A 48-year-old woman receives cosmetic botulinum toxin injections. Five days later, she develops diplopia, ptosis, dysphagia, and descending flaccid paralysis. Vital signs: BP 128/82 mmHg, HR 92 bpm, RR 18/min, temp 37.2°C, SpO2 98%. Electromyography shows brief, small, abundant motor action potentials. She denies recent antibiotic use. Which of the following best describes the toxin's mechanism of action?
- A)Inactivation of the 60S ribosomal subunit
- B)ADP ribosylation of elongation factor 2
- C)Prevention of release of glycine and gamma aminobutyric acid from inhibitory interneurons
- D)Cleavage of SNARE proteins with inhibition of acetylcholine releaseGABARITO
- E)Activation of guanylate cyclase in intestinal epithelium
Explicação
Botulinum toxin is a protease that cleaves SNARE proteins, preventing vesicular release of acetylcholine at the neuromuscular junction. The result is a symmetric descending flaccid paralysis with prominent cranial nerve involvement. Ver explicação completa e trilha adaptativa →