Post Polio Syndrome

POST POLIO SYNDROME (PPS)

Post-polio syndrome (PPS) is a condition that affects polio survivor’s 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 and also in muscles that seemingly were unaffected by the virus.  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 are common some individuals experience only minor symptoms while others develop visible muscle weakness and atrophy.

PPS is rarely life threatening, but the symptoms can interfere significantly with the 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, which could lead to pneumonia.
The severity of weakness and disability after recovery from poliomyelitis tends to predict who might be at higher risk of developing PPS.  Individuals who had minimal symptoms from the original illness are more likely to experience only mild PPS symptoms.  People originally hit hard by the poliovirus attack and who attained a greater 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 continues to be unknown.  Studies have shown a wide difference regarding the prevalence of PPS within different areas of the same nation, or between different nations.  According to estimates by the National Center for Health Statistics, more than 440,000 polio survivors in the United States may be at risk for PPS.  Researchers estimate that the condition affects 25 to 50 percent of these survivors, or possibly as many as sixty percent, depending on how the disorder is defined and which study is quoted.
While polio is a contagious disease, PPS is not transmissible, but one must be a polio survivor to contract PPS.
The cause of PPS is unknown but experts have offered hypotheses to explain the phenomenon.  The new weakness of PPS appears to be related to the degeneration of individual nerve terminals in the motor units that remain in the spinal cord after the initial illness.  A motor unit is formed by a nerve cell (or motor neuron) and the muscle fibers it activates.  The poliovirus attacks specific neurons in the brainstem and the anterior areas of the spinal cord.  In an effort to compensate for the loss of these motor neurons, ones that survive the virus attack sprout new nerve-end terminals, connecting with the orphaned muscle fibers--which may result in recovery of movement and gradual gain in power in the affected limbs.
Years of high use of these recovered motor units adds stress to the neuronal cell body, which then may not be able to maintain the work demands and result in the slow deterioration of muscles.  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 has a slow and progressive course.
Through years of studies, scientists at the National Institute of Neurological Disorders and Stroke and at other institutions have shown that the weakness of PPS is very slowly progressing and marked by periods of relative stability followed by new declines in the ability to carry out usual daily activities.
The diagnosis of PPS relies nearly entirely on clinical information.  There are no laboratory tests specific for this condition and symptoms may vary greatly among individuals.  Physicians arrive at a diagnosis of PPS by completing a comprehensive medical history and physical examination and by excluding other disorders that could explain the symptoms.  Researchers and physicians typically use the following criteria to establish a diagnosis:

Criteria for diagnosis of post-polio syndrome

  • 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 neuromuscular examination, and signs of nerve damage on electromyography (EMG).  Rarely, persons have subclinical paralytic polio, described as a loss of motor neurons during acute polio but with no obvious deficit.  That prior polio now needs to be confirmed with an EMG.  In addition, a reported history of no paralytic polio may be inaccurate.
  • 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.
  • Gradual 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.  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 orthopedic problems as causes of symptoms.

