Neurology · MU Sofia

46. Poliomyelitis and other polioencephalomyelitis

Covers poliomyelitis and the wider polioencephalomyelitis, from the enterovirus cause and faecal–oral spread through to the pathway from gut entry to flaccid paralysis. It separates the abortive, non-paralytic and paralytic clinical forms, then describes lower motor neuron paralysis with normal sensation, bulbar involvement and CSF findings. It closes with a differential diagnosis against Guillain-Barré syndrome, transverse myelitis, stroke and myasthenia gravis, and vaccine prevention.

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Topic 46 of 88 in the MU Sofia syllabus for Neurology (Medicine, Year 4). The free AceMed note covers it in 1 section, about 241 words (2 min of reading), with 16 flashcards.

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  1. Poliomyelitis and other polioencephalomyelitis

Poliomyelitis and other polioencephalomyelitis

Definition

Poliomyelitis: An acute viral infection caused by poliovirus affecting mainly the anterior horn cells of the spinal cord, leading to lower motor neuron paralysis.

Polioencephalomyelitis

  • More extensive infection involving: Brain (encephalon). Brainstem. Spinal cord (anterior horn cells)

Etiology:

  • Poliovirus (Enterovirus genus)
  • Transmission: fecal–oral route
  • Humans are the only reservoir

Pathogenesis

Entry via gastrointestinal tract→ Viremia → CNS invasion (anterior horn cells) → Destruction of motor neurons → flaccid paralysis

Clinical Forms

A. Abortive (minor illness): Fever. Malaise. Headache. No CNS involvement

B. Non-paralytic poliomyelitis: Meningeal irritation. Neck stiffness. CSF changes (aseptic meningitis pattern)

C. Paralytic poliomyelitis (classic form)

Key feature: Acute asymmetric flaccid paralysis

Clinical Features (Paralytic Form)

  • Motor System (LMN lesion): Sudden flaccid paralysis. Asymmetrical distribution.Muscle hypotonia.Muscle atrophy (later). Fasciculations
  • Reflexes: Hyporeflexia or areflexia
  • Sensory System: Normal sensation (important distinguishing feature)
  • Commonly affected muscles: Proximal > distal. Lower limbs > upper limbs. Respiratory muscles (severe cases)

Bulbar Poliomyelitis

  • Brainstem involvement: Dysphagia. Dysarthria. Respiratory failure. Cranial nerve palsies

CSF Findings: ↑ opening pressure. Clear CSF. ↑ lymphocytes. Mild ↑ protein.Normal glucose

Polioencephalomyelitis

Features

  • Combination of: Flaccid paralysis (spinal cord anterior horn). Brainstem signs. Altered consciousness (if brain involvement)

Differential Diagnosis

1. Guillain-Barré syndrome: Symmetric ascending paralysis. Areflexia. No sensory loss (similar)

  • BUT: no fever, autoimmune, demyelinating

2. Transverse myelitis: Sensory level present. Bilateral motor + sensory loss

3. Stroke: UMN signs. Sudden onset. No fever

4. Myasthenia gravis: Fluctuating weakness. No reflex loss

Prevention: Polio vaccination (OPV/IPV). Hygiene and sanitation

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