What is post-polio syndrome (PPS)?Post-polio syndrome (PPS) is a condition that strikes survivors of the disease polio. PPS occurs about 20-30 years after the original bout with polio, and causes slow but progressive weakening of muscles. Post-polio syndrome (PPS) (also properly but not commonly called post-polio sequelae) is a condition that can strike polio survivors anywhere from 10 to 40 years after their recovery from polio. PPS is believed to be caused by the death of individual nerve terminals in the motor
units that remain after the initial polio attack. Symptoms include fatigue, slowly progressive muscle weakness, muscle and joint pain, and muscular atrophy. The severity of PPS depends only weakly upon how seriously the survivors were affected by the first polio attack.
Polio is a disease caused by the poliovirus. It most commonly infects younger children, although it can also infect older children and adults. About 90% of people infected by poliovirus develop only a mild case or no illness at all. However, infected people can continue to spread the virus to others. In its most severe form polio causes paralysis of the muscles of the legs, arms, and respiratory system.
About 1% of all people infected with poliovirus develop the actual disease known as polio. In these cases, the virus (which enters the person's body through the mouth) multiplies rapidly within the intestine. The viruses then invade the nearby lymphatic system. Eventually, poliovirus enters the bloodstream, which allows it to gain access to the central nervous system or CNS (the brain and spinal cord). The virus may actually infect a nerve elsewhere in the body, and then spread along that nerve to enter the brain.
The major illness associated with poliovirus often follows a mild illness, which has symptoms of fever, nausea, and vomiting. However, after a symptom-free interval of several days, the patient who is on the way to a major illness develops new symptoms such as headache and back and neck pain. These symptoms are due to invasion of the nervous system. The motor nerves (those nerves responsible for movement of the muscles) become inflamed, injured, and destroyed. The muscles, therefore, no longer receive any messages from the brain or spinal cord. The muscles become weak, floppy, and then totally paralyzed (unable to move). All muscle tone is lost in the affected limb, and the muscle begins to decrease in size (atrophy). The affected muscles are often only on one side (asymmetric paralysis) of the body. Sensation (the person's ability to feel) is not affected in these paralyzed limbs.
The maximum state of paralysis is usually reached within just a few days. The remaining, unaffected nerves then begin the process of attempting to grow branches to compensate (make up for) the destroyed nerves. This process continues for about six months. Whatever function has not been regained in this amount of time will usually be permanently lost.
Post polio syndrome (PPS) affects people who have had the poliomyelitis virus, or polio, anywhere from 10 to 40 years before. Of the 300,000 polio survivors in the US, one-quarter to one-half will have symptoms of PPS. If the initial bout with polio was severe, there is a greater chance of developing post polio syndrome. There is also a greater chance of developing more severe PPS symptoms.