Nor are they the result of some new disease. The simplest explanation is that polio-damaged neurons are mad as hell and are not going to take it anymore. When polio struck, large numbers of neurons in the brain stem were damaged by the poliovirus. The surviving but damaged neurons are less able to manufacture acetylcholine, the chemical that neurons release to make muscles contract. This sprouting allowed many people who were totally paralyzed during the initial polio attack to actually walk out of the hospital some months later.
Muscles become weaker and hurt as they try to do more work than they are able to do.
And because weakened muscles can no longer support the joints, polio survivors' shoulders and elbows ache and their knees start to bend backward. While new muscle weakness and pain are reported by more than 75 percent of polio survivors, the most common PPS symptom is fatigue. Body fatigue is the feeling that you weigh a ton and that the longer you use your muscles, the more they lose strength. Brain fatigue is the feeling that you can't focus your attention, can't concentrate on what you're reading and can't stay awake as the day goes on. Researchers at Kessler Institute have recently found that polio survivors with brain fatigue do in fact have significantly impaired attention and are not able to release the brain-stimulating hormone ACTH in response to stress.