A New Challenge for Former Polio Patients

by Food and Drug Administration (FDA)

Though Emily (not her real name) was nearly 10 when she contracted polio, she has almost no memory of her illness, nor does she want to recall it. Her mother told her, "Forget, forget" — and Emily forgot.

Glimmerings of an endless summer in the hospital and a machine that helped her to breathe sometimes surface in her dreams. Long after she was well, when she was grown up, her mother mentioned that at one point the doctors didn't know whether she would live or die.

Emily made a complete recovery from this sometimes paralyzing disease and was able to block out the memory of those days. But now, 40 years later, unwelcome reminders of her childhood illness are returning. She finds it increasingly difficult to walk, especially when she is overtired — which is often — and to breathe while sleeping.

More than half of the estimated 250,000 to 650,000 Americans who had paralytic poliomyelitis 30, 40, even 70 years ago are now reexperiencing some of their old symptoms in what is known as post-polio syndrome. They complain of increasing muscle weakness, joint and muscle pain, fatigue, breathing difficulties, loss of stamina, low back pain, and intolerance to cold. In at least 1 out of 25 survivors, the symptoms are disabling.

While some of these complaints may be due to aging and years of abnormal stress on weight-bearing joints in those who needed mechanical assistance to walk, this does not explain the progressive muscle weakness and muscle atrophy (wasting). Although researchers are still not sure what causes post-polio syndrome, most agree with Lauro Halstead, M.D., director of the National Rehabilitation Hospital's Post-polio Program in Washington, D.C. — and a polio survivor himself — who says: "The most widely held theory is that the new muscle weakness is related to overuse of polio-damaged nerve cells in the spinal cord."

Polio's Three Strains

Thanks to an effective vaccination program, polio has been nearly eradicated in the United States. However, as recently as the 1950s, epidemics terrorized the nation, especially in the summer months, leading to the closing of public pools and other places where people congregated (see accompanying article).

Polio is a highly contagious disease caused by a virus that has three distinct strains, called types I, II and III. Immunity to one type doesn't confer immunity to the other two. Type I, the strain that causes the most paralysis, is also the cause of most epidemics.

Polio epidemics in temperate climates occurred most frequently in the summer and early fall — the poliovirus flourishes in warm weather. Children were more often affected than adults, which is why the disease was once known as infantile paralysis. Persons at greater risk for serious neurological damage during epidemics due to lowered immunity included those who had recent inoculations or recent operations, especially removal of tonsils and adenoids (because the virus enters through the mouth and multiplies in the throat). Pregnancy also predisposed to paralytic polio infection.

The virus is found throughout the world, but primarily in undeveloped countries with insufficient immunization practices. It is excreted in large amounts in the feces of someone who has polio or is recovering from it, and is probably spread through hand-to-hand or hand-to-mouth contact. The poliovirus enters the mouth and multiplies in the throat and intestinal tract. Viruses may cross from the intestinal tract into the bloodstream. They are carried to the spinal cord, where they may kill or transiently injure motor nerve cells that control skeletal muscles, causing paralysis.

Sometimes only a small group of muscles is affected, sometimes the paralysis is widespread. The legs are affected more often than the arms, but polio may partially or completely paralyze a single limb, one half of the body, even all four extremities. If the virus gets into the brain stem (bulbar polio), it can paralyze muscles that control breathing, swallowing, and other bodily functions. Most fatalities occur among those with respiratory paralysis.

Post-Polio Syndrome

Only one or two out of every 100 people infected with the polio virus develops an acute paralytic illness. In many cases, the paralysis is only temporary. Up to six months to two years after the acute attack, the muscles may recover to normal strength. The nerve cells that were undamaged or partly damaged take over the function of the dead cells by sending new sprouts to muscle fibers that have been "orphaned," thereby improving muscle strength.

The theory is that after years of this extra load, cells of polio survivors tire and rebel, resulting in new weakness both in muscles formerly affected and in those that were originally unaffected. As the muscles lose nerve stimulation, they begin to atrophy. In some cases, polio survivors must begin to wear braces again, or return to wheelchairs. Those who had bulbar polio often need devices to help them breathe. These include several types of portable ventilators or, in more serious cases, the tank ventilator or "iron lung" — a large, stationary tank that encloses all but the head in a chamber that "breathes" for the patient by negative pressure.

The new symptoms are more common among post-polio survivors who had the worst cases initially — those who needed hospital care, or were older than 10, or had paralysis in all four limbs, or needed mechanical assistance to breathe. One fact that doctors are sure about is that post-polio syndrome is not a new infection, nor is it a reactivation of the old infection.

Drug Treatment

To relieve the pain of post-polio syndrome, doctors may recommend nonsteroidal anti-inflammatory medications, such as aspirin and ibuprofen (Advil, Motrin IB, Nuprin), and heat applications on the affected area. Narcotics are avoided because they depress the central nervous system and may adversely affect breathing.

A study in progress at the National Institute of Neurological Disorders and Stroke under the direction of Marinos Dalakas, M.D., chief, neuromuscular diseases unit, is evaluating the effects of prednisone (a synthetic compound that has the same actions as a substance called cortisol produced by the adrenal gland) on patients with post-polio syndrome in a double-blind study, in which neither the investigator nor the patient knows who is getting the drug and who is getting the placebo. The current study is based on data from an ongoing study conducted since 1983 that led Dr. Dalakas to hypothesize that the immune system may be involved in the syndrome.

"We have found a number of irregularities in the immune system of post-polio patients, which is why we're using prednisone in this study," says Dr. Dalakas. "We don't know if these changes are responsible for the manifestation of muscle weakness. However, the use of prednisone as an agent that can modulate [affect] the immune system, as well as act as an anti-inflammatory agent, may prove to be effective in relieving some symptoms of post-polio patients."

The immune system fights infections by attacking bacteria and viruses that invade the body, but it can also attack parts of the body itself, causing what are known as autoimmune diseases. Prednisone can suppress a component of the immune system and is often helpful in relieving muscle weakness and pain in muscular inflammatory diseases, such as polymyositis (inflamed muscles).

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.