A 61-year-old lady who has been experiencing eyesight issues for the past six months visits the clinic. The patient claims that, particularly in the late afternoon and evening, her eyes quickly feel fatigued. She has smoked a pack of cigarettes every day for the past 35 years, but she doesn't drink or use illegal substances. The extraocular muscles are weak when examined physically. Sensation, deep tendon reflexes, and pupillary reflex are all normal. The exhibit displays a contrast-enhanced CT image of the chest. Which of the following is the most likely mechanism underlying this patient's symptoms?

Question

A 61-year-old lady who has been experiencing eyesight issues for the past six months visits the clinic. The patient claims that, particularly in the late afternoon and evening, her eyes quickly feel fatigued. She has smoked a pack of cigarettes every day for the past 35 years, but she doesn't drink or use illegal substances. The extraocular muscles are weak when examined physically. Sensation, deep tendon reflexes, and pupillary reflex are all normal. The exhibit displays a contrast-enhanced CT image of the chest.   Which of the following is the most likely mechanism underlying this patient's symptoms?

Quizplus · Accepted Answer

Eductional Objective: Circulating antibodies against the acetylcholine receptors at the neuromuscular junction are the cause of myasthenia gravis. Extraocular muscles are often affected, and autoantibody binding results in receptor degradation, which causes variable weakness that becomes worse during the day (eg, ptosis, diplopia). Thymic abnormalities are common among patients (eg, thymoma).

A 61-Year-Old Lady Who Has Been Experiencing Eyesight Issues for the Past