Post-Polio Syndrome
 

What is post-polio syndrome? 

Polio, or poliomyelitis, is an infectious viral disease that can strike at any 

age and affects a person’s nervous system. 

Between the late 1940s and early 1950s, polio 

crippled around 35,000 people each year in 

the United States alone, making it one of the 

most feared diseases of the twentieth century. 

The polio vaccine was first introduced in 

1955; its use since then has eradicated polio 

from the United States. The World Health 

Organization reports polio cases have 

decreased by more than 99 percent since 

1988, from an estimated 350,000 cases then, 

to 1,352 reported cases in 2010. As a result 

of the global effort to eradicate the disease, 

only three countries (Afghanistan, Nigeria, 

and Pakistan) remain polio-endemic as of 

February 2012, down from more than 125 

in 1988. 

Post-polio syndrome (PPS) is a condition 

that affects polio survivors years after 

recovery from an initial acute attack of 

the poliomyelitis virus. Most often, polio 

survivors start to experience gradual 

new weakening in muscles that were 

previously affected by the polio infection. 

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The most common symptoms include slowly 

progressive muscle weakness, fatigue (both 

generalized and muscular), and a gradual 

decrease in the size of muscles (muscle 

atrophy). Pain from joint degeneration and 

increasing skeletal deformities such as 

scoliosis (curvature of the spine) is common 

and may precede the weakness and muscle 

atrophy. Some individuals experience only 

minor symptoms while others develop 

visible muscle weakness and atrophy. 

Post-polio syndrome is rarely life-threatening, 

but the symptoms can significantly interfere 

with an individual’s ability to function 

independently. Respiratory muscle weakness, 

for instance, can result in trouble with proper 

breathing, affecting daytime functions and 

sleep. Weakness in swallowing muscles can 

result in aspiration of food and liquids into 

the lungs and lead to pneumonia. 

Who is at risk? 

While polio is a contagious disease, PPS cannot be caught from others 

having the disorder. Only a polio survivor 

can develop PPS. 

The severity of weakness and disability 

after recovery from poliomyelitis tends to 

predict the relative risk of developing PPS. 

Individuals who had minimal symptoms 

from the original illness are more likely 

to experience only mild PPS symptoms. A 

person who was more acutely affected by 

the polio virus and who attained a greater 

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recovery may experience a more severe case 

of PPS, with greater loss of muscle function 

and more severe fatigue. 

The exact incidence and prevalence of 

PPS is unknown. The U.S. National Health 

Interview Survey in 1987 contained specific 

questions for persons given the diagnosis 

of poliomyelitis with or without paralysis. 

No survey since then has addressed the 

question. Results published in 1994-1995 

estimated there were about 1 million 

polio survivors in the U.S., with 443,000 

reporting to have had paralytic polio. 

Accurate statistics do not exist today, 

as a percentage of polio survivors have 

died and new cases have been diagnosed. 

Researchers estimate that the condition 

affects 25 to 40 percent of polio survivors. 

What causes PPS? 

T he cause of PPS is unknown but experts have offered several theories to explain 

the phenomenon—ranging from the fatigue 

of overworked nerve cells to possible 

brain damage from a viral infection to 

a combination of mechanisms. The new 

weakness of PPS appears to be related to the 

degeneration of individual nerve terminals 

in the motor units. A motor unit is formed by 

a nerve cell (or motor neuron) in the spinal 

cord or brain stem and the muscle fibers it 

activates. The polio virus attacks specific 

neurons in the brain stem and spinal cord. 

In an effort to compensate for the loss of 

these motor neurons, surviving cells sprout 

new nerve-end terminals and connect with 

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other muscle fibers. These new connections 

may result in recovery of movement and 

gradual gain in power in the affected limbs. 

Years of high use of these recovered but 

overly extended motor units adds stress 

to the motor neurons, which over time 

lose the ability to maintain the increased 

work demands. This results in the slow 

deterioration of the neurons, which leads 

to loss of muscle strength. Restoration of 

nerve function may occur in some fibers a 

second time, but eventually nerve terminals 

malfunction and permanent weakness 

occurs. This hypothesis explains why PPS 

occurs after a delay and has a slow and 

progressive course. 

