Post-polio syndrome (PPS) 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. Doctors estimate the incidence of PPS at about 25 percent of the survivor population. There is no definitive test for PPS; diagnosis is accomplished primarily by identifying the symptoms and excluding other possible cause. Various laboratory studies (for example, magnetic resonance imaging (MRI), neuroimaging, electrophysiological studies, and muscle biopsies or spinal fluid analysis) may aid in the diagnosis.
At present, no treatment can cure or prevent PPS. Some experimental drug treatments, including pyridostigmine and seligiline, show promise in treating symptoms of the disorder. Doctors recommend that polio survivors follow standard healthful lifestyle practices: consuming a healthful diet, exercising in moderation, and visiting a doctor regularly.
PPS is a very slowly progressing condition that is marked by long periods of stability. PPS patients, compared with control populations, do not show any elevation in antibodies against the polio virus, and since PPS affects only certain muscle groups, doctors question whether the polio virus can cause a persistent infection in humans. Except in people with severe respiratory impairment, PPS is not usually life-threatening.
Scientists are studying a number of possible treatments for post-polio syndrome, including insulin-like growth factor (IGF-1) and other growth factors. Other researchers are looking at the mechanisms behind fatigue, and trying to tease out information from the brain, muscles, and neuromuscular junction (the site at which a nerve cell meets the muscle it helps activate). Scientists are also trying to determine if there is an immunological link in this disorder.
Several theories have been proposed to explain post-polio symptoms:
Treatment for post-polio is primarily palliative, as no reliable therapy to reverse symptoms is known. Palliative treatment includes:
Causes
One significant argument in favor of the mitochondrial disruption theory is that it more adequately explains the fatigue and cognitive difficulties ("brain fog") that usually accompanies post-polio.
In final analysis, it will likely turn out that post-polio symptoms are due to some combination of mechanisms.Treatment
Though most authorities agree that rest is an important component of post-polio treatment, there is significant disagreement as to how much rest is necessary. Some hold that the best approach is to expend the absolute minimum amount of energy necessary to enjoy a reasonable lifestyle, while others feel that that there is some threshold below which energy conservation is not helpful and may in fact be harmful (due to the general effects caused by lack of exercise).
Only a few non-palliative treatments for post-polio syndrome have shown any promise, and none have been subjected to any sort of rigorous clinical testing. There are, however, a few treatments that have developed some "following" in the PPS community:
Based in part on http://www.ninds.nih.gov/health_and_medical/disorders/post_polio_short.htm