poliomyelitis
(pō‵lē-ō-mī‵ĕl-īt'ĭs 
)
[ polio- + myelitis ]
An acute infectious inflammation of the anterior horns of the gray matter of the spinal cord.
abortive p.Poliomyelitis in which the illness is mild with no involvement of the central nervous system.
acute anterior p.An acute infectious inflammation of the anterior horns of the gray matter of the spinal cord, a rare illness since the introduction and worldwide use of effective polio vaccines.
Only 223 cases of polio were reported worldwide in 2012. The near eradication of the disease has been the result of a massive public health effort spearheaded by Rotary International and the Gates Foundation, which have set a goal of making polio the second infectious disease eliminated by universal vaccination (the first disease being smallpox). In countries where polio vaccine has not been used extensively, epidemics are seasonal, occurring in summer and fall. Children are more susceptible than adults.
The causative agent is the poliovirus. The virus is excreted in the feces and remains viable for months outside the body. Infection is spread by direct contact with infected oropharyngeal secretions or feces, the virus probably entering the body via the mouth. It reaches the central nervous system through the blood. Three immunological types exist. The incubation period for infected people ranges from 5 to 35 days but is usually 7 to 12 days.
The onset is often abrupt although the ordinary manifestations of a severe cold or constipation may come on gradually, accompanied by slight elevation of temperature, frequently enduring for not more than 3 days. In acute polio, paralysis may or may not occur. In the majority of patients, the disease is mild, being limited to respiratory and gastrointestinal symptoms, such constituting the minor illness or the abortive type, which lasts only a few days. In major illness, muscle paralysis or weakness occurs with loss of superficial and deep reflexes. In such cases characteristic lesions are found in the gray matter of the spinal cord, medulla, motor area of cerebral cortex, and cerebellum. The extent of paralysis necessarily depends on the degree of nerve involvement: paralysis may be confined to one small group of muscles or affect one or all extremities. When the pharyngeal or respiratory muscles are involved, death is likely to occur unless mechanical ventilation is provided. Extensor muscle paralysis is typical of the disease.
The various types of meningitis, postinfection encephalomyelitis, and , rarely, conversion disorders can be confused with polio.
Active immunization with inactivated poliovirus vaccine has greatly reduced the incidence of paralytic poliomyelitis.
SEE: inactivated poliovirus vaccine .
Paralysis and muscle atrophy are common long-term complicatons of paralytic polio.
Ordinarily the outcome is good (mortality less than 10%). When paralysis develops, 50% of the patients make a full recovery, and about 25% have mild permanent paralysis.
Progressive paralysis (postpolio syndrome) may occur years after the acute attack, often first appearing decades after the initial infection.
SEE: postpoliomyelitis muscular atrophy ; postpolio syndrome.
Treatment is supportive. Mechanical ventilation is used for patients whose respiratory muscles are paralyzed. Physical therapy is used to attain maximum function and prevent deformities that are late manifestations of the disease.
Strict isolation with concurrent disinfection of throat discharge and feces is enforced to prevent transmission of poliovirus. A patent airway is maintained; the patient is observed closely for signs of respiratory distress; oxygen is administered as necessary, and intubation equipment or a tracheostomy tray should be available on a nearby crash-cart.
The patient should be kept on strict bedrest during the acute phase. Gentle passive range-of-motion exercises and application of hot moist packs at 20-min intervals (or tub baths for children) help alleviate muscle pain. Proper body alignment is maintained, and the patient turned frequently to prevent deformity and decubiti. A mild sedative or analgesic is administered to decrease pain and anxiety and to promote rest. The patient is observed for distended bladder due to transitory paralysis. Personal hygiene is provided, and oral hygiene is promoted. Stand ard precautions are employed to dispose of fecal excretions, which contain live virus. Fluids are provided orally (intravenously if necessary) to ensure adequate hydration and urinary output. Appetizing food is offered because anorexia is common. Antipyretics are administered to reduce fever. Fluid and electrolyte balance and elimination are monitored closely. A foot board or T-foot supports are used to prevent footdrop. Emotional support is provided. A personalized rehabilitation program is developed to assist the patient in regaining the fullest possible function. Cases must be reported to the local health department and CDC.
anterior p.Inflammation of the anterior horns of the spinal cord.
ascending p.Poliomyelitis in which paralysis begins in the lower extremities and progresses up the legs, thighs, and trunk, and finally involves the respiratory muscles.
bulbar p.Poliomyelitis in which the gray matter of the medulla oblongata is involved, affecting respiratory nerves and muscles supplied by the cranial nerves, resulting in paralysis and usually respiratory failure.
chronic anterior p.Progressive wasting of the muscles; myelopathic progressive muscular atrophy.
nonparalytic p.Pain and stiffness in the muscles of the axial skeleton, esp. of the neck and back; mild fever; increased proteins and leukocytes in the cerebrospinal fluid. Diagnosis depends on the isolation of the virus and serological reactions.
paralytic p.Poliomyelitis with a variable combination of signs of damage of the central nervous system. These include weakness, incoordination, muscle tenderness and spasms, flaccid paralysis, and disturbance of consciousness.
SEE: postpolio syndrome.
provocative p.During an epidemic of poliomyelitis, the onset of paralysis in the area close to the site of an invasive procedure. Thus an injection in muscle increases the risk of paralysis of the side of the body injected; and tonsillectomy and adenoidectomy increases the risk that poliomyelitis will affect the brainstem.