Five years ago, the woman took care of her house and garden. Today, at age 68, she uses a wheelchair to compensate for her muscle weakness and balance problems. She has trouble sleeping, is in constant pain and has problems concentrating, especially when she’s tired. On the days when she wakes refreshed, she feels exhausted by midmorning.

These are some of the symptoms people who had polio decades ago when they were children or young adults experience. The World Health Organization estimates that 20 million people worldwide have a polio-associated disability.¹ In the United States, an estimated 440,000 polio survivors have or are at risk of developing post-polio syndrome (PPS).^1,2

The Salk and Sabin polio vaccines, which became widely available in the U.S. in the 1950s and 1960s,³ have eradicated polio in developed countries. As a result, many healthcare providers today know little about polio infection and its consequences.

When people with PPS use the health system for treatment of common medical conditions, they are at risk for serious complications and often depend on us to advocate for their safety, independence and well-being.⁴

The term poliomyelitis is a combination of the Greek words polios, or gray, referring to the gray matter of the CNS, and myelos, referring to the myelin sheath around some nerve fibers.⁴ A virus that damages or destroys the body’s motor units in the brain and spinal cord causes acute poliomyelitis.⁴ A motor unit is a motor neuron and all the muscle fibers that it innervates.⁵ Motor neuron death deprives muscle fibers of their nerve supply, resulting in flaccid paralysis and muscle atrophy. Although flaccid paralysis results in loss of muscle tone and reflexes, muscle sensation is not affected.

The polio virus spreads person to person by contact with secretions from the nose and mouth of an infected person or by contact with infected feces.⁶ A fever and GI distress are initial symptoms. If the virus enters the vascular system and invades the CNS, the person experiences a rapid onset of muscle pain, neck stiffness, headache and increasing fever, followed by varying degrees of paralysis.^4,6

Paralytic poliomyelitis is classified as spinal, bulbar or spinobulbar. Spinal polio affects the motor neurons up and down the spinal cord. Bulbar polio affects the brain stem, including cranial nerves that control vital functions, such as breathing and swallowing.⁶ Death from bulbar polio is usually because of respiratory failure. People with spinobulbar polio have both spinal cord and cranial nerve involvement. Damage to motor neurons may affect many segmental layers of the spinal cord. If the cervical segments above C4 or C5 are affected, the diaphragm is weakened to the point that the patient will need a form of mechanical ventilation to live.⁴

In the polio epidemics of the mid-20th century, iron lungs supported respiration for those with bulbar polio and patients with weakened respiratory muscles. Enclosing nearly the entire body, an iron lung is a large negative pressure tank that first places pressure against the chest wall to expel air, then allows air to reenter the lungs.⁴

Therapy consisted of splinting and bracing to support weak or atrophied muscles, hot packs, muscle stretching and exercise.³ Surgery to improve function included muscle transfers, tendon lengthening and osteotomies, procedures to shorten, lengthen or change a bone’s alignment. Rehabilitation focused on patients’ physical effort and determination to minimize, if not overcome, disability.⁴ Most polio patients regained function.

In the late 1970s and early 1980s, people who survived the polio epidemics of the 1940s and 1950s began to report symptoms such as progressive muscle weakness, overwhelming fatigue, muscle and joint pain, cold intolerance, sleep disorders, heightened sensitivity to anesthesia and swallowing and breathing problems.⁷ Because polio was thought to be a stable condition, the symptoms were dismissed or attributed to other causes. Most people who had been affected by polio experienced a partial or full recovery, followed by an average 15-year interval of stable neurological function.⁷ In 1984, this pattern of symptoms among polio survivors was increasingly evident, and the constellation of symptoms was first referred to as PPS, a diagnosis of exclusion.⁸

Some people with PPS experience only minor symptoms while others suffer serious disability. PPS symptoms usually develop gradually, but they may be triggered by trauma, infection, surgery, an illness that results in a period of inactivity or a physically or emotionally stressful event.³ The severity of symptoms is related to how much disability the person had at the time of the acute polio infection. Those who had minor disability tend to experience mild PPS symptoms. Polio survivors who had the most residual disability and who achieved a greater functional recovery are those who may develop more disabling PPS symptoms.²

What’s the Cause?

