A 42-year-old woman presents with progressive fatigable ptosis and nasal speech. Vital signs show BP 128/82, HR 88, RR 16, Temp 37.2°C, SpO2 98% on room air. Serum anti-acetylcholine receptor antibodies are positive. Repetitive nerve stimulation demonstrates progressively decreasing compound muscle action potentials with 15% decrement. She denies diplopia. She takes no immunosuppressive medications. Which of the following best explains her neuromuscular disorder?
- A)Presynaptic P Q type voltage gated calcium channel antibodies
- B)Amyotrophic lateral sclerosis
- C)Postsynaptic nicotinic acetylcholine receptor antibodiesGABARITO
- D)Incremental response with repeated stimulation
- E)Botulism
Explicação
Myasthenia gravis is caused by autoantibodies against postsynaptic nicotinic acetylcholine receptors, which reduce end plate potentials and produce a decremental response on repetitive stimulation. Weakness worsens with repeated use because the safety margin o... Ver explicação completa e trilha adaptativa →