Acute poliomyelitis(polio) is a highly contagious viral disease which ranges in severity from in-apparent infection to overwhelming paralytic illness and death. The illness may take a number of forms. An in-apparent infection consists of an invasion by poliovirus that produces an antibody response but no systemic symptoms. An abortive infection produces transient nonspecific symptoms of a minor illness without central nervous system involvement with a rise in antibody. In nonparalytic poliomyelitis.
The major illness develops with signs and symptoms of central nervous system invasion and meningitis but no paralysis. Paralytic poliomyelitis consists of the major illness, often with a biphasic pattern, associated with flaccid weakness in one or more muscle groups, the result of the attack by the virus on the somatic motor and autonomic neurons of the spinal cord and lower brain-stem.
Differential Diagnosis of Poliomyelitis
Poliomyelitis is singular in producing an acute febrile illness with headache, stiff neck, and asymmetric, flaccid, multifocal, and progressive muscle paralysis. However, unless poliomyelitis invades the nervous system, it cannot be differentiated clinically from many other viral diseases producing myalgia or influenza-like symptoms. Similarly, aseptic meningitis can be caused by mumps, coxsackieviruses and echoviruses that can be identified only by tissue culture or serologic studies . Bacterial or fungal men- ingitides can usually be separated from nonparalytic poliomyelitis by their characteristic cerebrospinal fluid alterations, including the reduction of sugar.
Acute porphyria is characterized by a symmetric motor polyneuropathy and sometimes has an abrupt onset with diffuse peripheral pain. However, lever is usually lack- ing and there is no CSF pleocytosis. Patients with porphyria often have a history of recurrent attacks, abdominal pain, and prominent psychiatric disturbances. Appropriate urine studies will usually demonstrate por phobilinogen.
Hysteria will occasionally present a difficult clinical picture. This may be particularly the case when the sub. ject has had direct contact with paralytic poliomyelitis or during an epidemic. The hysteric has a normal cerebro- spinal fluid and rarely looks severely ill. Hysterical paralyses commonly involve an entire body part rather than selective muscles, and reflex loss is rarely commensurate with weakness. Autonomic changes are seldom prominent in hysteria. Finally, in the face of’ paralysis persisting for more than three to four weeks, electromyo graphic studies in the hysteric will rail to detect the expected presence of motor unit degeneration.
There is no specific treatment for the po- liomyelitis viral infection. Patients with known or suspected acute anterior poliomyelitis are best kept at bed rest and should be hospitalized if signs or nervous system involvement are detected. Since there is no prognostic value in knowing the exact extent of the weakness until progression has ceased, serial studies of muscle function can be restricted to pertinent examinations of bulbar function, respiration, and circulation. Patients with par- alytic and nonparalytie poliomyelitis are most comfort- able if placed on a firm bed with the back and head sup- ported. A low head pillow helps relieve neck pain, and a thin pad placed beneath the small of’ he back minimizes lumbar discomlört.
Footboards to support the weight of bedclothes help to prevent foot drop. During the acute illness, aspirin and other nonnarcotic analgesics should be used for pain relief. Narcotics and sedatives, with the exception of small and occasional doses of codeine, are dangerous and should be avoided. Hot packs provide comfort to painful muscles and should be gently laid on with minimal manipulations. More vigorous physical therapy should be deferred to the convalescent phase, although the joints should be moved passively through their full range of motion in an effort to prevent contractures.
Patients should be on liquid or minimal diets until their appetite returns. If necessary, parenteral fluids to. taling 2000 to 2500 ml should be given in order to main- tain a high fluid intake and counteract the risks of immobilization. Either indwelling or intermittent catheterization can be employed to deal with urinary re. tention, parasympathomimetic drugs not being of much help at this stage.
Prevention of Poliomyelitis
Natural infection from any of the three types of poliovirus induces lifelong immunity to the spe- cific infecting strain. Proper vaccination with either the killed- or the live-virus vaccine appears to achieve a sim- ilar result and has largely eliminated epidemic polio- myelitis from the developed countries of the world. Widespread use of poliovirus vaccines since 1955 has resulted in the virtual elimination of paralytic poliomye- litis from the United States. Paralytic poliomyelitis declined from 18,308 cases in 1954 to 17 cases in 1971 and 29 cases in 1972. A national survey in 1971 showed that 77 per cent or individuals 1 to 19 years old had received at least three doses of oral or inactivated polio- virus vaccine. Nevertheless, low immunization rates still prevail in certain disadvantaged population groups, and these represent the principal populations at future risk of paralytic disease.
Both live attenuated virus vaccines which are taken orally and inactivated virus vaccines which must be injected parenterally are effective in creating immunity against poliomyelitis. Because it is easier to administer and supervise, trivalent oral poliomyelitis vaccine has almost completely replaced both the inactivated and monovalent vaccines in this country. Oral poliomyelitis vaccine produces an immune response like that induced by natural poliovirus infection, and a primary series of three adequately spaced doses will produce immunity against the three poliovirus types in well over 90 per cent of recipients. Very rarely, paralysis has occurred in recipients of oral polio vaccine or in their close contacts within two months of administration. The estimated frequency of this complication is 1 case per 5 million doses distributed.