Motor Neurone Diseases
What are Motor Neurone Diseases?
The motor neurone diseases (MND) are a group of progressive neurological disorders that destroy motor neurons, the cells that control voluntary muscle activity such as speaking, walking, breathing, and swallowing. Characteristic symptoms of MND include gradual weakening, wasting away, and uncontrollable twitching of the muscles; spasticity or stiffness in the arms and legs; and overactive tendon reflexes. Sensation, intellect, memory, and personality are not affected in MND. In some types of MND, such as amyotrophic lateral sclerosis (ALS, commonly called Lou Gehrig’s disease) muscle weakness is progressive and eventually leads to death when the muscles that control breathing no longer work. Other types of MND progress slowly and last over a lifetime. MND occur in adults and children, and are more common in men than in women. In adults, symptoms usually appear after age 40, and may be similar to those of other diseases, making diagnosis difficult. In children, particularly in inherited forms of the disease, symptoms are present from birth. Inherited forms of MND are caused by genetic mutations or deletions that cause degeneration of motor neurons. Hereditary MND include a group of childhood disorders known as the spinal muscular atrophies. Nonhereditary (also called sporadic) MND are caused by unknown factors, although scientists think environmental toxins or viruses could act as disease triggers. Nonhereditary MND include ALS, progressive bulbar palsy, pseudobulbar palsy, primary lateral sclerosis, progressive muscular atrophy, and post-polio syndrome. There are no specific tests to diagnose the MND.