Motor Neuron Disease
Motor Neuron Disease.
Description, Causes and Risk Factors:
Motor neurones are specialized nerve cells that control important voluntary muscle activity, such as walking, speaking, breathing, and swallowing.
Motor Neuron Disease (MND) is the name given to a group of closely related diseases affecting the motor neurones, which are the nerves controlling muscles. Upper motor neurones go from the brain to the spinal cord and lower motor neurones go from the spinal cord to the muscles. Motor neuron disease is a fatal and progressive neurodegenerative disease.
The term `Motor Neurone Disease' is also used to describe variants of the disease - namely progressive muscular atrophy (PMA) and amyotrophic lateral sclerosis (ALS) which includes Progressive Bulbar Palsy (PBP). ALS, which is characterized by both upper and lower motor neurone signs, is the most common form of MND, accounting for 65% to 85% of all cases. Adult-onset MND usually starts insidiously with symptoms and signs including stumbling, foot drop, weakened grip, slurred speech, cramp, muscle wasting, twitching and tiredness.
MND is most prevalent in the age range of 40 to 70 years and about 20 per cent more common in men than in women.
The cause of the disease is still unclear. About 10% of MND cases are inherited. Of those, 20% are caused by mutations in a gene on chromosome 21 called SOD1 (super oxide dismutase 1). Over 60 mutations or structural defects of the SOD enzyme have been found which alter the enzyme's ability to protect against damage to motor neurons.
Research also shown that an excess of glutamate (a major nervous system chemical messenger) may be responsible for nerve damage. Glutamate plays an important role in the fast transmission of nerve signals. When too much is present it can become 'excitotoxic', which means it's overactive and overstimulating. This is thought to damage key areas of the brain and spinal cord, resulting in the symptoms of MND.
Some cases of motor neurone disease may be caused by underlying problems with the gila cells, which mean that the motor neurones no longer receive the support and nutrition that they require to function normally.
There is some evidence that in cases of MND, neurotrophic factors (a type of protein) are not produced in the correct way, which may make the motor neurones more vulnerable to damage and affect their function.
Early symptoms include fasciculations(twitching), cramps in the affected muscles andgeneral fatigue. Spasticity (stiffness) and jerkingof arms and legs may also occur.
The weakness in MND often starts in the hands orfeet and because MND is a progressive disease,the muscle weakness becomes worse with timeleading to loss of function of limbs and weaknessand wasting of the muscles of the trunk and neck.The person therefore may become quite immobileand require help in performing activities of dailyliving.
Other symptoms may include:
Difficulty walking or holding objects.
Emotional responses trigger easily.
Depression and anxiety.
Fatigue and weakness.
The diagnosis of MND is oftenclinically difficult, and sometimesit is necessary to review a personfor some time before the diagnosisbecomes relatively certain. Severalother neurological conditionsresemble MND, especially in theearly stages, and need carefulexclusion.
The diagnosis can be assistedthrough a range of tests,including some which eliminateother conditions. Nerveconduction studies (NCS) andelectromyography (EMG) areoften performed and may help inestablishing the diagnosis. NCSinvolve analysing neural functionby electrical stimulation of nervesand recording muscle activity.EMG consists of inserting a needleelectrode into various muscles tomeasure their electrical activity.
Laboratory Tests may include:
Liver function test.
Complete blood and urine tests.
If you are diagnosed with motor neurone disease (MND), you will be introduced to a team of health professionals who will be involved in your care. It is not possible to prevent MND from developing. Treatment can slow down the progression of the disease for some people and occupational therapy can help to overcome difficulties.
Treatment involves a package of measures tailored to the individual. Physiotherapy helps improve the flexibility of muscles and joints.
Pharmacological Treatment: Riluzole is the only medication that is available to treat MND directly. Riluzole reduces the amount of glutamate in the body, which can slow the progression of MND. Side effects include nausea, vomiting, weakness, rapid heartbeat, drowsiness, headaches, and dizziness.
When secondary problems arise, then appropriate treatments can be given. For example, depression can be treated with antidepressant medication
Disclaimer: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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