USMLE® Step 1 style questions USMLE
USMLE® Step 2 style questions USMLE
A 72-year-old man comes to the office because of intermittent fatigue and weakness, especially in the evenings. He says that his head sometimes feels too heavy for his neck, and it is even difficult for him to smile. Physical examination shows a drooping left eyelid that improves with administration of edrophonium. Which of the following is the most likely underlying mechanism of this patient's condition?