The Nervous System is a chain of a typical type of cells, called Neurons. These neurons transmit information from brain to other part of the body and from other parts of the body to the brain. These also pass information from surroundings to the body parts. Neurons processes the information and cause respective reactions in our body. Neurons consist of a long nerve fibre called, Axon. It helps in transmission of information to parts of the body in the form of electrical impulses. Due to its long and slender shape, it can conduct information away from the nerve cell. Axons have a protective sheath around it. It is called Myelin . It is often called as ‘the white matter’. Myelin acts as an insulator to the electric signals, which controls the flow of information only to correct places. This Myelin coat contains a variety of lipids and many other chemicals.
Myelin Disorders are classified into 2 groups:
The first group is the most common type. It is named as Multiple Sclerosis . When the myelin is taken out of the axon, the damage is repaired by another group of cells in the central nervous system. In this process scar tissues are formed which are hard plaques. These hard plaques interfere with the flow of electrical signals. Hence the coordination in the body activity is lost. Major communication related disorders include – problems in speech or swallowing.
The second group disease,is named as Hereditary Metabolic Disorders. They include the eight leukodystrophies. ‘Leuko’ means ‘white’ , referring to the myelin sheath and ‘dystrophy’ means ‘imperfect growth’ . The following diseases among the eight leukodystrophies are related to communication disabilities:
Metachromatic Leukodystrophy affects the growth and development of myelin.
The affected children begin with muscle wasting and weakness, gradual loss of vision, difficulty to swallow, paralysis and other muscle related developmental delays. Children often die by they complete 5 years of age. Few children develop this condition between 3–10 years of age begin with poor school performance and low mental ability. Death may occur within 10-15 years of age. In adults, it develops by the age of 16.
Krabbe Disease is a rare disease. It also affects the myelin sheath. Infants with this condition are normal at birth. Symptoms begin at 3-6 months of age with fevers, limb stiffness, feeding problems, vomiting, and slow coordination in brain and other organs. Main symptoms are muscle weakness, deafness, blindness, paralysis and difficulty in swallowing.
Canavan Disease is caused by gradual damage to the nerve cells inside brain. Major symptoms affecting communication are mental retardation, loss motor skills, feeding problems, poor head control, paralysis and blindness.
Refsum’s Disease occurs due to wrong formation of myelin sheaths. Symptoms of Refsum’s disease include night blindness, difficulty in hearing and eye problems.