Degenerating post-polio motor units are thought to be responsible for PPS symptoms.^5,9 In an effort to compensate for the neurons that were destroyed during the acute polio infection, the axons of some unaffected neurons grew new nerve terminals through a process called “sprouting.” New nerve terminals began to innervate muscle fibers that had been cut off, or “orphaned,” from previously healthy nerves.² This adaptation is thought to be responsible for much of the recovery that polio survivors experienced. It’s thought that these motor neurons, some of which have often grown to eight times normal size to respond to metabolic demands, can no longer carry such a heavy load.⁵ The result is the progressive muscle weakness characteristic of PPS.² Motor unit degeneration can also cause changes at the neuromuscular junction, producing the pervasive fatigue associated with PPS.⁵ Although motor neuron loss begins to occur naturally and gradually in older people, this process is accelerated in people with PPS.

Because people with PPS often experience multisystem effects, an interdisciplinary team approach is optimal.^5,10 Team members may include a primary care physician, physiatrist, neurologist, physical therapist, occupational therapist, speech pathologist, psychiatrist or psychologist, pulmonologist, orthopedist, rheumatologist, dietitian, nurse, orthotist and respiratory therapist.⁵ Most people with PPS report pain, weakness and fatigue, memory problems, breathing and swallowing problems, sleep disturbances, cold intolerance, urinary problems and emotional stress.

In about 25% of people with PPS, the associated pain is severe enough to interfere with activities of daily living.¹¹ Pain often occurs in the neck, back and extremities. Joint pain may be caused by chronic overuse of muscles that appeared to be undamaged by the initial polio infection. For example, the right leg of a person with weakened muscles in the left leg may develop pain in later life because of overuse and overcompensation. Hot or cold packs, biofeedback and massage can help minimize pain.⁸ Nonsteroidal anti-inflammatory drugs can also help relieve muscle and joint pain.

Fatigue is the most common PPS symptom; up to 91% of people with PPS report new or increased fatigue.¹¹ People with post-polio fatigue describe physical exhaustion characterized by muscle weakness and decreased endurance and a central fatigue associated with cognitive problems. For instance, people with PPS may report memory problems, such as difficulty with word finding, especially when they are fatigued or stressed. Deconditioning also exacerbates fatigue. Many polio survivors are significantly deconditioned and may take much longer than expected to recover from illness, injury or trauma.¹²

Strategies to reduce PPS fatigue and weakness include exercising carefully under supervision, avoiding muscle overuse, losing weight, bracing weakened muscles and using assistive mobility devices, such as a wheelchair or motorized scooter.^5,9 A tool such as the Borg Rating of Perceived Exertion scale can help patients assess their perception of fatigue and limit activities that cause excessive fatigue.⁵

Energy conservation is an important part of managing PPS fatigue. People with PPS need to pace physical activities, schedule frequent rest periods and eliminate unnecessary energy-consuming tasks.¹¹ Pain, weakness and fatigue can occur from overusing muscles and joints, but they can also be the result of muscle and joint disuse.² This has caused some confusion about whether to encourage or discourage exercise for polio survivors, including those with PPS symptoms.² Polio experts emphasize that physical exercise is safe and effective when it is prescribed and monitored by health professionals.² Muscle stretching and joint range-of-motion exercises are important to counteract muscle weakness and reduce muscle tightness that can interfere with function.¹² When patients with PPS have breathing capacity limitations, they need to keep their chest and abdominal muscles from tightening.¹²

Exercise can also promote continued mobility in a person with hip and thigh muscle weakness.¹² Swimming is an excellent exercise for people with PPS because the buoyancy of the water helps prevent joint and tendon stress while the aerobic effects increase endurance.¹² Intense resistive exercises or using polio-affected muscles to lift weights can further weaken rather than strengthen muscles.² Exercise should be reduced or discontinued if the person experiences increased weakness, excessive fatigue or prolonged exercise recovery time. We must encourage people with PPS to listen to their bodies and avoid activities that cause pain or exhaustion, teaching them not to overuse their muscles but to continue physical activities that do not worsen symptoms.¹