PPS may be difficult to diagnose in some people because other medical conditions can complicate the evaluation.  Depression, for example, also is associated with fatigue and can be misinterpreted as PPS or vice versa.  For this reason, some clinicians use less restrictive diagnostic criteria, while others prefer to categorize new problems as the late effects of polio—for example, shoulder osteoarthritis from walking with crutches, a chronic rotator cuff  tear leading to pain and disuse weakness, or breathing insufficiency due to progressive scoliosis.
Polio survivors with new symptoms resembling PPS symptoms need to visit a physician trained in neuromuscular disorders to clearly establish the origin and potential causes for declining strength and to assess progression of weakness not explained by other health problems.
Physicians may use magnetic resonance imaging (MRI), computed tomography (CT), neuroimaging, and electrophysiological studies as tools to investigate the course of decline in muscle strength.  Less commonly, they will conduct a muscle biopsy or a spinal fluid analysis.  These tests are also important to exclude other, possibly treatable, conditions that mimic PPS.  It is important to remember that polio survivors may acquire other illnesses and should always have regular check-ups and preventive diagnostic tests.
Currently no effective pharmaceutical treatments 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 fatigue. 
Researchers at the National Institutes of Health (NIH) have tried treating PPS patients with high doses of steroids (prednisone) and demonstrated a mild improvement in their condition, but the results were not statistically significant.  The side effects from the treatment outweighed benefits, leading researchers to recommend that prednisone not be used to treat PPS.
In an effort to reduce fatigue, increase strength, and improve quality of life in PPS patients, scientists conducted two controlled studies using low doses of the drug pyridostigmine (Mestinon).  These studies showed that pyridostigmine is not helpful for individuals with PPS.
In another controlled study scientists concluded that the drug amantadine is not helpful in reducing fatigue.  In addition, other researchers recently evaluated the effectiveness of modifinil (Provigil) on reducing fatigue and found no benefit.
Preliminary studies indicate that intravenous immunoglobin may reduce pain, increase quality of life, and improve strength modestly.  Research into its use is ongoing.  Treatment trials with modafinil (a drug that promotes wakefulness) have been done but he results were discouraging, showing that the use of placebo was equally effective.  A small trial with lamotrigine (an anticonvulsant drug) showed modest effect but this study was limited.  
The future of PPS treatment may center on nerve growth factors.  Since PPS may result from the degeneration of nerve sprouts, growth factors can target these and help to regenerate new ones.  Unfortunately, one small study that NINDS scientists participated in showed that insulin-like growth factor (IGF-1), which can enhance the ability of motor neurons to sprout new branches and maintain existing branches, was not helpful.
Although there is no cure, there are recommended management strategies.  Seek medical advice from a physician experienced in treating neuromuscular disorders.  Do not attribute all signs and symptoms to prior polio.  Use judicious exercise, preferably under the supervision of an experienced professional.  Use recommended mobility aids, ventilator equipment, and revised activities of daily living.  Avoid activities that cause pain or fatigue that lasts more than ten minutes.  Pace daily activities.
Learning about PPS is important for polio survivors and their families.  Management of PPS can involve lifestyle changes.  Experiencing new symptoms and using assistive devices may bring back distressing memories of the original illness.
The symptoms of pain, weakness, and fatigue can result from the overuse of muscles and joints.  These same symptoms can also 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 who already have PPS.
Exercise is safe and effective when carefully prescribed and monitored by experienced health professionals.  Cardiopulmonary endurance training is usually more effective than strengthening exercises.  Exercise prescriptions should include:

  • the specific muscle groups to be included,
  • the specific muscle groups to be excluded, and
  • The type of exercise frequency and duration As a general safe rule, no muscle should be exercised to the point of causing ache, fatigue, or weakness.

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.  However, physicians recommend that polio survivors get the proper amount of sleep, maintain a well-balanced diet, avoid unhealthy habits such as smoking and overeating, and follow an exercise program as discussed above.  Proper lifestyle changes, especially with regard to eating style and body weight control, the use of assistive devices, and taking certain anti-inflammatory medications may help some of the symptoms of PPS.  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 role played by the brain, spinal cord, peripheral nerves, the neuromuscular junction (the site where a nerve cell meets the muscle cell it helps activate), and the muscles.  Another study is examining whether mental impairment is present in individuals with PPS and, if so, how it interferes with self-functioning.

Determining if there is an immunological link in PPS is also an area of intense interest.  Researchers who discovered inflammation around motor neurons or muscles are trying to find out if this is due to an immunological response.

Poliomyelitis is a viral disease that can affect nerves and can lead to partial or full paralysis.  Poliomyelitis is a disease caused by infection with the poliovirus.  The virus spreads by direct person-to-person contact, by contact with infected mucus or phlegm from the nose or mouth, or by contact with infected feces.

The virus enters through the mouth and nose, multiplies in the throat and intestinal tract, and then is absorbed and spread through the blood and lymph system.  The time from being infected with the virus to developing symptoms of disease (incubation) ranges from 5 - 35 days (average 7 - 14 days).

Risks include:

  • Lack of immunization against polio and then exposure to polio
  • Travel to an area that has experienced a polio outbreak

In areas where there is an outbreak, those most likely to get the disease include children, pregnant women, and the elderly.  The disease is more common in the summer and fall.

Between 1840 and the 1950s, polio was a worldwide epidemic.  Since the development of polio vaccines, the incidence of the disease has been greatly reduced.  Polio has been wiped out in a number of countries.  There have been very few cases of polio in the Western hemisphere since the late 1970s.  Children in the United States are now routinely vaccinated against the disease.

Outbreaks still occur in the developed world, usually in groups of people who have not been vaccinated.  Polio often occurs after someone travels to a region where the disease is common.  Thanks to a massive, global, vaccination campaign over the past 20 years, polio exists only in a few countries in Africa and Asia.

Post-polio syndrome is a complication that develops in some patients, usually 30 or more years after their initial infection.  Weakness may get worse in muscles that were previously weakened.  Weakness may also develop in muscles that previously were thought not to be affected.  Post-polio syndrome (PPS, or post-poliomyelitis syndrome or post-polio sequelae) is a condition that affects approximately 25–50% of people who have previously contracted poliomyelitis—a viral infection of the nervous system—after the initial infection.  Typically, the symptoms appear 15–30 years after recovery from the original paralytic attack, at an age of 35 to 60.  Symptoms include acute or increased muscular weakness, pain in the muscles, and fatigue.  The same symptoms may also occur years after a nonparalytic polio (NPP) infection.

