confirm the diagnosis.

How is the disease treated?

Motor Neurone Disease has been known and recognised for more than 200 years, and as yet there is no treatment which provides a cure. However, many of the symptoms can be helped with the proper combination of medical treatment, specialised equipment, and psychological support.

Medication can be given to help with cramps, pain and stiffness, and with excessive salivation. Constipation can be helped with laxatives and diet change. Practical equipment is available to assist with splinting weak joints, mobility problems and communication.

A range of professionals are employed by the Health Service and Social Work Departments who can be called on as necessary to meet changing needs as the disease progresses.