Physical therapists can prescribe exercises that strengthen muscles and improve endurance without causing fatigue, and occupational therapists can help patients modify their home environment to conserve energy. The most effective exercise regimen can help maintain muscle strength in previously affected muscles while helping to protect muscles that may not have been recognized as having been affected by polio.¹² Physical exercise can also help prevent fatigue and weight gain, which exacerbates the sedentary lifestyle associated with cardiovascular disease and osteoporosis.⁶

Respiratory problems — such as dyspnea, hypercapnia and hypoventilation — and impaired swallowing are common with PPS. Early signs of respiratory impairment include anxiety, breathlessness, fatigue, frequent respiratory infections, morning headaches and restless sleep.8 People with PPS are at increased risk of respiratory problems, such as atelectasis and pneumonia, because their weakened respiratory muscles prevent them from taking a deep breath or coughing effectively.¹²

Interventions for respiratory impairment include appropriate positioning, increased fluid intake, incentive spirometry and other forms of noninvasive positive-pressure ventilation.⁸ People with PPS need to pay attention to respiratory infections, which can worsen breathing problems. They should consider the first symptoms of the common cold, even a weak cough, as serious and potentially life-threatening.¹² To lessen the chance of respiratory infections, we should encourage people with PPS to avoid smoking, receive the pneumonia vaccine and have annual flu shots.¹¹ Obesity, spinal curvature, prolonged immobility, anesthesia and medications that compromise respiratory function can also lead to acute respiratory failure.

Use oxygen with caution in PPS patients. If a person with PPS has long-term respiratory impairment with higher-than-normal carbon dioxide blood levels, the stimulus for breathing is controlled by a low oxygen level. Increasing oxygen levels in a person whose respiratory function depends on hypoxia may cause respiratory failure.⁶ In situations in which oxygen is a primary therapy, such as an acute MI, the person’s respiratory status must be carefully evaluated.¹²

Sleep apnea is common with PPS. Because sleep apnea can eventually produce cardiopulmonary failure, prompt diagnosis and treatment is important.¹¹ Interventions range from avoiding a supine position to using continuous positive-pressure airway devices to help keep blocked airways open during sleep. Sleep disturbances may be caused by brain dysfunction or weakened upper airway muscles.

Weakness in muscles used for chewing and swallowing can cause dysphagia, especially in polio survivors who had bulbar involvement. Swallowing problems can lead to malnutrition and dehydration and increase aspiration risk.^10,13 Signs of swallowing problems include coughing, choking and frequent throat clearing.⁸ Speech therapists can teach patients ways to compensate for swallowing problems, such as using pureed foods and thickened liquids, postponing eating when fatigued and using specific swallowing techniques, such as swallowing twice for each mouthful and turning the head to one side while swallowing.^8,12

On the Alert

We must be keenly aware of the special needs of people with PPS and the risks they face when being treated for a variety of health conditions. When hospitalized, people with PPS may experience unusually severe pain, cold intolerance, self-care deficits and impaired physical mobility; they are also at risk of developing respiratory insufficiency and impaired swallowing.⁴

PPS patients are at special risk during surgery. Although anesthesia is safe, many polio survivors are reluctant to have surgery because of reports of problems associated with anesthesia.¹² Because the initial polio infection might have affected the reticular-activating system (the part of the brain responsible for alertness), people with PPS are anesthetized easily and take much longer than usual to awaken.⁸ Teach patients to inform their medical and dental healthcare providers in any situation in which anesthesia may be needed.⁶ Other potential complications associated with surgery include the possibility of needing mechanical ventilation and increased postoperative pain compared to people without PPS.¹²

Preoperative pulmonary function testing may be needed to assess whether postoperative mechanical ventilation will be needed. The need for mechanical ventilation is increased in those who use some form of ventilation assistance or those who previously used an iron lung.¹² Postoperative mechanical ventilation allows the lungs to recover from the effects of surgery; however, it may prompt a psychological reaction from people who have traumatic memories of iron lungs or other types of breathing assistance.

