Poliomyelitis

Background

• Neurotropic enterovirus
• Extremely rare in developed world, targeted for global eradication by WHO
• Still endemic in Pakistan, Afghanistan, and Nigeria
• Fecal-oral transmission, virus enters through GI tract then reproduces in GI lymphoid tissues
• If virus reaches critical concentration, can spread to motor nuclei of spinal cord, brainstem, and reticular formation → loss of infected neurons→ cycle of muscle denervation/reinnervation→ loss of muscle function

Clinical Features

Post-polio syndrome in a child demonstrating genu recurvatum (knee bends backwards) of her right leg due to muscle weakness.

• >90% of infections are asymptomatic
• Minor (abortive) polio:
  • Fever
  • Diarrhea
  • Headache
  • Sore throat
• Non-paralytic polio:
  • Fever
  • Headache
  • Meningismus
  • Muscle spasms without paralysis
• Paralytic (spinal) polio (~1-2% of polio infections)
  • Neuro symptoms may manifest after resolution of initial febrile illness
  • Maximal paralysis at around 5 days, muscle wasting after several weeks, with most patients' paralysis resolving after about 1 year
  • Flaccid muscle weakness/paralysis
  • Fasciculations
  • Absent or decreased reflexes
  • Autonomic dysfunction (e.g. sweating disturbances, urinary retention, constipation
  • Neuropathic pain, paresthesias, though usually no sensory deficits on exam
  • Bulbar dysfunction in about 20% of spinal polio (dysphagia, dysarthria, facial weakness)
  • Encephalitis: can cause reticular formation disturbances, resulting in dysrhythmias, BP lability, hypoxia, and hypercarbia
• Post-polio syndrome
  • Occurs sometime after complete resolution of initial acute symptoms
  • Can involve same muscle groups affected during patient's acute illness, as well as those not affected during initial viral infection
  • Symptoms include muscle weakness, atrophy, fasciculations, fatigue, insomnia, joint pain, bulbar dysfunction, respiratory dysfunction

Differential Diagnosis

Weakness

• Neuromuscular weakness
  • Upper motor neuron:
    • CVA
    • Hemorrhagic stroke
    • Multiple sclerosis
    • Amyotrophic Lateral Sclerosis (ALS) (upper and lower motor neuron)
  • Lower motor neuron:
    • Spinal and bulbar muscular atrophy (Kennedy's syndrome)
  • Spinal cord disease:
    • Infection (Epidural abscess)
    • Infarction/ischemia
    • Trauma (Spinal Cord Syndromes)
    • Inflammation (Transverse Myelitis)
      • Acute flaccid myelitis
    • Degenerative (Spinal muscular atrophy)
    • Tumor
  • Peripheral nerve disease:
    • Guillain-Barre syndrome
    • Toxins (Ciguatera)
    • Tick paralysis
    • Diabetic peripheral neuropathy
  • Neuromuscular junction disease:
    • Myasthenia gravis crisis
    • Botulism
    • Organophosphate toxicity
    • Lambert-Eaton myasthenic syndrome
  • Muscle disease:
    • Rhabdomyolysis
    • Dermatomyositis
    • Polymyositis
    • Alcoholic myopathy
• Non-neuromuscular weakness
  • Can't miss diagnoses:
    • ACS
    • Arrhythmia/Syncope
    • Severe infection/Sepsis
    • Hypoglycemia
    • Periodic paralysis (electrolyte disturbance, K, Mg, Ca)
      • Hypokalemic periodic paralysis
      • Thyrotoxic periodic paralysis
    • Respiratory failure
  • Emergent Diagnoses:
    • Symptomatic Anemia
    • Severe dehydration
    • Hypothyroidism
    • Polypharmacy
    • Malignancy
    • Aortic disease - occlusion, stenosis, dissection
  • Other causes of weakness and paralysis
    • Acute intermittent porphyria (ascending weakness)

Evaluation

• Evaluate for other causes of symptoms
• PCR: virus can be identified in throat washings (early), CSF (early), and stool/rectal swab (highest yield)
• CSF: Pleocytosis (PMN predominance initially, then mostly lymphocytes), usually ~normal opening pressure, protein, and glucose.

Management

• Protect airway, support respiration if bulbar or respiratory muscle weakness
• Supportive care, symptomatic treatment

Disposition

• Admit

See Also

• Weakness
• Enterovirus
• Fever in traveler