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Emergency Medicine4 papers

Intermediate syndrome

Last edited: 4/10/2026

Overview

Intermediate syndrome (IMS) is a delayed neuromuscular complication of organophosphate (OP) poisoning. It typically occurs 24 to 96 hours after exposure and is characterized by cranial nerve palsies and proximal muscle weakness.

Diagnosis

  • Diagnosis is primarily clinical, based on the temporal relationship between OP exposure and the onset of neuromuscular dysfunction.
  • Key features include weakness of proximal muscles and cranial nerves, with diminished deep tendon reflexes.
  • Electromyography (EMG) may show a characteristic pattern of prolonged repetitive nerve stimulation.

    • Management

  • Adjunctive Therapies:
    • * Pralidoxime use is questioned due to a potential association with increased mortality and longer length of stay compared to atropine alone 1. * Hemopurification combined with atropine significantly reduced mortality and length of stay 1. * N-acetylcysteine (NAC) showed a trend towards reduced length of stay, though not statistically significant 1. * Farinha-Ferreira-Pinto (FFP) did not show significant differences in mortality, length of stay, or ventilatory parameters when used with atropine 1.

    Key Recommendations

  • The routine use of pralidoxime in organophosphate poisoning may be associated with increased adverse outcomes 1. (Evidence: Moderate)
  • Hemopurification combined with atropine significantly reduced mortality and length of stay in organophosphate poisoning 1. (Evidence: Moderate)
  • N-acetylcysteine (NAC) may offer a trend towards reduced length of stay in organophosphate poisoning, although this was not statistically significant 1. (Evidence: Weak)

    • References

    1 Wang L, Wang X. Emergency adjunctive therapy for organophosphate poisoning: A meta-analysis. International emergency nursing 2025. link

    Original source

    1. [1]
      Emergency adjunctive therapy for organophosphate poisoning: A meta-analysis. — Wang L, Wang X International emergency nursing (2025)
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