acute anterior poliomyelitis


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a·cute an·te·ri·or po·li·o·my·e·li·tis

a disease that results in death or irreversible damage of motor cells in the cerebrum, brainstem, and spinal cord, caused by infection with small RNA enteroviruses of the Picornaviridae group; formerly due almost solely to one of three types of polio virus, but now more often caused by coxsackieviruses types A and B, or echoviruses.

acute anterior poliomyelitis

a·cute an·te·ri·or po·li·o·my·e·li·tis

(ă-kyūt' an-tēr'ē-ŏr pō'lē-ō-mī-ĕ-lī'tis)
Inflammation of the anterior cornua of the spinal cord; an acute infectious disease caused by the poliomyelitis virus and marked by fever, pains, and gastroenteric disturbances, followed by a flaccid paralysis of one or more muscular groups, and later by atrophy.

acute anterior poliomyelitis

An acute infectious inflammation of the anterior horns of the gray matter of the spinal cord, a rare illness in the U.S. since the introduction of effective polio vaccines. In this disease, 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 the 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.

Etiology

The causative agent is the poliovirus. The virus is excreted in the feces and remains viable for months outside the body. Three immunological types exist. The incubation period for infected people ranges from 5 to 35 days but is usually 7 to 12 days.

Symptoms

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. At the end of this period, paralysis may or may not develop. 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.

Differential Diagnosis

The various types of meningitis, postinfection encephalomyelitis, and, rarely, conversion disorders can be confused with polio.

Prophylaxis

Active immunization with inactivated poliovirus vaccine has greatly reduced the incidence of paralytic poliomyelitis. See: inactivated poliovirus vaccine

Complications

Paralysis and muscle atrophy are common long-term complicatons of paralytic polio.

Prognosis

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

Incidence

Poliomyelitis is endemic throughout the world but occurs in epidemics in poorer countries. Thanks to a worldwide effort to eradicate polio through mass vaccination, reported cases have declined from 350,000 annually about 25 years ago, to slightly more than 1000 cases in 2007. Polio no longer occurs in epidemics in the U.S. (virtually all cases for the last several years have been vaccine-associated). In countries where polio vaccine has not been used extensively, epidemics are seasonal, occurring in summer and fall. Children are more susceptible than adults. 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.

Treatment

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.

Patient care

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. Standard 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.

See also: poliomyelitis
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