A 4-year-old child presents with cervical lymphadenopathy, grayish-white membrane in the oropharynx extending to the uvula, and hoarseness. The child is not vaccinated. A bull-neck appearance is noted. Which of the following complications occurs by direct spread (not via toxin) in diphtheria?
- A Airway obstruction by membrane extension to the larynx and trachea ✓
- B Myocarditis
- C Peripheral polyneuropathy
- D Palatal palsy
Explanation
In diphtheria, airway obstruction occurs by direct physical extension of the pseudomembrane from the tonsillo-pharyngeal region into the larynx and trachea (mechanical), not via toxin. In contrast, myocarditis, palatal palsy (nasal regurgitation, nasal voice appearing early), peripheral polyneuropathy, and oculomotor palsy are all toxin-mediated effects (diphtheria toxin inhibits protein synthesis via ADP ribosylation of EF-2). Recognition of this distinction is clinically important: the risk of airway obstruction is proportional to the extent of local membrane, while systemic toxicity correlates with toxin absorption.
Reference: Ghai Essential Pediatrics, 10th ed.
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