Causes and symptoms of PPS

If you had polio or know someone who did, you may be concerned or wish to have questions answered regarding the possible development of post-polio syndrome (PPS). Studies show up to 64% of those who had polio experience problems decades later.
This webpage has been designed for those who had polio, and their families, to help relieve any general concerns that may have arisen, as well as to provide general information.


As the name suggests, post-polio syndrome (PPS) affects people who have already been affected by polio.
PPS, also referred to as “late effects of polio” or “sequelae of polio”, refers to the symptoms that occur in 50% to 70% of people who have recovered from polio after recovery and stability for a few decades (15-40 years).
PPS is defined as new weakness and / or abnormal muscle fatigue, which may be accompanied by widespread fatigue, muscle atrophy or pain in people who have recovered from paralyzing polio.



Why post-polio syndrome (PPS) occurs is not clearly established. There are many different If you had polio or know someone who did, you may be concerned or wish to have theories. However the most probable theory so far is one which explains that the motor neurons spared by polio “sprout” to resupply muscle fibres that lost their innervation during polio, like a tree (motor neuron) growing many new branches (sprouts). These motor neurons then supply more muscle fibres than normal and so have to work harder. These new sprouts (branches) fall away after a number of years due to premature aging and exhaustion of the motor neuron caused by the increased demand on it. The muscles then lose their innervation (nerve supply), resulting in weakness. This degenerative process can also produce neuromuscular junction transmission defects (difficulties in communication between nerve and muscle) which may be the cause of muscular fatigue.



As PPS has only recently become known to medical personnel as a distinct entity, many health professions are now becoming aware of the symptoms of the disease and the effect they have on patients and their families.
There are a dazzling variety of symptoms that occur in PPS. The main symptoms of PPS can be summed up under a triad – new weakness, fatigue, and new pain. PPS is defined as new weakness and/or abnormal muscle fatigue with or without generalized fatigue, muscle atrophy, or pain in those who have recovered from paralytic polio.


New weakness

New weakness occurs with or without new muscle loss in about 20-40% of polio patients. This increasing weakness may provoke joint instabilities, resulting in various deformities which may also result in greater difficulty with walking.



Fatigue is clearly the most prominent manifestation of PPS. Two types of fatigue are reported :
  • generalized fatigue
  • local muscle fatigue
Many experience a sudden onset of generalized exhaustion after brief physical activity, known as the “polio wall”. Muscle fatigue is experienced as a gradual loss of muscle strength with continued activity, which improves with rest. Fatigue-related symptoms consist of increased sleep, decreased concentration, decreased endurance, requiring a change in lifestyle. In addition, patients with respiratory problems have a variety of other symptoms, such as increased shortness of breath, sleep disturbance, confusion, inability to concentrate, etc. These symptoms may be classified as follows :
  • General : increased weakness; increased fatigue, decreased endurance for usual activities; changes in lifestyle (e.g., need for bracing or ventilator); increased instability and falling; excessive weight gain; situational anxiety and depression (as a result of decreased endurance).
  • Neuromuscular : increased pain and deformity of joints; muscle pain; muscular twitching; increased or new muscle weakness; increased fractures (as a result of weakness).
  • Respiratory : increased shortness of breath; increased respiratory infections; difficulty in speaking; sleep disturbances; confusion, especially upon waking; inability to concentrate.


New Pain

New pain is the most prominent symptom in some patients. It is felt around certain joints and muscles. This pain is usually related to physical activity. Another type of pain described is a burning sensation, deep in the muscle and bone, and not directly related to any specific activity. This pain is the hardest to deal with.


  • PPS is not necessarily permanent; another period of stability can be experienced.
  • Non-use or under-utilization of muscle may resemble the symptoms of PPS. Indeed, inactivity can cause a reduction in muscle strength, as well as loss of endurance.
  • The loss of neuro-motors resulting from normal aging can also make the situation worse.

Others frequent conditions with polio

Certain conditions such as sleep apnea, fibromyalgia, and osteoporosis likely occur more frequently in people with previous polio than in the general population. Sleep apnea (difficulty breathing during sleep) can produce significant daytime fatigue, morning headaches, nightmares, snoring, waking during sleep, impaired cognition, and irritability. Sleep apnea can be diagnosed in a sleep clinic, and is treatable. Fibromyalgia can produce chronic, generalized pain, and has been found to occur in approximately 11 % of individuals attending a post-polio clinic. This condition can be treated with certain medications, aerobic exercise, and other measures.
Osteoporosis (loss of bone mass) likely occurs more frequently in both women and men with previous polio. It increases the risk for fracture, and is now treatable with several medications. Diagnosis and treatment of these associated disorders can result in improvement of symptoms in patients.



Diagnosis of PPS requires a careful history and physical examination. Diagnostic criteria for PPS were established in 1997 by the PPS Task Force, led by Dr. Cashman.

The following factors can increase the risk for developing PPS :

  • a greater degree of paralysis at the time of the original infection
  • a greater functional recovery after acute polio
  • a longer time since acute polio
  • and (iv) a greater age at the time of presentation to a clinic
During a physical examination the strength of all the muscles is evaluated as well as the amount of movement at each joint. The determination of PPS is done via a process of elimination of other conditions that may cause similar symptoms. Currently there is no diagnostic test for PPS. However, previous motor neuron loss due to polio can be confirmed by electromyography (EMG) testing.
Excerpted from Holman, K.G., Post-Polio Syndrome : The battle with an old foe resumes. Post-Graduate Medicine 7968, p.47 (1986)