Poliomyelitis

Key Features

Essentials of Diagnosis

• Incubation period 7–14 days from exposure

• Headache, stiff neck, fever, vomiting, sore throat

• Lower motor neuron lesion (flaccid paralysis) with decreased deep tendon reflexes and muscle wasting

General Considerations

• Poliomyelitis virus, an enterovirus, is highly contagious through fecal-oral route, especially during the first week of infection

• There are three wild poliovirus serotypes, however, only wild poliovirus type 1 has remained endemic since 2012

• Pakistan and Afghanistan remain the only countries with endemic poliovirus transmission

• Acute flaccid myelitis (formerly acute flaccid paralysis)

  • Cases resembling polio with residual weakness are

    • Increasingly being reported

    • Increasingly recognized with no evidence of polio infection

• Enterovirus outbreaks are implicated but a causal association has not been established

Clinical Findings

Symptoms and Signs

• At least 95% of infections are asymptomatic

• Patients who become symptomatic can present with abortive poliomyelitis, nonparalytic poliomyelitis, or paralytic poliomyelitis

  • Abortive poliomyelitis: minor illness with nonspecific symptoms, fever, headache, vomiting, diarrhea, constipation, and sore throat lasting 2–3 days

  • Nonparalytic poliomyelitis: In addition to the above symptoms, signs of meningeal irritation and muscle spasm occur in the absence of frank paralysis

  • Paralytic poliomyelitis: present during the febrile period over 2–3 days, is a flaccid asymmetric paralysis affecting mostly the proximal muscles of the lower extremities

    • Sensory loss is very rare

    • Can be divided into two forms that may coexist: (1) spinal poliomyelitis, involving the muscles innervated by the spinal nerves; and (2) bulbar poliomyelitis, involving the muscles supplied by the cranial nerves (especially nerves IX and X) and of the respiratory and vasomotor centers

• Post-polio syndrome

  • Constellation of symptoms that affect polio survivors and is not infectious

  • The syndrome presents with signs of chronic and new denervation

  • The most frequent symptoms are progressive muscle limbs paresis with muscle atrophy, with fasciculations and fibrillation during rest activity

  • The restless leg syndrome is also reported

Differential Diagnosis

• Acute inflammatory polyneuritis (Guillain-Barré syndrome)

• Japanese encephalitis virus infection

• West Nile virus infection

• Tick paralysis

• Acute flaccid myelitis

Diagnosis

• The virus may be recovered from throat washings (early) and stools (early and late)

• PCR of washings, stool, or cerebrospinal fluid can also facilitate diagnosis

• Cerebrospinal findings

  • Normal or slightly increased pressure and protein

  • Glucose is not decreased

  • White blood cells usually < 500/mcL (0.5 × 10⁹/L) and are principally lymphocytes after the first 24 hours

  • Normal in 5% of patients

• Characteristic clinical symptoms and viral recovery from stools or neutralizing antibodies clinch the diagnosis

Treatment

• In the acute phase of paralytic poliomyelitis, patients should be hospitalized

• In cases of respiratory weakness or paralysis, intensive care is needed

• Intensive physiotherapy may ...