PPS is a diagnosed neurological condition which will affect up to 40% (depending on the study) of people who had “paralytic” polio. The main symptom of PPS is new muscle weakness that gradually worsens. It is often accompanied by decreased muscle endurance during activities, muscle and joint pain, muscle wasting, muscle spasms/twitching, and severe fatigue. These problems usually come on gradually, but may start suddenly following surgery, hospitalisation or being confined to bed. Even muscles that were believed to be unaffected by the previous bout with polio may be affected. The March of Dimes International Conference on Post-Polio Syndrome identified the Criteria for Post-Polio Syndrome as:
- Prior paralytic poliomyelitis with evidence of motor neuron loss, as confirmed by history of the acute paralytic illness, signs of residual weakness and atrophy of muscles on neurologic examination, and signs of denervation on electromyography (EMG).
- A period of partial or complete functional recovery after acute paralytic poliomyelitis, followed by an interval (usually 15 years or more) of stable neurologic function.
- Gradual or sudden onset of progressive and persistent new muscle weakness or abnormal muscle fatigability (decreased endurance), with or without generalized fatigue, muscle atrophy, or muscle and joint pain. (Sudden onset may follow a period of inactivity, or trauma or surgery.) Less commonly, symptoms attributed to PPS include new problems with breathing or swallowing.
- Symptoms persist for at least a year.
- Exclusion of other neurologic, medical and orthopaedic problems as causes of symptoms.