Motor Neurone
Disease
Aetiology
Idiopathic Not
genetic but a possible genetic predisposition
Epidemiology
Prevalence of about 6 per 100
000 Onset
in middle or later life
Rare under 20 years most in
fifth and sixth decades
Pathology
Progressive degeneration of the motor nuurones in the
anterior horn cells motor
nuclei in the medulla
Upper motor neurones in the
spinal cord and brain stem and to some extent in the cerebral hemispheres.
Neurones supplying the
bladder and anal sphincter are usually preserved
Clinical
features
There are no sensory or
cognitive features
The disease has 3 onset
patterns however these are not aetiologically or pathologically different and
merge later on in the course of the disease
Progressive muscular atrophy
Wasting often begins in a
hand and works throughout the arm
Both sides are effected
sooner or later Cramps
may occur but there is no pain
Faciculation Loss
of reflex arcs
Progressive bulbar palsy
Dysarthria Dysphagia Nasal
regurgitation Choking
Amyothrophic lateral sclerosis
Muscle wasting, usually of
the arms, with pyramidal involvement, usually of the legs)
Treatment
Diagnosis
No specific diagnostics Clinical
diagnosis Electromyography
Symptomatic management
Riluzole Prevent
complications of immobility Prevention
of cramps
Prevention of aspiration
These patients are usually
well informed and are aware of the prognosis so require full
psychosocial/spiritual support
Death from pulmonary
infection and inhalation usually occurs in about three years.
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 in
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.
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.
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.
Amyotrophic
Lateral Sclerosis - Loss of upper and lower motor neurones
The
most common form - about two thirds of those affected. This term (ALS) is used
instead of MND in the
Progressive
Muscular Atrophy - Lower motor neurones only
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 - Cranial nerves are most severely affected
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.
Primary lateral sclerosis (upper motor
neurones only) is sometimes classified as a fourth presentation of the disease
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.