Polio, Emergency Medicine

Basics

Description

Caused by poliovirus infection
Incubation period 7 " “14 days
Duration <1 wk
Clinical manifestations are defined as follows:
- Subclinical (i.e., not apparent) 90 " “95%
- Abortive poliomyelitis 4 " “8%:
  - Clinically indistinct from many other viral infections (fever, myalgias, malaise)
  - Only suspected to be polio during an epidemic
- Nonparalytic poliomyelitis 1 " “2%:
  - Differs from abortive poliomyelitis by the presence of meningeal irritation
  - Course similar to any aseptic meningitis
- Paralytic poliomyelitis 0.1%, which is further subdivided:
  - Spinal paralytic poliomyelitis (frank polio)
  - Bulbar paralytic poliomyelitis (10% of paralytic polio): Paralysis of muscle groups innervated by cranial nerves; involves the circulatory and respiratory centers of the medulla with high mortality
  - Mixed bulbospinal poliomyelitis
- Postpoliomyelitis syndrome:
  - New onset of increased muscle weakness, pain, and focal or generalized atrophy
  - Occurs 8 " “70 yr after the active illness, usually in the previously affected limb
  - Risk factors include age at time of infection, extent of recovery and female sex (increased risk with better recovery)
  - Gradual progression

Etiology

Polioviruses:
- Picornaviruses
- Small, nonenveloped RNA viruses of the enterovirus genera
- 3 subtypes: 1, 2, 3
Fecal " “oral route transmission
- Enters through oral cavity
- Replicates in pharynx, GI tract, and lymphatics
Humans are the only natural host and reservoir
Poliovirus selectively destroys motor and autonomic neurons
Natural (wild) virus has been completely eliminated in US since 1979
Oral poliovirus vaccine (OPV):
- Accounts for only poliomyelitis seen in US
  - 8 " “10 cases/yr of vaccine-associated paralytic poliomyelitis (VAP): Neurovirulent conversion of vaccine virus; decreased since widespread use of inactivated poliovirus vaccine (IPV)
  - VAP occurs in poorly immunized regions by acquiring properties of wild-type virus.
  - There has been a recent increase in some third word countries

Diagnosis

Signs and Symptoms

Primarily asymptomatic
Viral symptoms: Fever, headache, malaise. Respiratory symptoms: Sore throat, fatigue GI symptoms: Nausea, vomiting
Nonparalytic aseptic meningitis: Stiff neck, and or back
Muscle pain and weakness
Progressive weakness for <1 wk:
Dysphagia and dysarthria with bulbar involvement

History

Vaccination history
History of prior polio infection
Recent exposure to individual vaccinated with OPV
Recent travel to endemic countries (Nigeria, Pakistan, India, Afghanistan)
Comorbid conditions affecting immunocompetence especially B-lymphocyte disorders (e.g., hypogammaglobulinemia and agammaglobulinemia)

Physical Exam

Fever (37 ‚ °C " “39 ‚ °C)
Headache, photophobia
Nuchal rigidity
Neurologic changes:
- Muscle soreness that becomes severe muscle spasm, progressing rapidly to spotty flaccid weakness and paralysis
- Asymmetric paralysis more prominent in the lower than the upper extremities
- Urinary retention (50% of paralytic cases)
- Reflexes initially hyperactive, then absent
- Apprehensive and irritable, occasionally drowsy
- No sensory loss associated with the motor deficit

More likely to have a biphasic acute course: ‚

Viral-type syndrome for 1 " “2 days
Symptom-free period of 2 " “5 days
Then an abrupt onset of the major illness

Essential Workup

Clinical diagnosis
Differentiate from other causes of acute paralysis.
Notify public health officials when diagnosis suspected.

Diagnosis Tests & Interpretation

Lab

CBC:
- WBC normal or mildly elevated
Diagnosis confirmed by:
- Comparing acute with convalescent sera for antigen titers
- Isolation of virus from blood, CSF, stool, throat secretions (within week 1 of infection)

Diagnostic Procedures/Surgery

Lumbar puncture/CSF analysis:
- Abnormalities typical of aseptic meningitis (increased lymphocytes and elevated protein)
- Poliovirus rarely isolated from the CSF
Electrodiagnostics:
- Normal to slow motor function
- Sensory function intact

Differential Diagnosis

Abortive poliomyelitis is similar to many viral illnesses.
Nonparalytic poliomyelitis is indistinguishable from any viral, aseptic meningitis.
Paralytic poliomyelitis:
- Amyotrophic lateral sclerosis
- Guillain " “Barre (not febrile, symmetric, not ill appearing)
- Acute transverse myelitis
- Spinal cord compression/infarction
- Multiple sclerosis
- Rhabdomyolysis
- Acute intermittent porphyria
- West Nile virus
- Diphtheria
- Botulism
- Tick paralysis
- Encephalitis

Treatment

Rare fatal cases come from respiratory insufficiency, which requires prompt ventilatory support. ‚

Initial Stabilization/Therapy

Aggressive pulmonary toilet and early intubation mandated for respiratory insufficiency ‚

