What is the primary complication of myasthenia gravis?

Myasthenia gravis is an autoimmune disorder characterized primarily by severe weakness of voluntary muscles. This weakness is caused by a breakdown in the communication between nerves and muscles, resulting in muscle fatigue and decreased muscle strength that can fluctuate throughout the day or with physical activity.

The hallmark of myasthenia gravis is its impact on skeletal muscles, particularly those that control eye movements, facial expression, and swallowing. The most serious complication that can arise from this weakness is a myasthenic crisis, which is a life-threatening condition characterized by respiratory failure due to weakness of the muscles that control breathing.

In contrast, the other options do not accurately reflect the main complications associated with myasthenia gravis. While chronic lung disease may be a concern for someone with respiratory insufficiency related to severe muscle weakness, it is not a direct complication of the disease itself. Acute abdominal pain and thrombosis of blood vessels are not typical issues arising from myasthenia gravis and are unrelated to its pathophysiology or primary symptoms.

Thus, the severe weakness of voluntary muscles is indeed the primary complication of myasthenia gravis, making it the correct choice in this context.