Through years of studies, scientists at the 

National Institute of Neurological Disorders 

and Stroke (NINDS) and at other institutions 

have shown that the weakness of PPS 

progresses very slowly. It is marked by 

periods of relative stability, interspersed 

with periods of decline. 

How is PPS diagnosed? 

T he diagnosis of PPS relies nearly entirely on clinical information. There are no 

laboratory tests specific for this condition and 

symptoms vary greatly among individuals. 

Physicians diagnose PPS after completing a 

comprehensive medical history and physical 

examination, and by excluding other 

disorders that could explain the symptoms. 

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Physicians look for the following criteria 

when diagnosing PPS: 

•	 Prior paralytic poliomyelitis with evidence 

of motor neuron loss. This is confirmed 

by history of the acute paralytic illness, 

signs of residual weakness and atrophy of 

muscles on neuromuscular examination, 

and signs of motor neuron loss on 

electromyography (EMG). Rarely, people 

had subtle paralytic polio where there 

was no obvious deficit. In such cases, 

prior polio should be confirmed with 

an EMG study rather than a reported 

history of nonparalytic polio. 

•	 A period of partial or complete functional 

recovery after acute paralytic poliomyelitis, 

followed by an interval (usually 15 years 

or more) of stable neuromuscular function. 

•	 Slowly progressive and persistent new muscle 

weakness or decreased endurance, with or 

without generalized fatigue, muscle atrophy, 

or muscle and joint pain. Onset may at 

times follow trauma, surgery, or a period 

of inactivity, and can appear to be sudden. 

Less commonly, symptoms attributed to 

PPS include new problems with breathing 

or swallowing. 

•	 Symptoms that persist for at least a year. 

•	 Exclusion of other neuromuscular, 

medical, and skeletal abnormalities as 

causes of symptoms. 

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PPS may be difficult to diagnose in some 

people because other medical conditions 

can complicate the evaluation. Depression, 

for example, is associated with fatigue and 

can be misinterpreted as PPS. A number of 

conditions may cause problems in persons 

with polio that are not due to additional 

loss of motor neuron function. For example, 

shoulder osteoarthritis from walking with 

crutches, a chronic rotator cuff tear leading 

to pain and disuse weakness, or progressive 

scoliosis causing breathing insufficiency 

can occur years after polio but are not 

indicators of PPS. 

Polio survivors with new symptoms 

resembling PPS should consider seeking 

treatment from a physician trained in 

neuromuscular disorders. It is important to 

clearly establish the origin and potential 

causes for declining strength and to assess 

progression of weakness not explained by 

other health problems. Magnetic resonance 

imaging (MRI) and computed tomography 

(CT) of the spinal cord, electrophysiological 

studies, and other tests are frequently used 

to investigate the course of decline in muscle 

strength and exclude other diseases that 

could be causing or contributing to the new 

progressive symptoms. A muscle biopsy or a 

spinal fluid analysis can be used to exclude 

other, possibly treatable, conditions that 

mimic PPS. Polio survivors may acquire other 

illnesses and should always have regular 

check-ups and preventive diagnostic tests. 

However, there is no diagnostic test for PPS, 

nor is there one that can identify which polio 

survivors are at greatest risk. 

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How is PPS treated? 

There are currently no effective pharmaceutical treatments that can stop 

deterioration or reverse the deficits caused 

by the syndrome itself. However, a number 

of controlled studies have demonstrated that 

nonfatiguing exercises may improve muscle 

strength and reduce tiredness. Most of the 

clinical trials in PPS have focused on finding 

safe therapies that could reduce symptoms 

and improve quality of life. 

Researchers at the National Institutes of 

Health (NIH) have tried treating persons 

having PPS with high doses of the steroid 

prednisone and demonstrated a mild 

improvement in their condition, but the 

results were not statistically significant. 

Also, the side effects from the treatment 

outweighed benefits, leading researchers 

to conclude that prednisone should not be 

used to treat PPS. 

Preliminary studies indicate that intravenous 

immunoglobulin may reduce pain and increase 

quality of life in post-polio survivors. 

A small trial to treat fatigue using lamotrigine 

(an anticonvulsant drug) showed modest 

effect but this study was limited and larger, 

more controlled studies with the drug were 

not conducted to validate the findings. 

