Which disease is a neuromuscular condition with fatigue and weakness that can progress to muscular and respiratory paralysis, featuring double vision and ptosis?

• A. Pernicious anemia
• B. Hay fever
• C. Myasthenia gravis
• D. Autoimmune hemolytic anemia

Answer: (C)

Fatigable weakness caused by impaired transmission at the neuromuscular junction is the key idea. Myasthenia gravis is an autoimmune condition in which antibodies attack postsynaptic acetylcholine receptors at the neuromuscular junction, reducing the muscle’s response to acetylcholine. Because signaling deteriorates with use, strength worsens with activity and improves with rest. The eyes are commonly affected, leading to diplopia (double vision) and ptosis (drooping eyelids); as weakness progresses, bulbar muscles for speech and swallowing and even respiratory muscles can fail, potentially causing respiratory paralysis. The other conditions don’t fit this pattern: pernicious anemia involves B12 deficiency with neuropathy and anemia, hay fever is an allergic condition, and autoimmune hemolytic anemia involves destruction of red blood cells. The combination of fluctuating fatigue with ocular involvement points to myasthenia gravis.