Acute Poliomyelitis Clinical Presentation

Updated: Jul 13, 2022
  • Author: Stephen Kishner, MD, MHA; Chief Editor: Stephen Kishner, MD, MHA  more...
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Most patients (95%) with poliomyelitis virus infections are asymptomatic or have only mild systemic symptoms, such as pharyngitis or gastroenteritis. These cases are referred to as minor illness or abortive poliomyelitis. The mild symptoms are related to viremia and immune response against dissemination of the virus. Only 5% of patients exhibit different severities of nervous system involvement, from nonparalytic poliomyelitis to the most severe form of paralytic poliomyelitis. [8]

  • Nonparalytic poliomyelitis or preparalytic poliomyelitis

    • The prodromal symptoms include generalized, nonthrobbing headache; fever of 38-40 º C; sore throat; anorexia; nausea; vomiting; and muscle aches. These symptoms may or may not subside in 1-2 weeks.

    • Headache and fever, as well as signs and symptoms of nervous system involvement (eg, irritability, restlessness, apprehensiveness, emotional instability, stiffness of the neck and back) and Kernig and Brudzinski signs because of meningitis, then may follow.

    • Children generally exhibit milder systemic symptoms than do adults.

    • Preparalytic symptoms also may develop into paralytic ones.

  • Paralytic poliomyelitis

    • The incubation period from virus exposure to the neurologic phase can last 4-10 days but may extend to 4-5 weeks.

    • Severe muscle pain and spasms, followed by weakness, develop. Muscle weakness tends to become maximal within 48 hours but may develop for longer than a week. No progression of weakness should be noted after the temperature drops to normal for 48 hours. Weakness is asymmetrical, with the lower limbs affected more than upper limbs.

    • Muscle tone is flaccid, and the reflexes initially are brisk but then become absent. Transient or occasionally persistent, coarse fasciculations also are observed frequently in patients with paralytic poliomyelitis.

    • Patients also complain of paresthesias in the affected limbs without real sensation loss.

    • Paralysis remains for days or weeks before slow recovery occurs over months or years. Which factors favor development of paralytic disease remains unclear, but some evidence exists that physical activity and intramuscular injections during the prodrome may be important exacerbating factors. [8]

  • Paralytic poliomyelitis with bulbar involvement

    • The purely bulbar form of poliomyelitis without limb weakness may occur in children, particularly in those whose tonsils and adenoids have been removed.

    • Bulbar paralysis with spinal involvement is more common in adults, most frequently involving the medulla and leading to dysphagia, dysphonia, respiratory failure, and vasomotor disturbance.

    • Patients may have symptoms and signs, such as hiccups, shallowness and slowing of respiration, cyanosis, restlessness, and anxiety.

    • When paralysis of diaphragmatic and intercostal musculature also occurs, patients need immediate respiratory assistance and intensive care because of life-threatening respiratory failure. Cranial nerve and bulbar involvement can cause obstruction, due to decreased respiratory drive and associated problems with mucus plugging or actual pharyngeal weakness-induced direct airway obstruction. The loss of vasomotor control with circulatory collapse also contributes to high mortality.

    • The encephalitic form of poliomyelitis

      • This form is very rare and manifests as agitation, confusion, stupor, and coma.

      • Autonomic dysfunction is common, and it has a high mortality.



Vital signs are the key to monitoring patients with poliovirus infection.

  • Muscle weakness can be assessed by muscle strength testing.

    • Usually asymmetric proximal weakness is present with more involvement of lumbar than cervical segments and more spinal cord than brainstem segments.

    • The trunk muscles are affected least.

    • Sensation should be within normal limits objectively.

    • Deep tendon reflexes are diminished or absent.

    • Atrophy of muscle may be detected 3 weeks after onset of paralysis, which becomes maximal at 12-15 weeks and remains permanent.

  • Fifty percent of adult patients with poliomyelitis experience transient acute urinary retention.

  • Stiffness and pain in the neck and back because of meningeal irritation, as well as abnormalities of autonomic function, also can be seen in some patients.

  • Cranial nerve involvement

    • Approximately 10-15% of cases affect the lower brainstem motor nuclei.

    • When the ninth and tenth cranial nerve nuclei are involved, patients develop paralysis of pharyngeal and laryngeal musculature. Unilateral or bilateral facial muscles, as well as the tongue and mastication muscles, may become paralyzed.

    • External oculomotor weakness with pupil sparing may occur in rare cases.

    • Direct infection of the brainstem reticular formation can cause breathing and swallowing disruption, as well as loss of control of the cardiovascular system.



Poliomyelitis virus infections are spread person to person, primarily through oral-fecal transmission, although it can also be transmitted via aerosol droplets. The greatest dissemination of virus occurs within families with poor sanitation and hygiene or crowded circumstances.