Also known as poliomyelitis, infantile paralysis is an acute infectious disease caused by a virus which invades the spinal cord. Children and young adults are most commonly affected with more than 90 percent of those paralyzed less than 5 years old.
The incidence of infantile paralysis has greatly decreased in the past 20 years due to the widespread, effective use of safe oral vaccine, introduced about 1952. It is now possible to prevent poliomyelitis with oral immunization of babies, but epidemics still occurs in areas where this immunization is not undertaken.
The virus which causes polio has three immunological types. Usually infection by the virus occurs through the nose and mouth. Thereafter the virus lives and multiplies in the walls of the mouth and the gut. It is excreted in the feces for up to six weeks after infection. The virus is liable to enter the grey matter of the spinal cord which contains the nerve cells, leaving paralysis. The lumbar spine is particularly affected causing paralyzed legs but any part of the cord or the brain can be damaged.
In an epidemic, infection of the virus is very common but in only a small proportion of infections (possibly less than 1 percent) is there any illness or paralysis.
At the beginning of the illness there is a slight fever and headache which disappear after a few days. In many people there are no further symptoms. However, in others, a week or so later the headache and fever recur, with a stiff sore neck and feeling of irritability. Pain in the muscles and paralysis of variable extent may occur later. The muscle of swallowing and speech but the most common muscle groups involved are those of the legs.
If there is even a suspicion of poliomyelitis, bed rest is imperative. There is no curative treatment but the fever can be reduced with aspirin and plenty of fluids. Muscle pain and spasm can be relieved with hot moist packs directly applied to the affected area.
When the respiratory muscles are paralyzed, breathing is maintained by variety of respirators which assists or takeover completely. The earliest type of machine was the ‘iron lung’ or negative pressure machine. This consisted of a box which completely incased the body and limbs with an air-tight aperture for the neck. Pulmonary ventilation was produced by rhythmical lowering of the pressure inside the box, drawing air into the patient’s lungs. It had two serious disadvantages; difficulty in nursing care and danger of accidental inhalation of food and drinks into the lungs. That is why it is advisable to consult with a spine specialist or any other medical professional that specializes in this type of paralysis.
This led to development of intermittent positive pressure respirators which inflate the lungs at a rate of 14 – 20 cycles per minute, expiration being allowed to occur passively between each phase of positive pressure. Some respirators are driven by an electric motor, others by compressed air or oxygen. More complex machine has a mechanism whereby the action is controlled by whatever spontaneous breathing is still retained (patient-cycled respirators).
The paralysis is at its worst at the end of the first week of its presence. Thereafter, it gradually improves for up to six months. Often other muscle groups take over the function of the paralyzed muscles, minimizing the overall effect of the paralysis.