A 48-year-old woman presents with a 6-month history of intermittent cranial nerve palsy that has become progressively worse in the past 2 weeks. On examination, ptosis and diplopia are evident. Her condition shows a favorable response to the anticholinesterase inhibitory drug prostigmin (neostigmine). What is the most likely diagnosis?
High-Yield Explanation
Females are affected by myasthenia gravis twice as commonly as males. It is an autoimmune disease that produces antibodies to acetylcholine receptors. The external ocular and other cranial muscles are often involved at an early stage. There is a deficiency in acetylcholine receptors, and thymectomy is often helpful.