Dr .Ghazi F.Haji Cardiologist AL-Kindy Medical collage POLIOMYELITIS Dr .Ghazi F.Haji Cardiologist AL-Kindy Medical collage

These viruses have a propensity for the nervous system, especially the anterior horn cells of the spinal cord and cranial nerve motor neurones. The virus causes a lymphocytic meningitis and infects the grey matter of the spinal cord, brain stem and cortex. Poliomyelitis is found world-wide but its incidence has decreased dramatically following improvements in sanitation, hygiene and the widespread use of polio vaccines.

Aetiology and pathology The disease is caused by one of three polioviruses, which are a subgroup of the enteroviruses. It is much less common in developed countries following the widespread use of oral vaccines but is still a problem in the developing world. Infection usually occurs through the nasopharynx. Spread is usually via the faeco-oral route, as the virus is excreted in the faeces.

Clinical features The incubation period is 7-14 days. Figure :illustrates the various features of the infection.

Cont. Many patients recover fully after the initial phase of a few days of mild fever and headache. In others, after a week of well-being, there is recurrence of pyrexia, headache and meningism. Weakness may start later in one muscle group and can progress to widespread paresis. Respiratory failure may supervene if intercostal muscles are paralysed or the medullary motor nuclei are involved.

Investigations The CSF shows a lymphocytic pleocytosis, a rise in protein and a normal sugar content. Poliomyelitis virus may be cultured from CSF and stool.

Management In the early stages, bed rest is imperative because exercise appears to worsen the paralysis or precipitate it. At the onset of respiratory difficulties, a tracheostomy and ventilation are required. Subsequent treatment is by physiotherapy and orthopaedic measures.

Prognosis Epidemics vary widely in their incidence of non- paralytic cases and in mortality rate. Death occurs from respiratory paralysis. Muscle weakness is maximal at the end of the first week and gradual recovery may then take place for several months. Muscles showing no signs of recovery by the end of a month will probably not regain useful function. Second attacks are very rare but occasionally patients show late deterioration in muscle bulk and power many years after the initial infection.

Prevention Prevention of poliomyelitis is by immunisation with live (Sabin) vaccine. In developed countries where polio is now very rare, the live vaccine has been replaced by the killed vaccine in childhood immunisation schedules.

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