Although there are no effective treatments, 

there are recommended management 

strategies. Patients should consider seeking 

medical advice from a physician experienced 

in treating neuromuscular disorders. 

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Patients should also consider judicious use 

of exercise, preferably under the supervision 

of an experienced health professional. 

Physicians often advise patients on the 

use of mobility aids, ventilation equipment, 

revising activities of daily living activities 

to avoid rapid muscle tiring and total body 

exhaustion, and avoiding activities that 

cause pain or fatigue lasting more than 

10 minutes. Most importantly, patients 

should avoid the temptation to attribute all 

signs and symptoms to prior polio, thereby 

missing out on important treatments for 

concurrent conditions. 

Learning about PPS is important for polio 

survivors and their families. Managing 

PPS can involve lifestyle changes. Support 

groups that encourage self-help, group 

participation, and positive action can be 

helpful. Counseling may be needed to help 

individuals and families adjust to the late 

effects of poliomyelitis. Experiencing new 

symptoms of weakness and using assistive 

devices may bring back distressing memories 

of the original illness. 

What is the role of exercise in the 

treatment of PPS? 

Pain, weakness, and fatigue can result from the overuse of muscles and joints. 

These same symptoms also can result from 

disuse of muscles and joints. This fact has 

caused a misunderstanding about whether 

to encourage or discourage exercise for polio 

survivors or individuals with PPS. 

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Exercise is safe and effective when carefully 

prescribed and monitored by experienced 

health professionals. Exercise is more likely 

to benefit those muscle groups that were 

least affected by polio. Cardiopulmonary 

endurance training is usually more effective 

than strengthening exercises, especially 

when activities are paced to allow for 

frequent breaks and strategies are used to 

conserve energy. Heavy or intense resistive 

exercise and weight-lifting using polioaffected muscles may be counterproductive, 

as this can further weaken rather than 

strengthen these muscles. 

Exercise prescriptions should include 

•	 the specific muscle groups to be included, 

•	 the specific muscle groups to be excluded, 

and 

•	 the type of exercise, together with 

frequency and duration. 

Exercise should be reduced or discontinued 

if it causes additional weakness, excessive 

fatigue, or unduly prolonged recovery 

time that is noted by either the individual 

with PPS or the professional monitoring the 

exercise. As a general rule, no muscle should 

be exercised to the point of causing ache, 

fatigue, or weakness. 

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Can PPS be prevented? 

Polio survivors often ask if there is a way to prevent the development of 

PPS. Presently, no intervention has been 

found to stop the deterioration of surviving 

neurons. Physicians recommend that polio 

survivors get a good night’s sleep, maintain 

a well-balanced diet, avoid unhealthy habits 

such as smoking and overeating, and follow 

a prescribed exercise program. Lifestyle 

changes, such as weight control, the use of 

assistive devices, and taking certain antiinflammatory medications, may help with 

some of the symptoms of PPS. 

What research is being done? 

Scientists are working on a variety of investigations that may one day help 

individuals with PPS. Some basic researchers 

are studying the behavior of motor neurons 

many years after a polio attack. Others are 

looking at the mechanisms of fatigue and 

are trying to discover the roles played by 

the brain, spinal cord, peripheral nerves, 

neuromuscular junction (the site where a 

nerve cell meets the muscle cell it helps 

activate), and muscles. 

Determining if there is an immunological link 

in PPS is also an area of interest. Researchers 

who discovered inflammation around motor 

neurons or muscles are trying to find out 

what causes this immunological response. 

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Where can I get more information? 

For more information on neurological disorders or research programs funded 

by the National Institute of Neurological 

Disorders and Stroke, contact the Institute’s 

Brain Resources and Information Network 

(BRAIN) at: 

BRAIN 

P.O. Box 5801 

Bethesda, MD 20824 

800-352-9424 

www.ninds.nih.gov 

Information also is available from the 

following organizations: 

Post-Polio Health International 

(Including Ventilator Users Network) 

4207 Lindell Boulevard, Suite 110 

St. Louis, MO 63108-2915 

312-534-0475 

www.post-polio.org 

www.ventusers.org 

March of Dimes 

1275 Mamaroneck Avenue 

White Plains, NY 10605 

914-997-4488 

888-MODIMES (663-4637) 

www.marchofdimes.com 

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