In myasthenia gravis, which statement describes the pattern of weakness with activity?

In myasthenia gravis, which statement describes the pattern of weakness with activity?

• A. They worsen with use and do not change with rest
• B. They worsen with use and improve with rest
• C. They improve with use
• D. They do not change with use

Answer: (B)

Fatigable weakness is the hallmark pattern in myasthenia gravis. Here, muscle strength declines with repeated or sustained use because the autoimmune attack on acetylcholine receptors at the neuromuscular junction reduces the efficiency of signal transmission. With rest, the neuromuscular transmission can temporarily recover, so strength returns for a period. This is why activities cause increasing weakness over time, while a rest period can restore function. Clinically, you often see symptoms like ptosis or diplopia that worsen as the day goes on, reflecting this fatigable pattern.

Fatigable weakness is the hallmark pattern in myasthenia gravis. Here, muscle strength declines with repeated or sustained use because the autoimmune attack on acetylcholine receptors at the neuromuscular junction reduces the efficiency of signal transmission. With rest, the neuromuscular transmission can temporarily recover, so strength returns for a period. This is why activities cause increasing weakness over time, while a rest period can restore function. Clinically, you often see symptoms like ptosis or diplopia that worsen as the day goes on, reflecting this fatigable pattern.