Ed Treatment/Procedures

Supportive and symptomatic management
Analgesics for severe muscle pain and spasm
Bed rest to prevent augmentation or extension of paralysis
Paralytic poliomyelitis tends to localize to a limb that has been the site of intramuscular injection or injury within 2 " “4 wk prior to the onset of infection:
- Avoid any unnecessary tissue damage in suspected cases
- No antiviral agents available
- Prevention
Prevention
IPV:
- Costly
- Painful
- No conferred immunity
- No VAP, which previously accounted for all poliomyelitis cases in US
OPV:
- Accounted for only poliomyelitis seen in US (8 " “10 cases/yr)
- Incidence of VAP: 1/900,000 (immunocompromised: 1/1,000):
  - Most at risk are the underimmunized young and their caretakers.
- Confers immunity to unvaccinated contacts by fecal " “oral spread.
- Inexpensive
- No longer available in US
- Still remains the vaccine recommended by WHO Expanded Program on Immunization

Follow-Up

Disposition

Admission Criteria
All acute-phase paralytic poliomyelitis for strict bed rest and observation for respiratory symptoms: ‚

Isolate from nonvaccinated personnel.

Discharge Criteria
No evidence of nervous system involvement and no danger of contact with nonvaccinated population: ‚

Deterioration of muscle strength usually ends after 3 " “5 days

Followup Recommendations

Physical therapy: ‚

Only 1/3 of the people with acute flaccid paralysis regain full strength
Lamotrigine may decrease pain, improve symptoms and quality of life.
IV immunoglobulin (IVIg) may improve muscle strength, has not been proven to decrease pain or improve quality of life.

Pearls and Pitfalls

Most cases are asymptomatic, with symptoms ranging from viral illness to acute flaccid paralysis.
IPV is the only vaccine available in US; however OPV is still the vaccine of choice for global eradication.
Diagnosis is primarily clinical and is confirmed by virus isolation from blood, CSF, stool, or throat secretions.
Treatment is supportive; all acute-phase paralytic poliomyelitis patients should be admitted for observation with close monitoring of the respiratory system.
If the patient survives the acute stage, paralysis of respiration and deglutition usually recovers completely.
Paralytic poliomyelitis may occur decades after initial infection and manifests with neurologic and non-neurologic symptoms.

Additional Reading

Alexander ‚ L, Birkhead ‚ G, Guerra ‚ F, et al. Ensuring preparedness for potential poliomyelitis outbreaks: Recommendations for the US poliovirus vaccine stockpile from the National Vaccine Advisory Committee (NVAC) and the Advisory Committee on Immunization Practices (ACIP). Arch Pediatr Adolesc Med. 2004;158:1106 " “1112.
American Academy of Pediatrics: Report of the Committee on Infectious Diseases. 29th ed. Elk Grove, Il; 2012.
Bouza ‚ C, Mu ƒ ±oz ‚ A, Amate ‚ JM. Postpolio syndrome: A challenge to the health-care system. Health Policy. 2005;71(1):97 " “106.
Centers for Disease Control and Prevention (CDC). Imported vaccine-associated paralytic poliomyelitis " ”United States, 2005. MMWR Morb Mortal Wkly Rep. 2006;55(4):97 " “99.
Centers for Disease Control and Prevention (CDC). Updated recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding routine poliovirus vaccination. MMWR Morb Mortal Wkly Rep. 2009;58(30):829 " “830.
Centers for Disease Control and Prevention (CDC). Tracking progress toward global polio eradication " ”worldwide, 2009 " “2010. MMWR Morb Mortal Wkly Rep. 2011;60(14):441 " “445.
Howard ‚ RS. Poliomyelitis and the postpolio syndrome. BMJ. 2005;330(7503):1314 " “1318.
Ropper ‚ AH, Samuels ‚ MA. Chapter 33. Viral infections of the nervoussystem, chronic meningitis, and prion diseases. In:Ropper ‚ AH,Samuels ‚ MA, eds. Adams and Victors Principles of Neurology. 9thed. New York, NY: McGraw-Hill; 2009.
Shahzad ‚ A, K ƒ ¶hler ‚ G. Inactivated polio vaccine (IPV): A strong candidate vaccine for achieving global polio eradication program. Vaccine. 2009;27(39):5293 " “5294.

Codes

ICD9

045.00 Acute paralytic poliomyelitis specified as bulbar, poliovirus, unspecified type
045.20 Acute nonparalytic poliomyelitis, poliovirus, unspecified type
045.90 Acute poliomyelitis, unspecified, poliovirus, unspecified type
045.91 Acute poliomyelitis, unspecified, poliovirus type I
045.92 Acute poliomyelitis, unspecified, poliovirus type II
045.93 Acute poliomyelitis, unspecified, poliovirus type III
045.9 Unspecified acute poliomyelitis

ICD10

A80.30 Acute paralytic poliomyelitis, unspecified
A80.4 Acute nonparalytic poliomyelitis
A80.39 Other acute paralytic poliomyelitis
A80.9 Acute poliomyelitis, unspecified

SNOMED

240460008 Acute paralytic poliomyelitis
14535005 Acute nonparalytic poliomyelitis
240459003 Abortive poliomyelitis
398102009 Acute poliomyelitis (disorder)
446958005 acute paralytic poliomyelitis due to Human poliovirus 1 (disorder)
447262002 acute paralytic poliomyelitis due to Human poliovirus 2 (disorder)
447378002 acute paralytic poliomyelitis due to Human poliovirus 3 (disorder)

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