Conduction velocity of peripheral nerves and electromyography in infants and children.

The methods used to measure the conduction velocity of peripheral motor nerves in arms and legs and of the distal part of sensory fibres in the hand are demonstrated. Normal values in infancy, childhood and adolescence are given and discussed in relation to the maturation of the peripheral nervous system. This maturation is further elucidated by a study of the conduction velocity of peripheral motor nerves in different groups of mentally retarded children. The normal values in different ages also serve as a reference with which to compare a value found in a child with a possibly impaired function of the peripheral nerves. Conduction velocity of peripheral nerves is normal in diseases affecting the anterior horn cells or the muscles. It is abnormally low in diseases primarily localized in the peripheral nerves. It is thus a diagnostic tool in establishing a diagnosis of polyneuropathy, a condition, which may be particularly hard to diagnose clinically in children because of the difficulties in performing a good sensory examination in young child. The clinical conditions, in which measuring of conduction velocity of peripheral nerves may be of great help, are discussed. The technique of performing electromyography is briefly reviewed. The findings in normal children of different ages are discussed in relation to the maturation of the neuromuscular system. Abnormalities typical of different diseases of the peripheral neurones and the muscles are described. Finally, the clinical conditions are discussed in which electromyography may be of diagnostic help.