Physical therapy intervention in post polio
WHAT IS POLIO ?
Poliomyelitis, often called polio or infantile paralysis, is an infectious disease caused by the poliovirus. In about 0.5 percent of cases there is muscle weakness resulting in an inability to move. This can occur over a few hours to a few days. The weakness most often involves the legs but may less commonly involve the muscles of the head, neck and diaphragm. Many but not all people fully recover In those with muscle weakness about 2 to 5 percent of children and 15 to 30 percent of adults die. Another 25 percent of people have minor symptoms such as fever and a sore throat and up to 5 percent have headache, neck stiffness and pains in the arms and legs. These people are usually back to normal within one or two weeks. In up to 70 percent of infections there are no symptoms.
POST POLIO SYNDROME: Post-polio syndrome (PPS) is a condition that affects polio survivors years after recovery from an initial acute attack of the poliomyelitis virus. Post-polio syndrome is mainly characterized by new weakening in muscles that were previously affected by the polio infection and in muscles that seemingly were unaffected.
SIGN AND SYMPTOMS
Symptoms include slowly progressive muscle weakness, unaccustomed fatigue (both generalized and muscular), and, at times, muscle atrophy. Pain from joint degeneration and increasing skeletal deformities such as scoliosis are common. Some patients experience only minor symptoms. While less common, others may develop visible muscle atrophy, or wasting.
Post-polio syndrome is rarely life-threatening. However, untreated respiratory muscle weakness can result in underventilation, and weakness in swallowing muscles can result in aspiration pneumonia.
CAUSE N OCCURRENCE The cause is unknown. However, the new weakness of post-polio syndrome appears to be related to the degeneration of individual nerve terminals in the motor units that remain after the initial illness. A motor unit is a nerve cell (or neuron) and the muscle fibers it activates. The poliovirus attacks specific neurons in the brainstem and the anterior horn cells of the spinal cord. In an effort to compensate for the loss of these neurons, ones that survive sprout new nerve terminals to the orphaned muscle fibers. The result is some recovery of movement and enlarged motor units.
Years of high use of these enlarged motor units adds stress to the neuronal cell body, which then may not be able to maintain the metabolic demands of all the new sprouts, resulting in the slow deterioration of motor units. Restoration of nerve function may occur in some fibers a second time, but eventually nerve terminals malfunction and permanent weakness occurs. This hypothesis is consistent with post-polio syndrome's slow, stepwise, unpredictable course.
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 post-polio syndrome. Researchers are unable to establish a firm prevalence rate, but they estimate that the condition affects 25 percent to 50 percent of these survivors, or possibly as many as 60 percent, depending on how the disorder is defined and which study is quoted.
Criteria for diagnosis of post-polio syndrome*
1-Prior paralytic poliomyelitis with evidence ofmotor 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. Also, a reported history of nonparalytic polio may be inaccurate.
2-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.
3-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 post-polio syndrome include new problems with breathing or swallowing.
PHYSICAL THERAPY INTERVENTION
Physiotherapy is safe and effective when carefully prescribed and monitored by experienced health professionals. Cardiopulmonary endurance training is usually more effective than strengthening exercises. Heavy or intense resistive exercise and weight-lifting using polio-affected muscles may be counterproductive because they can further weaken rather than strengthen these muscles. Exercise prescriptions should include
1-the specific muscle groups to be included, 2-the specific muscle groups to be excluded, and 3-the type of exercise, together with frequency and duration. 4-Exercise should be reduced or discontinued if additional weakness, excessive fatigue, or unduly prolonged recovery time is noted by either the individual with post-polio syndrome or the professional monitoring the exercise
PLAN FOR REHABLITATION: Strengthening programs performed as described show a 60% increase on isokinetic strength, improved cardiorespiratory status, no decline in strength in 6-12 months, and 5% increase in isometric strength.
In one randomized controlled study, progressive resistance training program consisted of 3 sets of 8 isometric contractions, 3 times weekly for 12 weeks. Postpolio patients showed a significant improvement in their strength.  The training did not adversely affect motor unit survival, and the improvement was largely attributable to an increase in voluntary motor drive.
USE OF MODALITIES: Electrical stimulation has been used to strengthen weakened muscles or to reeducate muscles weakened through disuse, as well as to decrease pai
For myofascial pain, consider heat, electrical stimulation, trigger point injections, stretching exercises, biofeedback, muscle relaxation exercises, or static magnetic fields for trigger points. Exercise therapy and training programs in PPS patients should be carefully customized and planned by physiotherapists to avoid both overuse and disuse, and the level of physical activity should be modified to decrease pain.
PREVENTION: Polio survivors often ask if there is a way to prevent post-polio syndrome. Presently, no intervention has been found to stop the deterioration of surviving neurons. But physicians recommend that polio survivors get the proper amount of sleep, maintain a well-balanced diet, avoid unhealthy habits such assmoking and overeating, and follow an exercise program as discussed above. Proper lifestyle changes, the use of assistive devices, and taking certain anti-inflammatory medications may help some of the symptoms of post-polio syndrome.