The symptoms are caused by the damaging effects of the viral infection on the nervous system and typically occur 15 to 30 years after an initial acute paralytic attack.
It shares many features with chronic fatigue syndrome, but unlike that disorder it tends to be progressive and can cause loss of muscle strength.
Treatment is primarily limited to adequate rest, conservation of available energy, and supportive measures, such as leg braces and energy-saving devices such as powered wheelchairs, analgesia (pain relief), and sleep aids.
After a period of prolonged stability, some people who recover from polio infections begin to experience new signs and symptoms, characterised by muscular atrophy, weakness, pain, and limb fatigue.
[2] PPS is a very slowly progressing condition marked by periods of stability followed by new declines in the ability to carry out usual daily activities.
[3] When these neurons no longer carry on sprouting, fatigue occurs due to the increasing metabolic demand of the nervous system.
[8] Another theory is that people who have recovered from polio lose remaining healthy neurons at a faster rate than normal.
[9] Finally, the initial polio infection is thought to cause an autoimmune reaction, in which the body's immune system attacks normal cells as if they were foreign substances.
[9] Diagnosis of PPS can be difficult, since the symptoms are hard to separate from complications due to the original polio infection, and from the normal infirmities of aging.
Three important criteria are recognized, including previous diagnosis of polio, long interval after recovery, and gradual onset of weakness.
Magnetic resonance imaging, neuroimaging, and electrophysiological studies, muscle biopsies, or spinal fluid analysis may also be useful in establishing a PPS diagnosis.
[11] PPS treatment concerns comfort (relieving pain via analgesics) and rest (via use of mechanisms to make life easier, such as a powered wheelchair) and is generally of palliative care.
Such can be achieved by lifestyle changes, such as additional (daytime) sleep, reducing workload, and weight loss for obesity.
Management should focus on treatments such as hydrotherapy and developing other routines that encourage strength, but do not affect fatigue levels.
[6] A recent trend toward use of intravenous immunoglobulin, which had yielded promising albeit modest results,[13] but as of 2010[update] proves insufficient to recommend as a treatment.
[15] PPS with respiratory involvement requires exceptional therapy management, such as breathing exercises and chest percussion to expel secretions (clearing of the lungs) on a periodic basis (monitored via stethoscope).
[6] No sufficient longitudinal studies have been conducted on the prognosis of PPS, but speculations have been made by several physicians based on experience.