In the case of cold intolerance, patients may need heated blankets in the postop recovery unit.¹² People with PPS are also at increased risk for vomiting and aspiration after anesthesia.⁸ Polio experts advise those with significant symptoms to avoid same-day surgery since they require careful and sometimes extended monitoring to ensure that they can safely return home.⁶ Those with less severe symptoms may consider same-day surgery if the surgeon and anesthesiologist are experienced in treating polio survivors and if the person has adequate home assistance.¹²

As a result of damage to neurons in the brain and spinal cord, people with PPS experience a heightened pain response. Injecting local anesthetic at the surgical site, giving pain medication before the person begins to recover from anesthesia and providing patient-controlled analgesia using a continuous infusion of analgesia can help reduce pain.¹²

Polio causes a variety of nerve cell changes that worsen with age. People with PPS are very sensitive to sedating medications and muscle relaxants. Muscle relaxants are particularly dangerous for people with PPS who already have weakened respiratory musculature; polio survivors are more sensitive to muscle-relaxing agents because they have fewer neurons to block.¹² Recommendations are to start with one-half of the usual dose of these medications and to increase the dose if indicated.¹³

Any medication that produces a sedating effect should be given with caution. Common medications such as antihistamines, benzodiazepines and some antidepressants can cause profound sedation in a person with PPS.⁸ Some antibiotics and certain antineoplastic medications can increase nerve damage to already compromised cells.⁸ Common prescription medications such as beta blockers, calcium channel blockers, procainamide, quinidine, quinine and statins can increase fatigue and weakness.^6,8

Emotional Stress

Experiencing additional losses after a lifetime of adaptation can create profound emotional stress. Children with polio were removed from their families and cared for in large health centers. Many survived the helpless feeling of being in an iron lung, unable to move or breathe and dependent on others to meet their basic needs. During the acute infection, patients experienced severe muscle pain followed by months of painful therapy. Many patients had several painful surgical procedures to restore function. Coping with a second disability is a formidable task, particularly for people who were taught as youngsters that the key to recovery was to push themselves as hard as they could.

Polio survivors had varying experiences during the acute polio infection. Some recovered quickly while others were hospitalized and isolated, and went through years of rehabilitation.^1,4 Those who were very young when they had polio may not remember much. Others may have vivid memories of pain and paralysis from the infection and treatments.

Not a Return of Polio

People with PPS may worry that they are having a reactivation of the polio virus and may infect others. But people with PPS symptoms have not been reinfected nor are they contagious.² Post-Polio Health International, a group devoted to education, research and advocacy for polio survivors, advises people with PPS symptoms to seek medical advice from a physician who specializes in neuromuscular disorders and recommends that all polio survivors have yearly health exams.¹ However, some polio survivors don’t seek medical attention either because they fear reactivating memories of polio or they perceive that health providers don’t understand the late effects of polio.¹ They may also be weary of physical barriers, such as inaccessible medical offices. One study found a low level of function combined with a high incidence of comorbidity in polio survivors. One of the top barriers to health was lack of supportive health providers.^{14 (Level B)}

No intervention has been found to prevent motor neurons from continuing to deteriorate, but research continues.² Some researchers are studying mechanisms of fatigue and the role played by the brain, spinal cord, peripheral nerves and neuromuscular junction, where a nerve cell comes in contact with the muscle it activates.²

We can encourage polio survivors to contact support groups such as Post-Polio Health International and the March of Dimes Birth Defects Foundation. Some may need individual counseling to cope with the losses PPS brings. We can advocate for those with PPS in healthcare settings and educate them about situations that may worsen their condition. Knowing more about PPS can help us work in partnership with this unique and increasingly vulnerable population.

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