What is MND?
MND represents a family of closely related disorders, of which Amyotrophic Lateral Sclerosis (ALS) (also known as Lou Gehrig’s disease) is the most common. This collection of neurodegenerative disorders are typified by the progressive damage and ultimately death of the nerves (motor neurons) in the brain and spinal cord that control the muscles responsible for voluntary movement. As a result, the transmission of messages to muscles in the face, throat, chest, and limbs are interrupted to varying extents and muscle wastage and spasticity occur. There is no cure for MND but treatments are available which help to alleviate the symptoms.
Symptoms and types of MND
In the early stages, muscle weakness might only be apparent in one limb but as the condition worsens many muscles for the important activities of walking, gripping, swallowing, speaking and breathing can be affected.
Although they are all eventually similar as they get progressively worse various subtypes of MND are recognised of which the main types are:-
- Amyotrophic lateral sclerosis (ALS). About 8 out of 10 people with MND have this type which usually starts with weakness and stiffness in the hands and feet. Life expectancy is 2 to 5 years.
- Progressive bulbar palsy (PBP). About 2 out of 10 people have this type which initially affects the muscles used for speech, chewing and swallowing. Life expectancy is 6 months to 3 years.
- Progressive muscular atrophy (PMA). Few people are affected by this type which at first causes weakness but not stiffness in the small muscles of the hands and feet. Most people live for longer than 5 years after the onset of their symptoms.
- Primary lateral sclerosis (PLS). A rare condition mainly causing weakness in the leg muscles but some people might have hand or speech problems. Life expectancy is unaffected providing ALS does not develop.
What causes MND?
It is not known what causes MND. Usually, there is no family history of the condition, and it is most unlikely to develop in other family members. However, in about 10% of cases, more than one member of the family has either ALS and/or frontotemporal dementia. For no obvious reasons research has revealed a higher incidence of MND amongst footballers, farmworkers, and the inhabitants of Guam. Amongst the environmental factors which might be involved are exposure to chemicals, stressful lifestyles such as military service, head & leg injuries, smoking, and excessive exercise.