Disease of the Month: Motor Neurone Disease

The Theory of Everything, the 2014 British film depicting the life of theoretical physicist Stephen Hawking, highlighted the plight of a Motor Neurone Disease sufferer and made the general population more aware of this condition.

Motor Neurone Disease (MND) is a progressive disease that attacks both the upper and lower motor neurones and gradually prevents messages from reaching muscles so they don't know what to do.

First described by the French neurologist, Jean-Martin Charcot in 1874, the term is generally used for a number of related diseases affecting the motor neurones.

The disease can occur in adults of any age, but most commonly after the age of 40 and predominantly between the ages of 50 and 70. There are about 5,000 people living with the condition in the UK at any one time with men being affected twice as often as women.

Although MND is a devastating and often rapidly progressive disease, it is still a comparatively rare condition affecting around two in every 100,000 people in the UK each year. There are about 5,000 people living with the condition in the UK at any one time.

Motor neurones are nerve cells that carry messages from the brain and spinal cord to control and stimulate various muscles within the body. These nerve cells are divided into two groups: upper motor neurones (in the brain) and lower motor neurones (in the brainstem at the base of the brain, the spinal cord, and in the arms, legs and torso).

Symptoms

Motor Neurone Disease leads to weakness and wasting of muscles causing loss of mobility in both upper and lower limbs, plus difficulty speaking, swallowing and breathing.

Depending on the type of disease you have, the first muscles affected are usually in the hands, feet and mouth. However, the symptoms of MND can vary enormously from person to person, from the presenting symptoms, rate of progression, to the survival time after diagnosis.

As well as mobility problems, the most common symptoms include;

Speech and communication issues
Swallowing difficulties resulting in:
problems with eating and drinking
Saliva pooling in mouth
Coughing and choking
Cognitive changes, such as difficulties with memory, language or concentration
Breathing problems
Muscle cramps, pain and spasms
Stiffness in joints
Bowel and urinary problems are not usually associated with MND, but an individual may have difficulties due to changes in diet and immobility.

Types of MND

There are four main types of Motor Neurone Disease

Amyotrophic Lateral Sclerosis (ALS)

This is the most common type, with both upper and lower motor neurones affected.

This disease is characterised by weakness and wasting of muscles in the limbs and the first symptoms may be tripping up or dropping things.

Average life expectancy for ALS is usually between two and five years from onset of symptoms. However, it is interesting to note that Stephen Hawking, who was diagnosed with type ALS when only a young man, has lived with his symptoms for over 50 years.

Progressive Bulbar Palsy (PBP)

This form affects about a quarter of people diagnosed with Motor Neurone Disease and again involves upper and lower motor neurones. Symptoms can include difficulty swallowing and slurring of speech.

Average survival time is between six months and three years from onset of symptoms.

Progressive Muscular Atrophy (PMA)

This affects a much smaller number of individuals and mainly causes damage to the lower motor nerves. Early symptoms may just be weakness or clumsiness of the hands with a life expectancy of more than five years.

Progressive Lateral Sclerosis(PLS)

This is a rare form of MND, causing mainly weakness in lower limbs, although some sufferers may experience clumsiness in hands and speech problems. Life expectancy can often be normal, however, PLS can develop into ALS with survival time considerably reduced.

Causes

The cause of Motor Neurone Disease is still not fully known, however, it is thought that certain chemicals or structures that only occur in motor nerves are damaged in some way.

The reason why these nerves become damaged is not clear, but it is believed that there are a number of different triggers, both genetic and environmental.

5-10% of cases of Motor Neurone Disease are inherited. However, the gene that is faulty can differ from one affected family member to another and so far the exact gene that has mutated can only been identified in about 70% of individuals with inherited MND.

Most people who develop Motor Neurone Disease have 'sporadic' MND - this means there is no family history, and it is unlikely to develop in other family members.

As already mentioned, little is known about what causes sporadic MND, but several possible factors have been suggested, including exposure to chemicals, injuries, smoking, military service, and taking part in high levels of exercise.

However, research has so far failed to find any conclusive evidence of this or identified one specific underlying cause and it is considered that several different factors and triggers are involved.

Diagnosis and Tests

There are no precise diagnostic markers for Motor Neurone Disease as presenting symptoms differ from person to person, plus they are generally similar in nature to other neurological conditions. Therefore, the tests carried out are usually performed to eliminate other causes.

For example, the damage caused by MND does not show up on an MRI scan, however, it can eliminate other conditions such as Alzheimer's, Parkinson's and Multiple Sclerosis.

Blood tests are taken to check for a rise in an enzyme called creatine kinase, which can indicate damage and breakdown in muscle. However, this rise can also occur in other conditions.

Nerve conduction tests and Transcranial Magnetic Stimulation (TMS) measure the speed and activity of nerves carrying electrical signals. If abnormal, these results can help in the diagnosis process.

One important test is Electromyography (EMG), sometimes called the ‘needle test'. Fine needles are used to record the nerve impulses within certain muscles. The muscles tested are usually in the limbs and the bulbar, or throat, muscles.

Not only can the test detect the loss of nerve supply, but also the EMG can show abnormalities in the muscle even when that particular muscle is unaffected.

Treatment

Currently there is no cure for Motor Neurone Disease. Medication can only slow down the progression of the disease or help the management of symptoms.
Riluzole has been shown to slow down the progress of the disease by a few months and is used in the ALS form of the disease.

Muscle relaxants can help reduce the flow of saliva and treat muscle cramps.
Anti-inflammatory medicines and painkillers can help reduce pain and discomfort.
Complementary and occupational therapies such as massage, physiotherapy, reflexology and speech therapy can also help to provide a better quality of life

Research

Continuing research improves our understanding of the disease. Faulty genes continue to be identified and stem cell research is undertaken to try to find ways for the body to produce new motor neurones.
Clinical trials are also undertaken to try to improve treatment.

Underwriting considerations

Terms are generally not offered for applicants diagnosed with MND and those with a family history may have a small rating applied or Motor Neurone Disease excluded from critical/serious illness and disability cover.

Fergus Bescoby is underwriting development manager at VitalityLife