The precise mechanism that causes PPS is unknown.  It shares many features with the post-viral chronic fatigue syndrome, but unlike that disorder, it tends to be progressive, and as such can cause a tangible loss of muscle strength.  Treatment is primarily limited to adequate rest, conservation of available energy, and supportive measures, such as leg braces and energy-saving devices such as powered wheelchairs, analgesia (pain relief) and sleep aids.

Signs and symptoms

After a period of prolonged stability individuals who had been infected and recovered from polio begin to experience new signs and symptoms, characterized by muscular atrophy (decreased muscle mass), weakness, pain and fatigue in limbs that were originally affected or in limbs that didn't seem to have been affected at the time of the initial polio illness.  PPS is a very slowly progressing condition marked by periods of stability followed by new declines in the ability to carry out usual daily activities.  Most patients become aware of their decreased capacity to carry out daily routines due to significant changes in mobility, decreasing upper limb function and lung capability.  Fatigue is often the most disabling symptom; even slight exertion often produces disabling fatigue, which can also intensify other symptoms.  Problems breathing or swallowing, sleep-related breathing disorders, such as sleep apnea and decreased tolerance for cold temperatures are other notable symptoms.

Increased activity during intervening healthy years between the original infection and onset of PPS can amplify the symptoms.  Thus, contracting poliomyelitis at a young age can result in particularly disabling PPS symptoms.

Numerous theories have been proposed to explain post-polio syndrome.  Despite this, there are currently no defined causes of PPS.  The most widely accepted theory of the mechanism behind the disorder is "neural fatigue”.

The neural fatigue theory proposes that the enlargement of the motor neuron fibers places added metabolic stress on the nerve cell body to nourish the additional fibers.  After years of use, this stress may be more than the neuron can handle, leading to the gradual deterioration of the sprouted fibers and, eventually, the neuron itself.

Another theory is that people who have recovered from polio lose remaining healthy neurons at a faster rate than normal.  However, little evidence exists to support this idea.  Finally, it has been proposed that the initial polio infection causes an autoimmune reaction, in which the body's immune system attacks normal cells as if they were foreign substances.  Again, compared to neural fatigue, the evidence supporting this theory is quite limited

The treatment for post-polio syndrome is generally palliative and consists of rest, analgesia (pain relief) and utilization of mechanisms to make life easier such as powered wheelchairs.  There are no reversive therapies.

PPS increases the stress on the musculoskeletal system due to increasing muscular atrophy.

Because PPS can fatigue facial muscles, as well as cause dysphagia (difficulty swallowing), dysarthria (difficulty speaking) or aphonia (inability to produce speech), persons with PPS may become malnourished due to difficulty eating. 

In general, PPS is not life threatening.  The major exception is patients left with severe residual respiratory difficulties, who may experience new severe respiratory impairment.  Studies have shown that, compared to control populations, PPS patients lack any elevation of antibodies against the poliovirus, and because no poliovirus is excreted in the feces, it is not considered a recurrence of the original polio.  Further, there is no evidence that the poliovirus can cause a persistent infection in humans.  PPS has been confused with amyotrophic lateral sclerosis (ALS), which progressively weakens muscles.  PPS patients do not have an elevated risk of ALS.

There have been no sufficient longitudinal studies on the prognosis of post-polio syndrome; however, several physicians based on experience have made speculations.  Fatigue and mobility usually return to normal over a long period.  The prognosis also differs depending upon different causes and factors affecting the individual.  An overall mortality rate of twenty-five percent exists due to possible respiratory paralysis of persons with post-polio syndrome; otherwise, post-polio syndrome is usually non-lethal.

Post-polio syndrome occurs in approximately 25–50% of people who survive a poliomyelitis infection.  On average, it occurs 30–35 years afterwards; however, delays of between 8–71 years have been recorded.  The disease occurs sooner in persons with more severe initial infection.  Other factors that increase the risk of post polio syndrome include increasing length of time since acute poliovirus infection, presence of permanent residual impairment after recovery from the acute illness, and female sex.

How Can Medical Marijuana Help PPS?

  • Cannabinoids are anti-convulsives
  • Cannabinoids are appetite stimulants
  • Cannabinoids relieve insomnia
  • Cannabinoids relieve muscle spasms
  • Cannabinoids are anti-microbial
  • Cannabinoids are immunosuppressants
  • Cannabinoids are analgesics (pain relief)
  • Cannabinoids relieve neuropathy
  • Sativas are anti-depressants

Best Strains:  Sativa hybrids,  (Sativa x Indica), (60:40)  for all other symptoms
Indica hybrids (Indica x Sativa) for pain symptoms

References



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