Post-polio Syndrome - An Overview

Introduction

Halstead coined the term post-polio syndrome in 1986. The disorder is characterized by muscular weakness, fatigue, and pain after many years of recovery from the infection. This condition presents itself 30 to 40 years after recovering from polio. Polio was once a cause of death and paralysis, but the introduction of inactivated polio vaccines has reduced morbidity and mortality rates.

What Is Post-polio Syndrome?

Post-polio syndrome is a disorder of the muscles and nerves. The conditions occur years after the recovery from polio infection. Post-polio syndrome leads to new muscle weakness, which worsens with time, pain in the joints and muscles, tiredness, and often exhaustion. Polio was once an epidemic in the 1950s. Severe cases of polio cause paralysis and breathing difficulties. Symptoms of polio include mild flu-like sickness to paralysis. Individuals who survive are at risk for post-polio syndrome. Post-polio syndrome is a non-contagious condition that can affect polio survivors, usually 15 to 40 years after recovery from polio. Only a polio survivor can develop PPS. Rarely one may develop a delayed reaction from the childhood vaccine years later on, known as post-polio vaccine syndrome. It is mostly seen in developed or developing countries.

What Is the Cause of Post-polio Syndrome?

There are several possible causes of post-polio syndrome. Then the virus enters the body and affects the nerve cells called motor neurons, which help carry electrical impulses between the muscles and the brain. Poliovirus particularly targets the motor neurons in the spinal cord. The motor neuron comprises a cell body, an axon (a major branching fiber), and dendrites (numerous small branching fibers). A poliovirus destroys many of these motor neurons as they are fewer in number. The healthy neurons grow bigger and sprout new fibers. This helps recover the muscle tissues but stresses the nerve cells to produce additional fibers. As time passes, this stress increases, leading to the gradual deterioration of the sprouted fibers and neuron itself. The second possible cause may be neuronal motor loss due to the reactivation of the latent virus. Finally, the foci of perivascular and interstitial cells cause muscle atrophy and denervation.

Another possibility is the reactivation of the polio survivor by an enterovirus. Studies have shown that post-polio syndrome is a loss of strength due to aging and weight gain. In individuals with post-polio syndrome, the condition occurs in weak muscles. Nonstructural issues, poor sleep, and polypharmacy cause different motor manifestations, such as verbal fluency deficits, apathy, and fatigue.

Are There Any Risk Factors for Post-polio Syndrome?

The risk factors for post-polio syndrome include:

• If the severity of the initial polio infection is high, then the individual is more to develop the sign and symptoms of post-polio syndrome.

• The age of onset of polio infection affects having post-polio syndrome. If the infection occurs during adulthood or adolescence, the individual is more likely to have post-polio syndrome.

• Excessive physical activity may stress out the motor neurons, which are already stressed, and individuals may have post-polio syndrome.

• If the recovery is greater, the individual may develop post-polio syndrome as greater recovery causes additional stress on the motor neuron.

What Is the Epidemiology of Post-polio Syndrome?

Frequency:

The incidence of post-polio syndrome ranges from 22 to 68 %. The prevalence of post-polio syndrome is 28.5 % in paralytic polio cases. Studies have suggested that all the individuals affected with polio have a 100 % chance of developing at least one sign of post-polio syndrome. The risk of post-polio syndrome is higher among individuals who sustained a permanent impairment.

Sex:

The post-polio syndrome has a female predilection. Studies based on surveys have shown that fatigue and pain are common among women.

Age:

People between the ages of 30 and 34 with a history of polio infection have a higher incidence of presenting with post-polio syndrome.

What Are the Symptoms of Post-polio Syndrome?

The signs and symptoms of post-polio syndrome include:

• Weakness in the muscles and joints that gets worse with time.

• Feeling easily exhausted and fatigued.

• Loss of muscle tissue (atrophy).

• Problems associated with breathing and swallowing.

• Sleep apnea and other sleep-related problems.

• Decreased tolerance to cold temperature.

• Disturbance in gait.

• Autonomic dysfunctions.

• Restless leg syndrome.

• Flat back syndrome.

Physical Examination Findings:

Individuals with progressive weakness and atrophy in muscles affected by the polio infection may be affected asymmetrically. Fasciculations in the atrophic muscles may be seen as a result of lower motor neuron injury. Studies have suggested that individuals with post-polio syndrome are usually obese, which indicates an association with body mass index.

What Are the Investigations for Post-polio Syndrome?

The diagnostic tests include:

1. Electromyography and nerve conduction studies.

2. Imaging studies (computed tomography or magnetic resonance imaging).

3. Muscle biopsy.

4. Blood tests.

What Is the Treatment of Post-polio Syndrome?

The treatment is mainly aimed at managing the signs and symptoms. For example, the treatment for post-polio syndrome involves:

• Energy Conservation: This includes limiting physical activities and taking frequent rests to reduce fatigue. Avoid strenuous exercises. The individuals may be advised to use assistive devices such as a walker, cane, wheelchair, or motor scooter, which may help conserve energy.

• Physical Therapy: This includes exercises that help strengthen the muscles without fatigue. They include less strenuous activities, like swimming or water aerobics.

• Speech Therapy: This helps in assisting individuals with swallowing difficulties. Voice-strengthening exercises may be helpful.

• Sleep Disorder Patterns: Changes in sleeping patterns may be advised, which include not sleeping on the back or assisting devices that help in the airway while sleeping. Individuals with restless leg syndrome may have better sleep after treatment.

• Medications: Muscle pain can be eased through medications such as Aspirin, Ibuprofen, and Acetaminophen.

Other medications involve anticonvulsants such as Gabapentin which relieves nerve pain. However, chronic opioid pain medications are avoided due to their severe side effects.

What Is the Differential Diagnosis of Post-polio Syndrome?

The differential diagnosis for post-polio syndrome includes:

• Chronic infection.

• Anemia.

• Depression.

• Deconditioning.

• Collagen disorders.

• Hypothyroidism.

• Infectious myopathy.

• Weight gain.

• Weakness due to aging.

• Myasthenia gravis.

Conclusion

Post-polio syndrome is a condition affecting the nerves and muscles in individuals who have recovered from a polio infection after many years. Post-polio syndrome leads to new muscle weakness, which worsens with time, pain in the joints and muscles, tiredness, and often exhaustion. Treatment mainly involves managing signs and symptoms.